Ultrasonic sensor housing and ultrasonic sensor thereof

Abstract

An ultrasonic sensor housing and ultrasonic sensor thereof. The ultrasonic sensor housing has a cavity opening at the front end of the housing. The cavity has a rectangular cross-section and is enclosed by a bottom wall, two opposing long sidewalls, and two opposing short sidewalls. The two long sidewalls are symmetrically provided with two first recesses, each symmetrically located on either side of the centerline of the short side of the cavity. Each first recess extends along the depth of the cavity, and the edge of each first recess is circular or elliptical. The present invention improves the sensor's sound pressure while ensuring a large ratio between the horizontal and vertical detection angles, and is easy to manufacture.

Description

Technical Field

[0001] The present invention relates to ultrasonic sensor technology. Background Art

[0002] An ultrasonic sensor consists of a metal housing and a piezoelectric component. The housing has an open cavity at one end, and the piezoelectric component is located within the cavity. When current flows through the piezoelectric component, it converts electrical energy into mechanical energy, causing the metal housing's base plate (also known as the diaphragm) to deform and emit ultrasonic waves. When the ultrasonic waves encounter an obstacle, they are reflected back to the ultrasonic sensor. The time difference between ultrasonic reception and transmission can be used to determine physical information such as the obstacle's distance and size.

[0003] In recent years, ultrasonic sensors have been widely used in applications such as parking sensors and detecting obstacles around vehicles, effectively improving driving safety. These applications require ultrasonic sensors to have a large horizontal detection angle and a long detection range. They also require a small vertical detection angle (θ) to reduce false alarms caused by ground reflections. Figure 1 The vertical detection angle θ of the ultrasonic sensor mounted on the vehicle is shown.

[0004] like Figure 2 and Figure 3 As shown in U.S. patent application Ser. No. 09 / 897,569, entitled "ULTRASOUND SENSOR FOR DISTANCE MEASUREMENT," to achieve asymmetric directivity, the ultrasonic sensor housing 100a is provided with a trapezoidal cavity 11a. The bottom surface of cavity 11a is bonded to a circular piezoelectric plate 20a, which is connected to a wire 201a for signal transmission. The piezoelectric plate 20a is then covered in a sequence of trapezoidal silicone rubber 12a, felt 13a, and cork 14a for insulation, and finally coated with a silicone rubber layer 15a for sealing. The trapezoidal cavity design creates an arched top surface and a flat, ground-level bottom surface within the sensor's vertical detection range. However, the trapezoidal cavity and its filling material increase the difficulty and cost of manufacturing. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide an ultrasonic housing and an ultrasonic sensor thereof, which improve the sound pressure value (SPL) of the sensor while ensuring a large ratio between the horizontal detection angle and the vertical detection angle, and are easy to manufacture.

[0006] In a first aspect, the present invention provides an ultrasonic sensor housing, the housing having a cavity opening at the front end face of the housing, the cross-section of the cavity being rectangular, the cavity being surrounded by a cavity bottom wall, two opposite long side walls and two opposite short side walls, the two long side walls being symmetrically provided with two first recesses, the two first recesses being symmetrically located on both sides of a center line in the short side direction of the cavity, each first recess extending in the depth direction of the cavity, and the edge of each first recess being a circular arc or an elliptical arc.

[0007] In a second aspect, the present invention further provides an ultrasonic sensor comprising a piezoelectric element and the ultrasonic sensor housing described above; the piezoelectric element is disposed in a cavity of the ultrasonic sensor housing and fixed to a bottom wall of the cavity.

[0008] The present invention has at least the following advantages:

[0009] 1. The ultrasonic sensor housing of the embodiment of the present invention, by symmetrically providing two first recesses on the two long side walls of the rectangular cavity, can increase the sensor's sound pressure while ensuring a large ratio between the horizontal and vertical detection angles. This increases the sensor's detection range while reducing false alarms caused by ground-reflected wave signals.

[0010] 2. The cavity of the ultrasonic sensor housing of the embodiment of the present invention is rectangular in shape, and the first recess is arc-shaped or elliptical-shaped, which is easy to manufacture and can reduce manufacturing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 Shows the vertical detection angle of the ultrasonic sensor installed on the vehicle.

[0012] Figure 2 and Figure 3 A top view and a cross-sectional view of an existing ultrasonic sensor are respectively shown.

[0013] Figure 4 FIG1 schematically shows a top view of an ultrasonic sensor housing according to a first embodiment of the present invention.

[0014] Figure 5 A schematic diagram of an ultrasonic sensor housing with a rectangular cavity is shown.

[0015] Figure 6 and Figure 7 Schematically showing a perspective view and a top view of an ultrasonic sensor housing according to a second embodiment of the present invention.

[0016] Figure 8 and Figure 9 The cross-sectional views of the ultrasonic sensor housing according to the second embodiment of the present invention are schematically shown from different angles. DETAILED DESCRIPTION

[0017] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0018] Figure 4 Schematically shows a top view of an ultrasonic sensor housing according to a first embodiment of the present invention, see Figure 4 The ultrasonic sensor housing 100 according to the first embodiment of the present invention comprises a cavity 10 opening at the front end 101 of the housing. The cross-section of the cavity 10 is generally rectangular. In this embodiment, each short side of the rectangle is shaped like a convex circular arc, and the long side and the short side of the rectangle are transitioned by a circular arc, and the two short sides are symmetrical. In other embodiments, each short side of the rectangle is shaped like a straight line.

[0019] The cavity 10 is enclosed by a bottom wall, two opposing long sidewalls 11, and two opposing short sidewalls 12. The two long sidewalls 11 are each provided with two first recesses 111, symmetrically disposed about the long-side centerline X of the cavity 10. The two first recesses 111 are symmetrically located on either side of the short-side centerline Y of the cavity 10. Each first recess 111 extends along the depth of the cavity 10, and each first recess 111 has an arc-shaped edge. The long-side centerline X, serving as the rectangle's axis of symmetry, passes through the midpoints of the rectangle's two short sides, while the short-side centerline Y passes through the midpoints of the rectangle's two long sides.

[0020] In this embodiment, each first recess 111 extends continuously along the entire depth direction of the cavity 10, that is, the extension length of the first recess 111 is equal to the depth of the cavity 10, one end of the first recess 111 opens at the front end surface 101 of the shell, and the other end extends to the bottom wall of the cavity.

[0021] In this embodiment, the distance d between the center lines of the two first recesses 111 is 2 mm to 6 mm, so that the ultrasonic wave generated by the ultrasonic sensor has a greater sound pressure.

[0022] In this embodiment, the edges of every two opposite first recesses 111 are located on the circumference of the same circle C1 .

[0023] The material of the ultrasonic sensor housing 100 is metal. In this embodiment, the material of the ultrasonic sensor housing is aluminum.

[0024] When the cross section of the cavity of the ultrasonic sensor housing is circular, the horizontal detection angle of the ultrasonic sensor is the same as the vertical detection angle. When the cross section of the cavity 10 of the ultrasonic sensor housing is rectangular, the horizontal detection angle of the ultrasonic sensor is greater than the vertical detection angle.

[0025] Table 1 shows the Figure 5The simulation results for an ultrasonic sensor with a rectangular cavity and an ultrasonic sensor with a circular cavity are shown. The rectangular cavity has a length L of 13.5 mm, a width W of 7.9 mm, and a diameter of 10 mm. The displacement in the table refers to the vibration displacement of the ultrasonic sensor at a certain frequency during the simulation. The displacement is proportional to the sound pressure of the ultrasonic wave generated by the ultrasonic sensor.

[0026] Table 1

[0027]

[0028] When the cross-section of the cavity 10 is rectangular, regardless of the diameter of the circle C1 where the first recess 111 is located (the diameter of the circle C1 and the center line of the first recess 111 are on the same straight line), the sound pressure value (SPL) of the ultrasonic sensor can be effectively increased while having little effect on the directivity of the ultrasonic sensor.

[0029] Table 2 and Table 3 respectively show simulation results of the ultrasonic sensor having the ultrasonic sensor housing according to the first embodiment of the present invention, wherein the length L of the rectangular cavity is 13.5 mm, and the width W of the rectangular cavity is 7.9 mm.

[0030] Table 2

[0031]

[0032] Comparing Table 1 and Table 2, we can see that when Figure 5 After two first recesses 111 are added to the two long side walls of the rectangular cavity, if the diameter of the circle C1 where the first recess 111 is located is set to 8.5 mm (the diameter tolerance is set to ±0.02 mm), the displacement of the ultrasonic sensor increases from 7.59 μm to 8.68 μm, an increase of 14.36% in displacement, and the sound pressure value increases from 105 dB to 108.35 dB, an increase of 3.19% in sound pressure. At the same time, the ratio of the horizontal detection angle to the vertical detection angle of the ultrasonic sensor does not change much, and the vertical detection angle increases slightly, from 48.89° to 51.48°, a slight increase of 2.59°.

[0033] Table 3

[0034]

[0035] Table 3 shows the simulation results obtained when the diameter of the circle C1 containing the first recesses 111 of the ultrasonic sensor housing 100 is set to 8.5 mm (with a diameter tolerance of ±0.02 mm). As can be seen from Table 3, a 2 mm spacing d between the centerlines of the two first recesses 111 results in a higher SPL, but also a larger vertical detection angle. To minimize the vertical detection angle of the ultrasonic waves generated by the ultrasonic sensor while maintaining a high sound pressure, in one specific embodiment, the spacing d within the ultrasonic sensor housing 100 is set to 5 mm.

[0036] Figures 6 to 9 The schematic diagram shows the structure of an ultrasonic sensor housing according to a second embodiment of the present invention. The main difference between this second embodiment and the first embodiment is that a second recess 112 is symmetrically provided on each of the two long side walls 11 of the cavity 10. Each second recess 112 extends from the front end 101 of the housing along the depth direction of the cavity 10. The extension length of the second recess 112 (i.e., the depth of the second recess 112) is less than the depth of the cavity 10, ranging from 2 mm to 6 mm. The edge of each second recess 112 is arc-shaped, and the depth d2 of the second recess 112 into the long side wall 11 is greater than the depth d1 of the first recess 111 into the long side wall 11. One end of each first recess 111 opens to the bottom end surface 113 of the second recess 112 on the same side as the first recess 111, and the other end of each first recess 111 extends to the cavity bottom wall 102.

[0037] In this embodiment, the center line of each second recess 112 is located on the same straight line as the short-side center line Y of the cavity 10. The edges of the two second recesses 112 are located on the circumference of the same circle C2.

[0038] The second recess 112 increases the space required for automated equipment manufacturing, facilitates the manufacture of the ultrasonic sensor housing, and can increase the sound pressure value and fine-tune the frequency of the sensor while maintaining a certain ratio of the horizontal detection angle to the vertical detection angle.

[0039] In the first and second embodiments described above, the ultrasonic sensor housing 100 includes a housing body 1001 and a housing top 1002. The housing body 1001 is cylindrical and includes a base plate 1004 and an annular sidewall 1003, the rear end of which is connected to the base plate 1004. The housing top 1002 is connected to the front end of the annular sidewall 1003, and the diameter of the housing top 1002 is larger than that of the housing body 1001. In other embodiments, the ultrasonic sensor housing 100 is shaped like a standard cylinder.

[0040] In one specific embodiment, the ultrasonic sensor housing 100 is used in a vehicle ultrasonic ranging sensor. The diameter D1 of the housing body 1001 is 15.4 mm to 15.5 mm, the diameter D2 of the housing top 1002 is 17.5 mm to 17.6 mm, and the overall height H of the ultrasonic sensor housing 100 is 9.6 mm to 9.7 mm. The width of the cavity 10 is less than 9 mm, and the diameter of the circle C2 containing the two second recesses 112 is 9 mm to 12 mm.

[0041] Table 4 shows simulation results of an ultrasonic sensor having an ultrasonic sensor housing according to the second embodiment of the present invention. The length L of the rectangular cavity is 13.5 mm, the width W of the rectangular cavity is 7.9 mm, the diameter of the circle C1 in which the first recess 111 is located is 8.5 mm, the spacing d between the centerlines of the two first recesses 111 is 5 mm, and the extension length of the second recess 112 is 5 mm.

[0042] Table 4

[0043]

[0044] As shown in Table 4, the larger the diameter of circle C2 (i.e., the closer the diameter of circle C2 is to the width of the rectangular cavity), the greater the frequency drop, the larger the vertical detection angle, and the higher the SPL. To minimize the vertical detection angle of the ultrasonic wave generated by the ultrasonic sensor while maintaining a higher sound pressure, in one specific embodiment, the diameter of circle C2 (where the second recess 112 is located) is set to 11 mm. This results in an intermediate SPL, and the sound pressure increases from 108.35 dB (without the second defect 112) to 108.94 dB. This fine-tunes the sensor's frequency, reducing it from 54.22 kHz to 53.91 kHz.

[0045] Table 5 also shows simulation results of an ultrasonic sensor having an ultrasonic sensor housing according to the second embodiment of the present invention. The length L of the rectangular cavity is 13.5 mm, the width W of the rectangular cavity is 7.9 mm, the diameter of the circle C1 in which the first recess 111 is located is 8.5 mm, the spacing d between the centerlines of the two first recesses 111 is 5 mm, and the diameter of the circle C2 in which the second recess 112 is located is 11 mm.

[0046] Table 5

[0047]

[0048] Table 5 shows that when the depth of second recess 112 is between 2 mm and 6 mm, the ultrasonic sensor's frequency, detection angle, and SPL change slightly. However, if second recess 112 extends to the cavity bottom wall, both the horizontal and vertical detection angles increase, causing the frequency to drop sharply to 43.34 kHz and the vertical detection angle to increase significantly by approximately 20°.

[0049] In the simulations of Tables 1 to 5, the overall height of the ultrasonic sensor housing is set to 9.6 mm, the diameter D1 of the housing body 1001 is set to 15.5 mm, and the diameter of the housing top 1002 is set to 17.5 mm.

[0050] In some other embodiments, the edge shape of each first recess 111 is set to an elliptical arc. Alternatively, the edge shape of each first recess 111 can be set to a circular arc, and the shape of each second recess 112 can be set to an elliptical arc, or the edge shape of each first recess 111 and each second recess 112 can be set to an elliptical arc.

[0051] When the ultrasonic sensor housing 100 is assembled into an ultrasonic sensor, the piezoelectric element is disposed within the cavity 10 of the ultrasonic sensor housing 100 and secured to the planar bottom wall 102 of the cavity. The securing methods include, but are not limited to, bonding and welding. The piezoelectric element can be, for example, a piezoelectric ceramic sheet.

[0052] The ultrasonic sensor housing of the embodiment of the present invention symmetrically provides two first recesses on the two long side walls of the rectangular cavity, thereby increasing the sound pressure value of the sensor while ensuring a large ratio between the horizontal detection angle and the vertical detection angle. This increases the detection distance of the sensor while reducing false alarms caused by ground reflection wave signals.

[0053] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. An ultrasonic sensor housing, the housing having a cavity opening at a front end of the housing, the cavity having a rectangular cross-section, the cavity being enclosed by a cavity bottom wall, two opposing long side walls, and two opposing short side walls, characterized in that: Two first recesses are symmetrically provided on the two long side walls, and the two first recesses are symmetrically located on both sides of the center line of the short side direction of the cavity. Each first recess extends along the depth direction of the cavity, and the edge of each first recess is an arc shape or an elliptical arc shape; wherein, when the edge of each first recess is an arc shape, the edges of every two opposite first recesses are located on the circumference of the same circle.

2. The ultrasonic sensor housing according to claim 1, wherein: Each of the first recesses extends continuously along the entire depth direction of the cavity.

3. The ultrasonic sensor housing according to claim 1, wherein: The distance between the center lines of the two first recesses is 2 mm to 6 mm.

4. The ultrasonic sensor housing according to claim 1, wherein: A second recess is symmetrically provided on each of the two long side walls. Each second recess extends from the front end surface of the shell along the depth direction of the cavity, and the extension length of the second recess is less than the depth of the cavity, and the extension length of the second recess is 2 mm to 6 mm. The edge of each second recess is an arc or an elliptical arc, and the depth of the second recess into the long side wall is greater than the depth of the first recess into the long side wall. One end of each of the first recesses opens to the bottom end surface of the second recess located on the same side as the first recess, and the other end of each of the first recesses extends to the bottom wall of the cavity.

5. The ultrasonic sensor housing according to claim 4, characterized in that: The center line of each of the second recesses and the center line of the short side of the cavity are located on the same straight line.

6. The ultrasonic sensor housing according to claim 4, characterized in that The ultrasonic sensor housing includes a cylindrical housing body, the diameter of the housing body is 15.4 mm to 15.5 mm, and the width of the cavity is less than 9 mm; The diameter of the circle where the two second recesses are located is 9 mm to 12 mm.

7. The ultrasonic sensor housing according to claim 1, wherein: Each short side of the rectangle is in the shape of an arc convex outward.

8. The ultrasonic sensor housing according to claim 1, wherein: The ultrasonic sensor housing is made of metal.

9. An ultrasonic sensor comprising a piezoelectric element, characterized in that: The ultrasonic sensor comprises an ultrasonic sensor housing according to any one of claims 1 to 8; The piezoelectric element is disposed in the cavity of the ultrasonic sensor housing and fixed to the bottom wall of the cavity.

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