Ultrasonic sensor and sweeping robot

Abstract

The invention relates to the technical field of sensors, and discloses an ultrasonic sensor and a sweeping robot, and the ultrasonic sensor comprises a matching layer which is provided with a mounting groove at one end; the piezoelectric element is mounted on the bottom wall of the mounting groove; the backing layer is mounted in the mounting groove; the outer shell is arranged on the peripheral side of the matching layer, and the matching layer and the outer shell are spaced to form a containing gap; the vibration reduction ring can elastically deform in the radial direction of the vibration reduction ring, the vibration reduction ring is arranged on the peripheral side of the matching layer in a sleeving mode and located in the containing gap, and the vibration reduction ring located in the containing gap elastically recovers towards the inner side so as to apply acting force towards the inner side to the piezoelectric element and the backing layer. Therefore, when the ultrasonic sensor uses a single backing layer, the expanded vibration reduction ring is mounted on the peripheral side of the matching layer, so that the vibration reduction ring can effectively weaken residual vibration while having a relatively small wall thickness size, and the performance of the ultrasonic sensor can be maintained while the size of the ultrasonic sensor is reduced.

Description

Technical Field

[0001] This application relates to the field of sensor technology, and in particular to an ultrasonic sensor and a sweeping robot having the ultrasonic sensor. Background Technology

[0002] In related technologies, Chinese patent application CN113390969A discloses an ultrasonic sensor. This ultrasonic sensor includes a housing with a mounting hole, a matching layer embedded in the inner wall of the mounting hole, a piezoelectric ceramic sheet mounted on the matching layer, and a double-layer damping layer. The double-layer damping layer includes a first damping layer and a second damping layer. The first damping layer separates the second damping layer from the piezoelectric ceramic sheet, preventing excessive loss of beneficial vibrations from the ultrasonic sensor. This effectively reduces residual vibrations without suppressing the vibration of the piezoelectric ceramic sheet. The first damping layer is made of silicone rubber, and the second damping layer is made of epoxy resin.

[0003] However, when two damping layers are incorporated into the ultrasonic sensor, the sensor becomes quite large. Given the current miniaturization requirements of household appliances like robotic vacuum cleaners, the installation space for ultrasonic sensors within these appliances is gradually decreasing. If the sensor's size needs to be reduced further, only one damping layer can be installed within the limited space. If the first damping layer is retained, its vibration suppression effect is weak. Although the ultrasonic sensor can maintain good sensitivity, its residual vibration is too large. If the second damping layer is retained, it strongly suppresses both the residual vibration and the normal vibration of the piezoelectric ceramic plate, leading to a significant decrease in the sensor's sensitivity. Therefore, both of these approaches negatively impact the performance of the ultrasonic sensor after its size is reduced. Summary of the Invention

[0004] The purpose of this application is to improve the product quality of ultrasonic sensors by reducing their size while maintaining their performance.

[0005] To achieve the above objectives, this application provides an ultrasonic sensor.

[0006] This application further discloses a robotic vacuum cleaner.

[0007] The ultrasonic sensor according to this application includes: a matching layer, wherein a mounting groove is provided on one end wall of the matching layer along the axial direction of the ultrasonic sensor; a piezoelectric element, wherein the piezoelectric element is mounted on the bottom wall of the mounting groove; a backing layer, wherein the backing layer is mounted in the mounting groove and stacked with the piezoelectric element along the axial direction of the ultrasonic sensor; a housing, wherein the housing is disposed on the outer periphery of the matching layer, and an annular receiving gap is formed between the outer periphery of the matching layer and the inner periphery of the housing; and a damping ring, wherein the damping ring is capable of elastic deformation along its radial direction, and is sleeved on the outer periphery of the matching layer and located within the receiving gap, and the damping ring located within the receiving gap elastically recovers inward to apply an inward force to the piezoelectric element and the backing layer, and wherein the inner diameter of the damping ring in a first initial state is D0, and the inner diameter of the damping ring in a first deformed state is D1, wherein D0 and D1 satisfy the relationship: 0.1≤(D1-D0) / D0≤0.2.

[0008] According to the ultrasonic sensor of this application, when the ultrasonic sensor uses a single backing layer, by installing a stretched damping ring on the outer periphery of the matching layer, the damping ring can effectively reduce residual vibration while having a smaller wall thickness. This allows the ultrasonic sensor to maintain its performance while reducing its size, thereby improving the product quality of the ultrasonic sensor.

[0009] In some examples of this application, the outer peripheral wall of the damping ring is provided with at least one protruding damping rib, which is in a stop-fitting engagement with the inner peripheral wall of the housing. In the axial direction of the ultrasonic sensor, the damping rib is located between the end wall of the matching layer away from the mounting groove and the end wall of the piezoelectric element away from the bottom wall of the mounting groove.

[0010] In some examples of this application, the outer peripheral wall of the damping ring is provided with a plurality of damping ribs, the plurality of damping ribs are arranged sequentially along the axial direction of the ultrasonic sensor, and the plurality of damping ribs are symmetrically arranged on both sides of the center line of the damping ring along the axial direction of the ultrasonic sensor.

[0011] In some examples of this application, the outer diameter of the damping ring in the first deformation state is smaller than the inner diameter of the outer shell, and the outer diameter of the damping rib in the second initial state is larger than the inner diameter of the outer shell, so that the damping rib is in a second deformation state of being compressed radially when installed in the receiving gap. The thickness of the damping rib in the second initial state is H0, and the thickness of the damping rib in the second deformation state is H1. H0 and H1 satisfy the relationship: 0.1≤(H0-H1) / H0≤0.35.

[0012] In some examples of this application, the piezoelectric element includes a piezoelectric ceramic component, a first electrode, and a second electrode. In the axial direction of the ultrasonic sensor, the piezoelectric ceramic component has a first sidewall and a second sidewall facing away from each other. The first sidewall is disposed opposite to the bottom wall of the mounting groove. The first electrode is disposed on the first sidewall, and the second electrode is disposed on the second sidewall. The second sidewall is also provided with a first connecting portion and a second connecting portion. The first connecting portion is electrically connected to the first electrode, and the second connecting portion is electrically connected to the second electrode.

[0013] In some examples of this application, the first electrode extends radially from the center of the first sidewall toward the edge of the first sidewall along the ultrasonic sensor, and / or a portion of the structure of the first electrode is disposed on the outer peripheral wall of the piezoelectric ceramic element.

[0014] In some examples of this application, the area of ​​the first electrode is S1 and the area of ​​the first sidewall is S2, satisfying the relationship: 0.9≤S1 / S2≤1.1.

[0015] In some examples of this application, a connecting electrode is connected between the first electrode and the first connecting portion, and the connecting electrode is at least partially disposed on the outer peripheral wall of the piezoelectric ceramic component; the first connecting portion is disposed on the edge of the first side wall, and on the second side wall, the first connecting portion and the second connecting portion are spaced apart along the circumference of the ultrasonic sensor, and the first connecting portion and the second electrode are spaced apart, so that the projection of the second electrode is located within the projection of the first electrode in the axial direction of the ultrasonic sensor.

[0016] In some examples of this application, the outer peripheral wall of the piezoelectric ceramic part is mated with the inner peripheral wall of the mounting groove, the outer diameter of the matching layer is D2, the outer diameter of the piezoelectric ceramic part is D3, and D2 and D3 satisfy the relationship: 1.15≤D2 / D3≤1.45.

[0017] The robotic vacuum cleaner according to this application includes the aforementioned ultrasonic sensor.

[0018] According to the sweeping robot of this application, the sweeping robot is equipped with an ultrasonic sensor. When the ultrasonic sensor uses a single backing layer, by installing a stretched damping ring on the outer periphery of the matching layer, the damping ring can effectively reduce residual vibration while having a smaller wall thickness. This can reduce the size of the ultrasonic sensor while maintaining its performance, thereby improving the product quality of the ultrasonic sensor and meeting the sweeping robot's requirement to identify the material of the surface to be cleaned. At the same time, it can meet the miniaturization design requirements of the sweeping robot. Attached Figure Description

[0019] Figure 1 This is a cross-sectional view of the ultrasonic sensor according to an embodiment of this application; Figure 2 This is a partial cross-sectional view of the ultrasonic sensor when the damping ring of this application is in the open state; Figure 3 This is a cross-sectional view of the vibration damping ring and vibration damping rib in the initial state according to an embodiment of this application; Figure 4 This is a front view of a piezoelectric element according to an embodiment of this application; Figure 5 This is a rear view of a piezoelectric element according to an embodiment of this application; Figure 6 This is a side view of a piezoelectric element according to an embodiment of this application; Figure 7 This is a graph showing the relationship between the residual vibration time of the ultrasonic sensor in an embodiment of this application and the Shore hardness of the damping ring. Figure 8 This is a graph showing the relationship between the residual vibration time of the ultrasonic sensor in an embodiment of this application and the radial tensile rate of the damping ring. Figure 9 This is a graph showing the relationship between the sensitivity of the ultrasonic sensor in this embodiment of the application and the ratio of the outer diameter D2 of the matching layer to the outer diameter D3 of the piezoelectric ceramic part.

[0020] In the diagram, 100 represents an ultrasonic sensor. 1. Matching layer; 11. Mounting slot; 2. Piezoelectric element; 21. Piezoelectric ceramic component; 211. First sidewall; 212. Second sidewall; 22. First electrode; 23. Second electrode; 24. First connecting part; 25. Second connecting part; 26. Connecting electrode; 3. Backing layer; 4. Outer shell; 41. Accommodation gap; 5. Vibration damping ring; 51. Vibration damping rib; 6. Controller; 7. Enclosure; 8. Wire. Detailed Implementation

[0021] The specific embodiments of this application will be described in further detail below with reference to the accompanying drawings and examples. The following examples are used to illustrate this application, but are not intended to limit the scope of this application.

[0022] like Figures 1-9As shown in the illustration, this application discloses an ultrasonic sensor 100. This ultrasonic sensor 100 is applicable to various household appliances. For example, by installing the ultrasonic sensor 100 inside a robotic vacuum cleaner, the robotic vacuum cleaner can identify the material of the surface to be cleaned, thereby enabling it to select an appropriate working mode based on the material. Of course, the ultrasonic sensor 100 of this application is also applicable to other devices, such as industrial robots and vehicles.

[0023] Furthermore, compared to most ultrasonic sensors 100 on the market, the ultrasonic sensor 100 of this application embodiment has a smaller structural size, so that the ultrasonic sensor 100 can be installed in a smaller installation space. For example, in some specific embodiments, the outer diameter of the ultrasonic sensor 100 is 12mm and the axial dimension of the ultrasonic sensor 100 is 9mm.

[0024] like Figures 1-9 As shown, the ultrasonic sensor 100 according to an embodiment of this application includes: a matching layer 1, a piezoelectric element 2, a backing layer 3, a housing 4, and a damping ring 5. In the axial direction of the ultrasonic sensor 100, one end wall of the matching layer 1 is provided with a mounting groove 11, allowing the axial direction of the ultrasonic sensor 100 to be directed... Figure 1 The mounting groove 11 extends along the axial direction of the ultrasonic sensor 100 in the vertical direction.

[0025] The piezoelectric element 2 is installed on the bottom wall of the mounting groove 11. The piezoelectric element 2 is used to transmit and receive vibrations. Specifically, after the piezoelectric element 2 is electrically connected to the power supply, the piezoelectric element 2 vibrates under the action of the current and generates ultrasonic waves. The ultrasonic waves can be transmitted to the outside of the ultrasonic sensor 100 through the matching layer 1 in the forward transmission direction. The forward transmission direction can refer to the direction from the piezoelectric element 2 toward the end of the matching layer 1 away from the mounting groove 11. Then the ultrasonic waves are transmitted along the air to the surface to be tested. When the ultrasonic sensor 100 is installed in the robot vacuum cleaner, the surface to be tested can be the surface to be cleaned as described above. The surface to be tested can reflect the ultrasonic waves back to the ultrasonic sensor 100. The ultrasonic waves reflected to the ultrasonic sensor 100 are transmitted along the matching layer 1 to the piezoelectric element 2, so that the piezoelectric element 2 generates a corresponding current signal according to the frequency of the ultrasonic waves. In this way, the device can determine the material of the surface to be tested, such as carpet, floor, etc., according to the frequency changes of the transmitted and received ultrasonic waves.

[0026] In some embodiments, the piezoelectric element 2 can be bonded to the bottom wall or inner peripheral wall of the mounting groove using an adhesive, thereby fixing the piezoelectric element 2 at the mounting groove.

[0027] Furthermore, there is only one backing layer 3, which is installed in the mounting groove 11 and is stacked with the piezoelectric element 2 along the axial direction of the ultrasonic sensor 100. The backing layer 3 is used to absorb the vibration transmitted by the piezoelectric element 2 in the reverse transmission direction, which is opposite to the forward transmission direction mentioned above. This can make the ultrasonic sensor 100 emit ultrasonic waves with better directionality, thereby making the ultrasonic sensor 100 more accurate in detection.

[0028] In some embodiments, the backing layer 3 can be a silicone component, which is easily formed by potting or injection molding, thus reducing the processing difficulty of the ultrasonic sensor 100. When the matching layer 1, the piezoelectric element 2, and the backing layer 3 are assembled together, an integrated ultrasonic transmitting and receiving unit can be formed. That is, the matching layer 1 not only transmits vibrations but also serves as a mounting bracket for the piezoelectric element 2 and the backing layer 3.

[0029] In some embodiments, the backing layer 3 can also be formed by direct potting compound. When the backing layer 3 is formed by potting compound, the backing layer 3 can be used to absorb the vibration of the piezoelectric element 2 and can also be used to fix the piezoelectric element 2, so that the piezoelectric element 2 and the mounting groove do not need to be bonded with adhesive, further saving materials.

[0030] like Figure 1 , Figure 2 As shown, the outer casing 4 is located on the outer periphery of the matching layer 1. The outer casing 4 protects the aforementioned ultrasonic transmitting and receiving unit, thereby improving the operational stability of the ultrasonic sensor 100. Furthermore, the outer casing 4 also houses a controller 6, a sealing member 7, and wires 8. The controller 6 is electrically connected to the piezoelectric element 2, and the wires 8 are electrically connected between the controller 6 and an external power source, and between the controller 6 and the piezoelectric element 2. The controller 6 controls the power supply to the piezoelectric element 2 to adjust its operating cycle and frequency. The sealing member 7 seals the interior of the outer casing 4, preventing liquids from seeping into the outer casing 4 and damaging the piezoelectric element 2.

[0031] Furthermore, an annular receiving gap 41 is formed between the outer peripheral wall of the matching layer 1 and the inner peripheral wall of the outer shell 4. The damping ring 5 can elastically deform along its radial direction, and the damping ring 5 is sleeved on the outer peripheral side of the matching layer 1 and located within the receiving gap 41. The matching layer 1 is reliably connected together through the damping ring 5. The damping ring 5 located within the receiving gap 41 elastically recovers inward to apply an inward force to the piezoelectric element 2 and the backing layer 3. That is, the damping ring 5 located within the receiving gap 41 is in a first deformation state of being stretched open by the matching layer 1. The inner diameter of the damping ring 5 in the first initial state is smaller than the outer diameter of the matching layer 1. Thus, when the damping ring 5 and the matching layer 1 are assembled together by an interference fit, by setting the damping ring 5 between the matching layer 1 and the outer shell 4, the damping ring 5 can absorb the vibration transmitted from the matching layer 1 to the outer shell 4, thereby reducing the residual vibration of the ultrasonic sensor 100 and improving the sensitivity of the ultrasonic sensor 100.

[0032] Furthermore, such as Figure 2 , Figure 3 As shown, the inner diameter of the damping ring 5 in the first initial state is D0, the inner diameter of the damping ring 5 in the first deformation state is D1, and the Shore hardness of the damping ring 5 is HA. D0, D1 and HA satisfy the following relationship: 0.1≤(D1-D0) / D0≤0.2, 50 ShoreA≤HA≤80 ShoreA. In the above calculation formula, (D1-D0) / D0 can refer to the radial tensile ratio of the damping ring 5 when it transforms from the first initial state to the first deformation state. According to Hooke's law, after the damping ring 5 is stretched, the magnitude of the radial binding force of the damping ring 5 on the matching layer 1 is positively correlated with the stiffness coefficient of the damping ring 5 and the wall thickness deformation of the damping ring 5. The greater the radial binding force of the damping ring 5, the less likely the damping ring 5 is to vibrate relative to the matching layer 1, and the better the damping ring 5 absorbs residual vibration. Conversely, the smaller the radial binding force of the damping ring 5, the more likely the damping ring 5 is to vibrate relative to the matching layer 1, and the worse the damping ring 5 absorbs residual vibration.

[0033] Therefore, by increasing the stiffness coefficient and wall thickness deformation of the damping ring 5, the performance of the damping ring 5 in absorbing residual vibration can be improved. Specifically, increasing the stiffness coefficient of the damping ring 5 can be achieved by increasing its hardness, such as... Figure 7 As shown, Figure 7 The horizontal axis represents the Shore hardness of the damping ring 5, and the vertical axis represents the duration of residual vibration of the ultrasonic sensor 100. When the Shore hardness HA of the damping ring 5 is less than 50 Shore A, the damping ring 5 has a weak ability to absorb residual vibration and cannot meet the performance requirements of the ultrasonic sensor 100. When the Shore hardness HA of the damping ring 5 is greater than 80 Shore A, the damping ring 5 is too hard and difficult to install onto the outer periphery of the matching layer 1, thus affecting the assembly efficiency of the ultrasonic sensor 100.

[0034] Therefore, by designing the Shore A hardness HA of the damping ring 5 to be 50 Shore A to 80 Shore A, it is easy to install the damping ring 5 on the outer periphery of the matching layer 1, and at the same time, the damping ring 5 can have suitable residual vibration absorption performance.

[0035] Meanwhile, based on the Poisson effect, by radially expanding the damping ring 5, the wall thickness of the damping ring 5 can be reduced. By expanding the damping ring 5 and installing it on the outer periphery of the matching layer 1, when the volume of the ultrasonic sensor 100 decreases and the distance between the outer periphery of the matching layer 1 and the inner periphery of the outer shell 4 decreases, the wall thickness of the damping ring 5 in the first deformation state is even smaller, allowing the damping ring 5 to be smoothly installed within the receiving gap 41, and at this time, the radial binding force of the damping ring 5 is greater. Figure 8 As shown, Figure 8 The horizontal axis represents the radial tensile ratio of the damping ring 5, and the vertical axis represents the duration of residual vibration of the ultrasonic sensor 100. When the radial tensile ratio of the damping ring 5 is less than 0.1, its ability to absorb residual vibration is weak and cannot meet the performance requirements of the ultrasonic sensor 100. When the radial tensile ratio of the damping ring 5 is greater than 0.2, further expanding the damping ring 5 outward does not significantly improve its ability to absorb residual vibration, and the damping ring 5 is easily broken, thus affecting the service life of the ultrasonic sensor 100. Therefore, by designing the radial tensile ratio of the damping ring 5 to be between 0.1 and 0.2, the service life of the damping ring 5 can be extended while ensuring that it has suitable residual vibration absorption performance.

[0036] Therefore, when the ultrasonic sensor 100 uses a single backing layer 3, by installing a stretched damping ring 5 on the outer periphery of the matching layer 1, the damping ring 5 can effectively reduce residual vibration while having a smaller wall thickness. This allows the ultrasonic sensor 100 to maintain its performance while reducing its size, thereby improving the product quality of the ultrasonic sensor 100.

[0037] like Figures 1-3As shown, in some embodiments of this application, the outer peripheral wall of the damping ring 5 is provided with at least one protruding damping rib 51. The damping rib 51 and the damping ring 5 are integrally formed, that is, the damping rib 51 and the damping ring 5 are manufactured by an integral forming process. The damping rib 51 abuts against the inner peripheral wall of the outer shell 4. By providing the damping rib 51 between the damping ring 5 and the inner peripheral wall of the outer shell 4, the friction between the damping rib 51 and the outer shell 4 can ensure that the matching layer 1 is reliably installed in the outer shell 4 through the damping ring 5. Furthermore, the provision of the damping rib 51 can reduce the contact area between the outer shell 4 and the damping ring 5, thereby further increasing the difficulty of vibration transmission between the outer shell 4 and the damping ring 5, and further reducing the residual vibration of the ultrasonic sensor 100.

[0038] And, as Figure 2 As shown, in the axial direction of the ultrasonic sensor 100, the damping rib 51 is located between the end wall of the matching layer 1 away from the mounting groove 11 and the end wall of the piezoelectric element 2 away from the bottom wall of the mounting groove 11. This allows the damping rib 51 to be positioned close to the area of ​​high vibration intensity of the ultrasonic transmitting and receiving unit, thereby improving the damping effect of the damping rib 51 in blocking the connection between the housing 4 and the ultrasonic transmitting and receiving unit. This further reduces the residual vibration of the ultrasonic sensor 100, ensuring good performance of the ultrasonic sensor 100 in a small-sized structure.

[0039] Furthermore, such as Figure 2 , Figure 3 As shown, the outer peripheral wall of the vibration damping ring 5 is provided with multiple vibration damping ribs 51, which are arranged sequentially along the axial direction of the ultrasonic sensor 100. Of course, to reduce the vibration transmission path between the vibration damping ring 5 and the outer casing 4, the number of vibration damping ribs 51 can be minimized, for example, two ribs can be used. Furthermore, the multiple vibration damping ribs 51 are symmetrically arranged on both sides of the centerline of the vibration damping ring 5 along the axial direction of the ultrasonic sensor 100. This arrangement facilitates reducing the directional nature of the vibration damping ring 5 assembly, thereby improving the assembly efficiency of the ultrasonic sensor 100. Simultaneously, this arrangement prevents excessive local vibration on one side of the vibration damping ring 5, thus extending the service life of the vibration damping ring 5.

[0040] like Figures 1-3As shown, in some embodiments of this application, the outer diameter of the damping ring 5 in the first deformed state is smaller than the inner diameter of the outer shell 4, and the outer diameter of the damping rib 51 in the second initial state is larger than the inner diameter of the outer shell 4, so that the damping rib 51 is in a compressed state along its radial direction when installed in the receiving gap 41. By squeezing the damping rib 51, the damping rib 51 undergoes elastic deformation and generates elastic force. The elastic force can press the damping rib 51 against the inner peripheral wall of the outer shell 4, and the friction between the damping rib 51 and the outer shell 4 can reliably fix the ultrasonic transmitting and receiving unit inside the outer shell 4.

[0041] And, as Figure 1 , Figure 3 As shown, the thickness of the damping rib 51 in the second initial state is H0, and the thickness of the damping rib 51 in the second deformed state is H1. H0 and H1 satisfy the relationship: 0.1≤(H0-H1) / H0≤0.35. In the above calculation formula, (H0-H1) / H0 can refer to the radial compression ratio of the damping rib 51 when it transforms from the second initial state to the second deformed state. When the radial compression ratio of the damping rib 51 is less than 0.1, the compression amount of the damping rib 51 within the accommodating gap 41 is too small, resulting in insufficient friction between the damping rib 51 and the outer shell 4. This will worsen the fixing effect between the damping ring 5 and the outer shell 4, making it easy for the damping ring 5 and the outer shell 4 to loosen when the ultrasonic sensor 100 is working, thereby reducing the damping ring 5's suppression effect on residual vibration.

[0042] When the radial compression ratio of the damping rib 51 is greater than 0.35, the compression of the damping rib 51 within the accommodating gap 41 is excessive, causing the damping rib 51 to be under strong pressure for a long time. This increases the assembly difficulty of the ultrasonic sensor 100 and makes the damping rib 51 prone to fatigue damage. Simultaneously, excessive rigidity of the damping rib 51 will excessively suppress the normal vibration of the piezoelectric element 2, thereby reducing the sensitivity of the ultrasonic sensor 100 and affecting its performance. Therefore, by designing the radial compression ratio of the damping rib 51 to be between 0.1 and 0.35, while ensuring that the damping ring 5 reliably fixes the ultrasonic transmitting and receiving unit within the housing 4, the damping rib 51 can also possess suitable residual vibration suppression performance.

[0043] like Figure 4 , Figure 6As shown, in some embodiments of this application, the piezoelectric element 2 includes a piezoelectric ceramic component 21, a first electrode 22, and a second electrode 23. Both the first electrode 22 and the second electrode 23 are adapted to be electrically connected to a power source. When the power source supplies power to the first electrode 22 and the second electrode 23, the piezoelectric ceramic component 21 vibrates at a high frequency under the action of the electric field between the first electrode 22 and the second electrode 23. In the axial direction of the ultrasonic sensor 100, the piezoelectric ceramic component 21 has a first sidewall 211 and a second sidewall 212 facing away from each other. The first sidewall 211 is disposed opposite to the bottom wall of the mounting groove 11. The first electrode 22 is disposed on the first sidewall 211, and the second electrode 23 is disposed on the second sidewall 212. The second sidewall 212 is also provided with a first connecting portion 24 and a second connecting portion 25. The first connecting portion 24 is electrically connected to the first electrode 22, and the second connecting portion 25 is electrically connected to the second electrode 23.

[0044] In some specific implementation plans, such as Figure 4 As shown, the first connecting part 24 can be constructed as an independent structure, while the second connecting part 25 and the second electrode 23 are constructed as an integral structure. By setting both the first connecting part 24 and the second connecting part 25 on the second sidewall 212, the area on the first sidewall 211 for mounting the first electrode 22 is larger, thereby enabling the piezoelectric ceramic component 21 to form a larger effective vibration area when vibrating. This increases the piezoelectric conversion area of ​​the piezoelectric element 2 and improves the signal amplitude output by the piezoelectric element 2. When the volume of the ultrasonic sensor 100 is reduced and the structural size of the piezoelectric element 2 is reduced, the ultrasonic sensor 100 can maintain high sensitivity to meet the detection requirements of the equipment.

[0045] Furthermore, such as Figure 6 As shown, the first electrode 22 extends from the center of the first sidewall 211 radially toward the edge of the first sidewall 211 of the ultrasonic sensor 100, and / or, a portion of the structure of the first electrode 22 is disposed on the outer peripheral wall of the piezoelectric ceramic component 21. By extending the first electrode 22 from the center of the first sidewall 211 radially toward the edge of the first sidewall 211 of the ultrasonic sensor 100, the first electrode 22 can fully utilize the surface of the first sidewall 211, thereby increasing the area of ​​the first electrode 22.

[0046] By placing a portion of the structure of the first electrode 22 on the outer peripheral wall of the piezoelectric ceramic component 21, the portion of the first electrode 22 on the outer peripheral wall of the piezoelectric ceramic component 21 and the portion of the first sidewall 211 are connected at the edge where the outer peripheral wall of the piezoelectric ceramic component 21 intersects with the first sidewall 211. Since the first electrode 22 has fully utilized the surface of the first sidewall 211, the area of ​​the first electrode 22 can be further increased, thereby further expanding the area of ​​the piezoelectric ceramic component 21 that participates in effective vibration. This is beneficial for improving the charge conversion capability of the ultrasonic sensor 100, and further improves the output signal amplitude of the ultrasonic sensor 100, thus enhancing the sensitivity of the ultrasonic sensor 100.

[0047] Furthermore, the area of ​​the first electrode 22 is S1, and the area of ​​the first sidewall 211 is S2, satisfying the relationship: 0.9 ≤ S1 / S2 ≤ 1.1. Wherein, when the ratio of the area S1 of the first electrode 22 to the area S2 of the first sidewall 211 is 0.9 to 1.1, it can be essentially equivalent to the ratio of the diameter of the first electrode 22 to the diameter of the first sidewall 211 being 0.95 to 1.05 when both the first electrode 22 and the first sidewall 211 are circular.

[0048] It should be noted that when the ratio of the area S1 of the first electrode 22 to the area S2 of the first sidewall 211 is 0.9 to 1.0, the first electrode 22 is completely formed on the first sidewall 211. When the ratio of the area S1 of the first electrode 22 to the area S2 of the first sidewall 211 is 1.0 to 1.1, the first electrode 22 occupies part of the outer peripheral wall surface of the piezoelectric ceramic part 21 while completely occupying the surface of the first sidewall 211.

[0049] When the ratio of the area S1 of the first electrode 22 to the area S2 of the first sidewall 211 is less than 0.9, and the volume of both the ultrasonic sensor 100 and the piezoelectric element 2 has been reduced, the area S1 of the first electrode 22 is too small, and the effective vibration area that the first electrode 22 can cover on the first sidewall 211 is too small. This results in the ultrasonic sensor 100 outputting too low a charge, the ultrasonic sensor 100 having too small a signal amplitude, and the ultrasonic sensor 100's sensitivity not meeting the equipment's usage requirements, which is detrimental to the ultrasonic detection distance and echo recognition stability.

[0050] When the ratio of the area S1 of the first electrode 22 to the area S2 of the first sidewall 211 is greater than 1.1, the surface area occupied by the first electrode 22 on the outer peripheral wall of the piezoelectric ceramic part 21 is too large, which increases the probability of the electric field between the first electrode 22 and the second electrode 23 being broken down, reduces the working stability of the ultrasonic sensor 100, and affects the service life of the ultrasonic sensor 100.

[0051] Therefore, by designing the ratio of the area S1 of the first electrode 22 to the area S2 of the first sidewall 211 to be 0.9 to 1.1, while maximizing the effective vibration area of ​​the first sidewall 211 covered by the first electrode 22, the electric field between the first electrode 22 and the second electrode 23 can be prevented from being broken down. This ensures that the sensitivity of the ultrasonic sensor 100 meets the requirements of the device, while also improving the working stability of the ultrasonic sensor 100.

[0052] like Figure 5 As shown, in some embodiments of this application, a connecting electrode 26 is connected between the first electrode 22 and the first connecting portion 24. The connecting electrode 26 can realize the electrical connection between the first electrode 22 and the first connecting portion 24. Compared with setting the wire 8 between the first electrode 22 and the first connecting portion 24, using the connecting electrode 26 instead of the wire can reduce the space occupied by the wire on the outer periphery of the piezoelectric element 2. The connecting electrode 26 is at least partially disposed on the outer peripheral wall of the piezoelectric ceramic part 21. This can make the lead-out path of the connecting electrode 26 more reasonably distributed in the circumferential direction of the piezoelectric ceramic part 21, which is beneficial to reduce the interference of the connecting electrode 26 on the vibration surface of the piezoelectric ceramic part 21.

[0053] Furthermore, the first connecting portion 24 is disposed at the edge of the first sidewall 211, and on the second sidewall 212, the first connecting portion 24 and the second connecting portion 25 are spaced apart along the circumference of the ultrasonic sensor 100. This prevents short circuits between the first connecting portion 24 and the second connecting portion 25. The first connecting portion 24 is also spaced apart from the second electrode 23, so that the projection of the second electrode 23 lies within the projection of the first electrode 22 along the axial direction of the ultrasonic sensor 100. In other words, the area of ​​the second electrode 23 is smaller than the area of ​​the first electrode 22. This further prevents the electric field between the first electrode 22 and the second electrode 23 from being broken down, thereby ensuring that the sensitivity of the ultrasonic sensor 100 meets the requirements of the device while improving the operational stability of the ultrasonic sensor 100.

[0054] like Figure 1 , Figure 6 As shown, in some embodiments of this application, the outer peripheral wall of the piezoelectric ceramic component 21 abuts against the inner peripheral wall of the mounting groove 11. This allows the piezoelectric ceramic component 21 to occupy as much space as possible in the matching layer 1 along its radial direction, thereby effectively increasing the effective vibration area of ​​the piezoelectric ceramic component 21. Let the outer diameter of the matching layer 1 be D2, and the outer diameter of the piezoelectric ceramic component 21 be D3. D2 and D3 satisfy the relationship: 1.15≤D2 / D3≤1.45. It should be noted that when the outer peripheral wall of the matching layer 1 fits well with the inner peripheral wall of the damping ring 5, the outer diameter D2 of the matching layer 1 is equal to the inner diameter D1 of the damping ring 5 in the first deformation state.

[0055] like Figure 9As shown, the ratio of the outer diameter D2 of the matching layer 1 to the outer diameter D3 of the piezoelectric ceramic component 21 was measured and the corresponding sensitivity of the ultrasonic sensor 100 was plotted. Figure 9 , Figure 9 The horizontal axis represents the ratio of the outer diameter D2 of the matching layer 1 to the outer diameter D3 of the piezoelectric ceramic component 21, and the vertical axis represents the sensitivity of the ultrasonic sensor 100. Based on the curves in the figure, it can be seen that the preferred value for the ratio of the outer diameter D2 of the matching layer 1 to the outer diameter D3 of the piezoelectric ceramic component 21 is 1.25. When the ratio of the outer diameter D2 of the matching layer 1 to the outer diameter D3 of the piezoelectric ceramic component 21 is less than 1.15 or greater than 1.45, the sensitivity of the ultrasonic sensor 100 is difficult to meet the usage requirements of most devices on the market.

[0056] According to some specific embodiments of this application, the resonant frequency Fr of the piezoelectric element 2 is less than 300kHz, and the anti-resonant frequency Fp of the piezoelectric element 2 is greater than 300kHz, to ensure that the piezoelectric element 2 achieves maximum transmission and reception sensitivity in actual operation. Furthermore, the outer diameter D3 of the piezoelectric ceramic component 21 can be designed to be 7.0mm to 7.5mm. To avoid short-circuiting between the first electrode 22 and the second electrode 23 in the axial direction of the ultrasonic sensor 100, the thickness t of the piezoelectric ceramic component 21 can be designed to be not less than 0.6mm. It should be noted that if the thickness of the piezoelectric ceramic component 21 is too large, it will not only affect the resonant frequency Fr and its vibration mode of the piezoelectric element 2, but also increase the overall axial dimension of the ultrasonic sensor 100, thus failing to meet the dimensional design requirements of the ultrasonic sensor 100.

[0057] The ultrasonic sensor 100 manufactured according to the above embodiments of this application has an outer diameter of 12 mm and an axial dimension of 9 mm. Compared with commercially available ultrasonic sensors with an outer diameter of 16 mm and an axial dimension of 12 mm, the ultrasonic sensor 100 of this application has a residual vibration time of 272 μs and a sensitivity of 1.6 Vpp, while the aforementioned commercially available ultrasonic sensors have a residual vibration time of 268 μs and a sensitivity of 1.76 Vpp. Therefore, the ultrasonic sensor 100 of this application has a smaller structural size than commercially available ultrasonic sensors, while also having good sensitivity and residual vibration time, which can meet the usage requirements of most devices.

[0058] Based on this, this application further discloses a robotic vacuum cleaner, which, according to an embodiment of this application, includes the ultrasonic sensor 100 described above. When the ultrasonic sensor 100 uses a single backing layer 3, by installing a stretched damping ring 5 on the outer periphery of the matching layer 1, the damping ring 5 can effectively reduce residual vibration while having a smaller wall thickness. This allows for a reduction in the volume of the ultrasonic sensor 100 while maintaining its performance, thereby improving the product quality of the ultrasonic sensor 100. This meets the requirements of the robotic vacuum cleaner to identify the material of the surface to be cleaned, and also meets the miniaturization design requirements of the robotic vacuum cleaner.

[0059] The above description is only a preferred embodiment of this application. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of this application, and these improvements and substitutions should also be considered within the scope of protection of this application.

Claims

1. An ultrasonic sensor, characterized in that, include: A matching layer is provided with a mounting groove on one end wall along the axial direction of the ultrasonic sensor. A piezoelectric element, wherein the piezoelectric element is mounted on the bottom wall of the mounting groove; A backing layer, which is installed in the mounting groove and stacked with the piezoelectric element along the axial direction of the ultrasonic sensor; The outer shell is disposed on the outer periphery of the matching layer, and the outer peripheral wall of the matching layer and the inner peripheral wall of the outer shell are spaced apart to form an annular receiving gap; A vibration damping ring is provided, which is capable of elastic deformation along its radial direction and is fitted on the outer periphery of the matching layer and located within the receiving gap. The vibration damping ring located within the receiving gap elastically recovers inward to apply an inward force to the piezoelectric element and the backing layer. The inner diameter of the vibration damping ring in the first initial state is D0, and the inner diameter of the vibration damping ring in the first deformed state is D1. D0 and D1 satisfy the relationship: 0.1≤(D1-D0) / D0≤0.

2.

2. The ultrasonic sensor according to claim 1, characterized in that, The outer peripheral wall of the damping ring is provided with at least one protruding damping rib. The damping rib is in a stop-fitting engagement with the inner peripheral wall of the outer shell. In the axial direction of the ultrasonic sensor, the damping rib is located between the end wall of the matching layer away from the mounting groove and the end wall of the piezoelectric element away from the bottom wall of the mounting groove.

3. The ultrasonic sensor according to claim 2, characterized in that, The outer peripheral wall of the vibration damping ring is provided with a plurality of vibration damping ribs, which are arranged sequentially along the axial direction of the ultrasonic sensor, and are symmetrically arranged on both sides of the center line of the vibration damping ring along the axial direction of the ultrasonic sensor.

4. The ultrasonic sensor according to claim 2, characterized in that, The outer diameter of the damping ring in the first deformation state is smaller than the inner diameter of the outer shell, and the outer diameter of the damping rib in the second initial state is larger than the inner diameter of the outer shell, so that the damping rib is in a second deformation state of being compressed radially when installed in the receiving gap. The thickness of the damping rib in the second initial state is H0, and the thickness of the damping rib in the second deformation state is H1. H0 and H1 satisfy the relationship: 0.1≤(H0-H1) / H0≤0.

35.

5. The ultrasonic sensor according to claim 1, characterized in that, The piezoelectric element includes a piezoelectric ceramic component, a first electrode, and a second electrode. In the axial direction of the ultrasonic sensor, the piezoelectric ceramic component has a first sidewall and a second sidewall facing away from each other. The first sidewall is disposed opposite to the bottom wall of the mounting groove. The first electrode is disposed on the first sidewall, and the second electrode is disposed on the second sidewall. The second sidewall is also provided with a first connecting part and a second connecting part, wherein the first connecting part is electrically connected to the first electrode and the second connecting part is electrically connected to the second electrode.

6. The ultrasonic sensor according to claim 5, characterized in that, The first electrode extends radially from the center of the first sidewall toward the edge of the ultrasonic sensor, and / or, A portion of the structure of the first electrode is disposed on the outer peripheral wall of the piezoelectric ceramic component.

7. The ultrasonic sensor according to claim 6, characterized in that, The area of ​​the first electrode is S1, and the area of ​​the first sidewall is S2, satisfying the relationship: 0.9≤S1 / S2≤1.

1.

8. The ultrasonic sensor according to claim 5, characterized in that, A connecting electrode is connected between the first electrode and the first connecting portion, and at least a portion of the connecting electrode is disposed on the outer peripheral wall of the piezoelectric ceramic component. The first connecting portion is disposed on the edge of the first sidewall. On the second sidewall, the first connecting portion and the second connecting portion are spaced apart along the circumference of the ultrasonic sensor, and the first connecting portion is spaced apart from the second electrode, so that the projection of the second electrode is located within the projection of the first electrode in the axial direction of the ultrasonic sensor.

9. The ultrasonic sensor according to claim 5, characterized in that, The outer peripheral wall of the piezoelectric ceramic component is mated to the inner peripheral wall of the mounting groove. The outer diameter of the matching layer is D2, and the outer diameter of the piezoelectric ceramic component is D3. D2 and D3 satisfy the relationship: 1.15≤D2 / D3≤1.

45.

10. A robotic vacuum cleaner, characterized in that, Includes an ultrasonic sensor according to any one of claims 1-9.

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