Ultrasonic sensor device and vehicle

Abstract

An ultrasonic sensor according to an embodiment of the present invention is provided with a bottomed cylindrical case. The case includes a first thin wall section formed along the inner wall surface of the case, a first thick wall section having a first protrusion protruding toward the internal space in the case from the inner wall surface of the case, a second thin wall section formed along the inner wall surface of the case, and a second thick wall section having a second protrusion protruding toward the internal space in the case from the inner wall surface of the case. In a cross section parallel to the inner bottom surface of the case, the first thin wall section and the second thin wall section face each other, the first thick wall section and the second thick wall section face each other, and all or part of the first protrusion and the second protrusion is a quadratic curve shape.

Description

[Technical field]

[0001] The present disclosure relates to an ultrasonic sensor device that transmits and / or receives ultrasonic waves, and a vehicle. [Background technology]

[0002] 2. Description of the Related Art Conventionally, ultrasonic sensors that are attached to the rear end of a vehicle and detect obstacles behind the vehicle are known (for example, see Patent Document 1).

[0003] The ultrasonic sensor in Patent Document 1 includes a cylindrical case with a bottom, a piezoelectric element, a pair of lead wires, and a filler. The piezoelectric element is installed on the inner bottom surface of the case, and the filler seals the case. The pair of lead wires supplies power to the piezoelectric element. The inner diameter of the cylindrical case with a bottom has two protrusions facing each other, and each protrusion has a tip. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2016 / 189858 Summary of the Invention

[0005] The problem to be solved by the present disclosure is to provide an ultrasonic sensor that has wide directivity in the horizontal direction and extremely narrow directivity in the vertical direction.

[0006] 1. An ultrasonic sensor according to an embodiment of the present disclosure Device The present invention includes a cylindrical case having a bottom, the case having a first thin wall portion formed along an inner wall surface of the case, and a second thin wall portion formed along an inner wall surface of the case. らケ (This part seems to be incorrect or unclear in Japanese. Maybe it's a misspelling. For now, it remains as it is.) The case has a first thick wall portion having a first protrusion protruding toward the internal space of the case, a second thin wall portion formed along the inner wall surface of the case, and a second thick wall portion having a second protrusion protruding from the inner wall surface of the case toward the internal space of the case. A ultrasonic sensor device that, in a cross-section parallel to the inner bottom surface of the case, the first thin-walled portion and the second thin-walled portion face each other, the first thick-walled portion and the second thick-walled portion face each other, and all or part of the first protrusion and the second protrusion are has an elliptical shape as follows. Let the direction in which a wide-angle directivity is required for the directivity characteristics of the ultrasonic sensor device be X, the direction in which a narrow-angle directivity is required for the directivity characteristics of the ultrasonic sensor device be Y, the diameter in the X direction of the ellipse be DX, the diameter in the Y direction of the ellipse be DY, and for the internal space of the case, when the opening length from the first thin wall part to the second thin wall part is B, DX has a length of 20.5% or more of B, and DY has a length of 34.1% or more of B.

Brief Description of the Drawings

[0007]

Figure 1A

Figure 1B

Figure 1C

Figure 2A

Figure 2B

Figure 2C

Figure 2D

Figure 3

Figure 4A

Figure 4B

Figure 4C

Figure 5A

Figure 5B

Figure 6A

Figure 6B

Mode for Carrying Out the Invention

[0008] Hereinafter, each embodiment of the present disclosure will be described with reference to the drawings.

[0009] (Embodiment) It is desirable that the ultrasonic sensor widens the transmission and reception range of ultrasonic waves in the horizontal direction, detects obstacles far from the vehicle, narrows the directivity in the vertical direction, and does not detect reflections from the ground or ceiling.

[0010] However, when a conventional ultrasonic sensor attempts to increase the output of ultrasonic waves to detect obstacles at a long distance from the rear end of the vehicle, the detection range in the vertical direction also increases, and reflections from the ground or ceiling are detected. There is a need for an ultrasonic device that has a wide directivity in the horizontal direction and an extremely narrow directivity in the vertical direction, which improves the above points.

[0011] In the past, in such an ultrasonic device, for example, when the horizontal half-value angle is 63 degrees or more, it is desirable that the vertical half-value angle is 35 degrees or less, and when the horizontal half-value angle is 80 degrees or more, the vertical half-value angle is 41 degrees or less. That is, it has been required to achieve a flatness ratio (horizontal half-value angle ÷ vertical half-value angle) of 2 or more.

[0012] However, in recent years, there has been an increasing number of cases where further improvement in the flatness ratio is required. For example, there are many cases where a flatness ratio of 2.5 or more and a vertical half-value angle of 35 degrees or less are required. Thus, it is required to provide an ultrasonic device that can achieve a wide directivity in the horizontal direction and an even narrower directivity in the vertical direction.

[0013] FIG. 1A is a perspective view of the ultrasonic device 11 in the embodiment. FIG. 1B is a cross-sectional view of the ultrasonic device 11 in the embodiment. FIG. 1C is a cross-sectional view taken along a direction perpendicular to the cross-section of FIG. 1B in the embodiment. In FIG. 1A, the broken line is a hidden line indicating a portion that is hidden and not visible.

[0014] The ultrasonic device 11 of the present disclosure includes a bottomed cylindrical case 12, a piezoelectric element 13, a lead wire 14, and a filler 15. The piezoelectric element 13 is installed on the inner bottom surface of the case 12. The lead wire 14 is connected to the piezoelectric element 13. The filler 15 seals the case 12.

[0015] The case 12 has a first thin wall portion 21A and a first thick wall portion 22A. The first thin wall portion 21A is formed along the inner wall surface of the case 12. The first thick wall portion 22A has a first protruding portion 24A protruding from the inner wall surface of the case 12 toward the inner space of the case 12.

[0016] The case 12 has a bottomed cylindrical shape and has a bottom portion 16 and a cylindrical portion 17. The case 12 is formed of a metal such as aluminum, for example. The bottom portion 16 is a vibration surface that transmits ultrasonic waves and has an inner bottom surface 19 and an outer bottom surface 20. The cylindrical portion 17 has a pair of opposed thin wall portions 21 and a pair of opposed thick wall portions 22. That is, in FIG. 1A, the cylindrical portion 17 has a first thin wall portion 21A and a second thin wall portion 21B. The first thin wall portion 21A and the second thin wall portion 21B are formed along the inner wall surface of the case 12.

[0017] Furthermore, the cylindrical portion 17 has a first thick wall portion 22A and a second thick wall portion 22B. The first thick wall portion 22A has a first protruding portion 24A protruding from the inner wall surface of the case 12 toward the inner space of the case 12. The second thick wall portion 22B has a second protruding portion 24B protruding from the inner wall surface of the case 12 toward the inner space of the case 12.

[0018] The outer shape of the first protruding portion 24A includes a first ellipse 25A having a center point 28A, and has a shape in which a first tangent line 26A-1 that contacts at a contact point 27A-1 of the ellipse 25A and a second tangent line 26A-2 that contacts at a contact point 27A-2 of the first ellipse 25A spread toward the outer periphery.

[0019] The outer shape of the second protrusion 24B includes a second ellipse 25B with a center point 28B, and has a shape in which a first tangent line 26B-1 that contacts at the contact point 27B-1 of the second ellipse 25B and a second tangent line 26B-2 that contacts at the contact point 27B-2 of the second ellipse 25B spread toward the outer periphery.

[0020] Here, the first thin-walled portion 21A and the second thin-walled portion 21B are collectively referred to as the thin-walled portion 21. The first thick-walled portion 22A and the second thick-walled portion 22B are collectively referred to as the thick-walled portion 22. The first protrusion 24A and the second protrusion 24B are collectively referred to as the protrusion 24. The first ellipse 25A and the second ellipse 25B are collectively referred to as the ellipse 25. The first ellipse center point 28A and the second ellipse center point 28B are collectively referred to as the ellipse center point 28. The first tangent line 26A-1 and the second tangent line 26A-2 of the first ellipse 25A and the first tangent line 26B-1 and the second tangent line 26B-2 of the second ellipse 25B are collectively referred to as the tangent line 26.

[0021] The thin-walled portion 21 is a portion with a relatively thin wall thickness and has a substantially arc shape with a substantially constant wall thickness. Here, it is desirable that the thickness of the thin-walled portion 21 be in the range of ±10% or less with respect to the average thickness of the thin-walled portion 21.

[0022] The piezoelectric element 13 is a source of ultrasonic vibration fixed to the inner bottom surface 19 of the case 12 and has a piezoelectric body (not shown) and electrodes (not shown) provided on both surfaces thereof. A pair of lead wires 14 are formed of a conductor. Electrodes (not shown) are formed on both surfaces of the piezoelectric element 13. At least one of the lead wires 14 is connected to one electrode of the piezoelectric element 13. Electric power is supplied to the piezoelectric element 13 by the pair of lead wires 14.

[0023] The filler 15 is made of a resin material such as a foamed silicone resin, etc., and seals the piezoelectric element 13 inside the case 12.

[0024] Next, the structure of the case 12 will be described with reference to FIGS. 2A to 2D and FIG. 3. FIG. 2A is a top view of the case 12 of the ultrasonic device 11 in the embodiment. FIG. 2B is a side view of the case 12 of the ultrasonic device 11 in the embodiment.

[0025] Figure 2C is a front view of the case 12 of the ultrasonic device 11 in the embodiment. Figure 2D is a perspective view of the case 12 of the ultrasonic device 11 in the embodiment. Figure 3 is a cross-sectional view of the case 12 of the ultrasonic device 11 in the embodiment. Figure 3 substantially coincides with a cross-sectional view of the cylindrical portion 17 of the case 12 when the case 12 is cut by a plane parallel to the inner bottom surface 19.

[0026] As shown in FIGS. 2A and 1C, the case 12 has a center point 23. Also, as shown in FIGS. 1A, 2A to 2C, in the ultrasonic device 11, the X direction, the Y direction, and the Z direction are defined.

[0027] In FIG. 2A, the location where the piezoelectric element 13 is disposed with respect to the inner bottom surface 19 of the case 12 is indicated by a rectangular broken line. The piezoelectric element 13 is disposed such that the center of the inner bottom surface 19 of the case 12 substantially coincides with the center of the piezoelectric element 13.

[0028] As shown in FIG. 3, the dimensions of the case 12 are represented as the outer diameter A of the cylindrical portion 17, the opening length B of the thin-walled portion 21, the minimum opening length C of the thick-walled portion 22, the wall thickness D of the thin-walled portion 21, the X-direction diameter DX of the ellipse of the thick-walled portion 22, the Y-direction diameter DY of the ellipse of the thick-walled portion 22, and the X-direction length LC from the contact point 27 where the ellipse 25 and the tangent line 26 are in contact to the ellipse center line.

[0029] FIG. 4A is a block diagram of the ultrasonic sensor 30 of the present embodiment. FIG. 4B is a block diagram of another ultrasonic sensor 30 of the present embodiment. The ultrasonic sensor 30 includes an ultrasonic device 11, a transmission circuit 71, and a housing case 73. The ultrasonic device 11 is used as an ultrasonic transducer. The transmission circuit 71 drives the ultrasonic device 11 to generate ultrasonic waves. The housing case 73 holds the ultrasonic device 11 and the transmission circuit 71.

[0030] Here, as shown in FIG. 4B, the housing case 73 may hold only the ultrasonic device 11. That is, the housing case 73 may be configured to hold at least the ultrasonic device 11.

[0031] FIG. 4C is a schematic diagram of a vehicle 31 equipped with the ultrasonic sensor 30 of the present embodiment. The ultrasonic sensor 30 transmits ultrasonic waves and receives the reflected ultrasonic waves, thereby detecting the presence of obstacles and the like around the vehicle 31 and detecting the distance to the obstacles.

[0032] In FIG. 1A, the X direction and Y direction of the ultrasonic device 11 are shown horizontally, and the Z direction is shown vertically. However, when installed in the vehicle 31, it is installed such that the Y direction of the ultrasonic device 11 becomes the vertical direction (i.e., the substantially vertical direction), and the X direction becomes the horizontal direction (i.e., the substantially horizontal direction).

[0033] That is, it is installed such that the X direction and Z direction of the ultrasonic device 11 are substantially horizontal with respect to the ground, and the Y direction is substantially vertical. Here, the direction in which ultrasonic waves are transmitted or received is the Z direction.

[0034] By setting the direction of the ultrasonic device 11 in this way and defining the shape of the ultrasonic device 11, it is possible to control the directivity in the horizontal direction while ensuring the narrow directivity in the vertical direction.

[0035] Note that a slight angle may be provided for the Z direction with respect to the horizontal direction of the vehicle 31. Also, the Y direction may have a slight angle with respect to the vertical direction. Further, the direction in which ultrasonic waves are transmitted or received may be slightly inclined upward or downward from the horizontal.

[0036] Here, the directivity of the ultrasonic device 11 is the directivity of the ultrasonic reception sensitivity when the ultrasonic device 11 is used for ultrasonic reception, and is the directivity of the ultrasonic radiation intensity when the ultrasonic device 11 is used for ultrasonic transmission.

[0037] (Table 1) shows the evaluation results of the examples considered in this embodiment.

[0038] In Examples 1 to 50 shown in (Table 1), the outer diameter A of the cylindrical portion 17 is 15.5 mm. The opening length B of the thin-walled portion 21 is 14.62 mm. The wall thickness D of the thin-walled portion 21 is 0.44 mm. The minimum opening length C of the thick-walled portion 22 is 6.6 mm, the diameter DX in the X direction of the ellipse 25 of the protruding portion 24 of the thick-walled portion 22 is 2.0 mm or more and 8.0 mm or less, the diameter in the Y direction is 3.0 mm or more and 9.0 mm or less, and the tangent line 26 of the ellipse 25 forming the protruding portion 24 is at the contact point 27 on the ellipse 25 at a distance (referred to as LC) of 0.8 mm in the X direction from the center line passing through the center point 28 of the ellipse 25.

[0039] However, when the contact point 27 cannot exist inside the thin-walled portion 21 of the cylindrical portion 17, the shape of the protruding portion 24 shall be a shape consisting only of the ellipse 25.

[0040]

Table 1

[0041] (Table 1) shows the dimensions of DX and DY in Case 12, and the vertical directivity angle, horizontal directivity angle, and flatness ratio (horizontal directivity angle ÷ vertical directivity) at the half value (-6 dB) with respect to the maximum output when ultrasonic radiation is performed. In all of No1 to No50, the flatness ratio exceeds 2.5. Examples with a flatness ratio exceeding 2.5 are represented as "G (Good)", and among them, examples with a vertical directivity angle of 35 degrees or less are represented as "E (Excellent)". In other words, it shows that just including the ellipse 25 in the outer shape of the protruding portion 24 results in a good flatness ratio.

[0042] Also, (Table 2) is obtained by rearranging (Table 1) along the DX and DY axes.

[0043]

Table 2

[0044] From (Table 2), it was found that the good directivity characteristic "E" depends on DX and DY. Good directivity angle characteristics can be obtained when DX is 3.0 mm or more, that is, has a length of 20.5% or more of the opening length B of the thin wall portion 21, and DY is 5.0 mm or more, that is, has a length of 34.1% or more of the opening length B of the thin wall portion 21.

[0045] Furthermore, when examining the distribution of "E", it was found that it is concentrated in the range of 2 mm, that is, 13.6% of the opening length B of the thin wall portion 21, mainly when the relationship of a linear function where the slope of DY with respect to DX is 0.5 and the offset is 4.0 mm, that is, 27.3% of the opening length B of the thin wall portion 21, holds.

[0046] When expressed by a mathematical formula, a narrow-angle directivity in the vertical direction can be obtained when the relationship of DY - B×0.136 < (DX×0.5 + B×0.273) < DY + B×0.136 is satisfied.

[0047] (Modification Example 1) Note that the outer shapes of the first protruding portion 24A and the second protruding portion 24B are not limited to ellipses. As shown in FIGS. 5A and 5B, they may be parabolas. The first tangent line 26C-1 and the second tangent line 26C-2 of the parabola have a shape that spreads toward the outer periphery. Here, the outer shapes of the first protruding portion 24A and the second protruding portion 24B may be quadratic curves, the outer shape may be a circle, or the outer shapes of the first protruding portion 24A and the second protruding portion 24B may be hyperbolas. Also, at least one of the outer shapes of the first protruding portion 24A and the second protruding portion 24B may be a quadratic curve shape.

[0048] (Modification Example 2) Also, there may be cases where the tips of the first protruding portion 24A and the second protruding portion 24B are flat. In FIGS. 6A and 6B, the protruding portion tips 40A and 40B of the protruding portions 24A and 24B are flat, and the protruding portion side wall portions 41A-1, 41A-2 and 41B-1, 41B-2 of the protruding portions 24A and 24B may be quadratic curves 25A and 25B, and cases of circles, ellipses, hyperbolas, or parabolas are conceivable. Also, there may be cases where the lead wire 14 is joined to the protruding portion 24A or the protruding portion 24B.

[0049] In addition, in the present embodiment, the thicknesses of the first thick wall portion 22A and the second thick wall portion 22B do not change in the Z direction of the ultrasonic device 11. However, the present disclosure is not limited thereto. In the ultrasonic device of the present disclosure, the thickness of the thick wall portion may change midway in the Z direction, or the thick wall may disappear midway. It is only necessary that at least a part of the ultrasonic device forms a thick wall portion in the Z direction.

[0050] The ultrasonic device of the present disclosure includes a bottomed cylindrical case 12, a piezoelectric element 13, a lead wire 14, and a filling material 15. The piezoelectric element 13 is installed on the inner bottom surface 19 of the case 12. The lead wire 14 is connected to the piezoelectric element 13. The filling material 15 seals the case 12.

[0051] The case 12 has a first thin wall portion 21A, a first thick wall portion 22A, a second thin wall portion 21B, and a second thick wall portion 22B. The first thin wall portion 21A and the second thin wall portion 21B are formed along the inner wall surface of the case 12. The first thick wall portion 22A has a first protruding portion 24A protruding from the inner wall surface of the case 12 toward the internal space of the case 12. The second thick wall portion 22B has a second protruding portion 24B protruding from the inner wall surface of the case 12 toward the internal space of the case 12.

[0052] Also, the first thick wall portion 22A has a first protruding portion 24A protruding from the inner wall surface of the case 12 toward the internal space of the case 12, and the second thick wall portion 22B has a second protruding portion 24B protruding from the inner wall surface of the case 12 toward the internal space of the case 12.

[0053] The outer shape of the first protruding portion 24A includes a first ellipse 25A, and has a shape in which the first tangent line 26A-1 and the second tangent line 26A-2 spread toward the outer periphery. Also, the outer shape of the second protruding portion 24B includes a second ellipse 25B. The first tangent line 26B-1 and the second tangent line 26B-2 have a shape that spreads toward the outer periphery.

[0054] Assume the direction for obtaining wide directivity is the X direction, and the direction for obtaining narrow directivity is the Y direction. Let the diameter in the X direction of the ellipse 25A or the ellipse 25B be DX, the diameter in the Y direction be DY, and the opening length of the thin-walled portion 21 be B. Then, DX has a length of 20.5% or more of B, and DY satisfies a length of 34.1% or more of B.

[0055] Furthermore, when DX and DY satisfy the relationship of DY - B×0.136 < (DX×0.5 + B×0.273) < DY + B×0.136, a narrower directivity in the Y direction can be obtained.

[0056] As described above, the ultrasonic device 11 of the present embodiment has a piezoelectric element 13 on the inner bottom surface 19 of the bottomed cylindrical case 12. And the cylindrical portion 17 of the case 12 has, in a cross section parallel to the inner bottom surface 19 of the case 12, a thin-walled portion 21 whose inner wall surface is a substantially arc shape centered on the center point 23 of the case 12, and a thick-walled portion 22 having a wall thickness thicker than that of the thin-walled portion 21 and whose inner wall surface protrudes toward the inner space of the case.

[0057] By including the ellipse 25 in the shape of the protruding portion 24, it becomes possible to design a directivity that exceeds the conventional directivity level. As a result, while ensuring a wide directivity in the X direction, an extremely narrow directivity can be realized in the Y direction. By equipping the vehicle 31 with the ultrasonic sensor 30 provided with the ultrasonic device 11 as an ultrasonic transducer and using it for detecting obstacles, the influence due to reflection from the road surface or reflection from the ceiling of a garage or the like can be reduced, and detection with a wide directivity in the horizontal direction becomes possible.

[0058] For example, an obstacle behind the vehicle can be accurately detected. Further, when a narrower directivity in the Y direction is required, it is desirable that the diameter DX in the X direction of the ellipse 25 has a length of 20.5% or more of the opening length B of the thin-walled portion 21, and the diameter DY in the Y direction has a length of 34.1% or more of the opening length B of the thin-walled portion 21.

[0059] Also, when DX and DY satisfy the relationship of DY - B×0.136 < (DX×0.5 + B×0.273) < DY + B×0.136, a narrower directivity in the Y direction can be obtained.

[0060] In addition, in this embodiment, the thickness of the thin-walled portion 21 is made substantially constant, but it is also possible to not be substantially constant. For example, the thickness of the thin-walled portion 21 may have an inclination. With the above configuration, the ultrasonic device and the ultrasonic sensor of the present disclosure have an extremely narrow directivity in the vertical direction while ensuring a wide directivity in the horizontal direction.

Explanation of Signs

[0061] 11 Ultrasonic device 12 Case 13 Piezoelectric element 14 Lead wire 15 Filling material 16 Bottom part 17 Cylindrical part 19 Inner bottom surface 20 Outer bottom surface 21 Thin-walled portion 21A First thin-walled portion 21B Second thin-walled portion 22 Thick-walled portion 22A First thick-walled portion 22B Second thick-walled portion 23 Center point 24 Protrusion 24A First protrusion 24B Second protrusion 25 Ellipse 25A First ellipse 25B Second ellipse 26 Tangent line 26A-1,26B-1 First tangent line 26A-2,26B-2 First tangent line 27 Contact point 27A-1 Contact point 27B-1 Contact point 28A-1 Contact point 28B-1 Contact point 28 Ellipse center point 28A First ellipse center point 28B Second ellipse center point 30 Ultrasonic sensor 31 Vehicle 71 Transmission circuit 73 Housing case A Outer diameter B Opening length C Minimum opening length D Wall thickness DX Diameter DY Diameter

Claims

1. comprising a bottomed cylindrical case, the case having a first thin-walled portion formed along the inner wall surface of the case and a first thick-walled portion having a first protruding portion protruding from the inner wall surface of the case toward the internal space of the case, a second thin-walled portion formed along the inner wall surface of the case, and a second thick-walled portion having a second protruding portion protruding from the inner wall surface of the case toward the internal space of the case, the ultrasonic sensor device comprising: in a cross-section parallel to the inner bottom surface of the case, the first thin-walled portion and the second thin-walled portion face each other, and the first thick-walled portion and the second thick-walled portion face each other, all or part of the first protruding portion and the second protruding portion are in an elliptical shape, taking the direction in which a wide-angle directivity is required for the directivity characteristics of the ultrasonic sensor device as X, taking the direction in which a narrow-angle directivity is required for the directivity characteristics of the ultrasonic sensor device as Y, taking the diameter in the X direction of the ellipse as DX, taking the diameter in the Y direction of the ellipse as DY, and for the internal space of the case, when the opening length from the first thin-walled portion to the second thin-walled portion is B, DX has a length of 20.5% or more of B, and DY has a length of 34.1% or more of B, Ultrasonic sensor device.

2. the shapes of the first protruding portion and the second protruding portion include the ellipse and two tangent lines tangent to the ellipse, and the two tangent lines spread toward the outer periphery, The ultrasonic sensor device according to claim 1.

3. the diameter DX in the X direction of the ellipse and the diameter DY in the Y direction of the ellipse are satisfying the relationship of DY - B×0.136 < (DX×0.5 + B×0.273) < DY + B×0.136, The ultrasonic sensor device according to claim 1.

4. comprising the ultrasonic sensor device according to any one of claims 1 to 3, Vehicle.

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