JP2015059899A - Obstacle detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enlarge detection distance of an obstacle existing in the surroundings in an aerial ultrasonic sensor of an obstacle detection device.SOLUTION: The obstacle detection device comprises: a fitting part having an open hole; and an aerial ultrasonic sensor fixed to the open hole of the fitting part. The aerial ultrasonic sensor is configured so that: an opening of a horn is fixed to a rear part of the open hole of the fitting part; the horn is disposed in front of the sensor; and a resin material is filled inside covering at least the opening of the horn.

Description

  The present invention relates to an obstacle detection device that is attached to, for example, a bumper of a vehicle such as an automobile and detects an obstacle around the vehicle.

  An aerial ultrasonic sensor using a piezoelectric element transmits ultrasonic waves from the aerial ultrasonic sensor into the air, the transmitted ultrasonic waves are reflected by obstacles, etc., propagate in the air, and again by the aerial ultrasonic sensor. It is used in an obstacle detection device that detects an obstacle by receiving it. In the aerial ultrasonic sensor, for example, as disclosed in Patent Document 1, a piezoelectric ceramic element is fixed to a bottom surface of a metal case, and the piezoelectric ceramic element and the case are connected to lead terminals via lead wires, respectively. It becomes the composition.

  As an obstacle detection device using such an aerial ultrasonic sensor, for example, as disclosed in Patent Document 2, a through-hole is formed against a wall member such as a bumper of a vehicle such as an automobile in which the through-hole is formed. There are some which are installed so that the radiation surface of the aerial ultrasonic sensor is exposed from the outside and detects obstacles around the vehicle.

  Moreover, in the obstacle detection device, for example, as disclosed in Patent Document 3, in order to increase the detection distance of the aerial ultrasonic sensor, a horn is attached to the aerial ultrasonic sensor, the directivity is sharpened, and transmission / reception is performed. Some improve sensitivity.

Japanese Utility Model Publication No. 62-177198 JP 2006-298010 A JP 58-85699 A

  In general, the bumper of a vehicle is made of a resin material, and the case portion of the aerial ultrasonic sensor is made of a metal material. For this reason, when it is attached to the bumper part of the vehicle with the radiation surface of the aerial ultrasonic sensor that constitutes the obstacle detection device exposed to the outside, the directivity is too wide and the detection distance of the aerial ultrasonic sensor is sufficient. There is a problem that it cannot be extended.

  In addition, in order to expand the detection distance of the aerial ultrasonic sensor of the obstacle detection device, when a horn is attached to the aerial ultrasonic sensor, a dent is formed in the bumper part of the vehicle. When dust or the like accumulates, there is a problem that the detection performance of the airborne ultrasonic sensor is lowered.

  This invention was made in order to solve such a subject, and it aims at providing the obstruction detection apparatus which can expand the detection distance of an air ultrasonic sensor.

  The obstacle detection device of the present invention is an obstacle detection device comprising an attachment portion provided with a through hole and an aerial ultrasonic sensor fixed to the through hole of the attachment portion, wherein the aerial ultrasonic sensor is The opening of the horn is fixed to the rear of the through hole of the mounting portion through a horn disposed in the front, and the resin material is filled in the interior including at least the opening of the horn.

  According to this invention, there exists an effect that the detection distance of the air ultrasonic sensor of an obstacle detection apparatus can be expanded.

It is the schematic which shows an example of the cross section of the obstruction detection apparatus which concerns on Embodiment 1 of this invention. It is the schematic which shows only the attachment part of the obstruction detection apparatus which concerns on Embodiment 1 of this invention from the front. It is a calculation result which shows an example of the radiation sound pressure distribution of the obstacle detection apparatus which concerns on Embodiment 1 of this invention. It is the schematic which shows an example of the cross section of the obstruction detection apparatus which concerns on Embodiment 3 of this invention. It is the schematic which shows an example of the cross section of the obstruction detection apparatus which concerns on Embodiment 4 of this invention.

  The present invention relates to an obstacle detection device that is attached to, for example, a bumper of a vehicle and detects an obstacle around the vehicle. Hereinafter, the case where the aerial ultrasonic sensor of the obstacle detection device of the present invention is attached to a vehicle will be described.

Embodiment 1 FIG.
An obstacle detection apparatus according to Embodiment 1 of the present invention will be described.

  1 is a schematic diagram showing an example of a cross section of an obstacle detection apparatus according to Embodiment 1 of the present invention. Moreover, FIG. 2 is the schematic which shows only the attachment part of the obstruction detection apparatus based on Embodiment 1 of this invention from the front.

  In the figure, the obstacle detection device includes a mounting portion 1, an aerial ultrasonic sensor 2, and a horn 3. The attachment portion 1 is, for example, a bumper of a vehicle such as an automobile, and is formed of a synthetic resin such as a polypropylene resin. For example, as shown in FIG. 2, the attachment portion 1 is provided with at least one through hole 11 that opens to the front and back. The aerial ultrasonic wave sensor 2 is roughly composed of a case 21 made of a metal such as aluminum, a piezoelectric ceramic 22 and a lead wire 23, and an opening of the horn 3 is opened through a horn 3 disposed in front. It is fixed behind the through hole 11 of the attachment portion 1. The horn 3 is filled with a resin material 4 inside including at least a portion covering the opening.

  In the first embodiment, the aerial ultrasonic sensor 2 to which the horn 3 is attached is attached to the attachment portion 1 so that the opening of the horn 3 is exposed to the outside of the attachment portion 1 through the through hole 11. It is fixed. Since the horn 3 is filled with the resin material 4, the horn 3 and the resin material 4 are part of the mounting portion 1. Since the horn 3 and the resin material 4 are configured to be flush with the external surface of the mounting portion 1, the radiation surface of the airborne ultrasonic sensor is not exposed to the outside, and the vehicle bumper portion Therefore, it is easy to maintain the bumper portion of the vehicle, and it is possible to prevent raindrops, dust, and the like from accumulating in the dent and lower the detection performance of the aerial ultrasonic sensor.

  The aerial ultrasonic sensor 2 applies a voltage to the piezoelectric ceramic 22 via the lead wire 23, thereby exciting the ultrasonic wave, transmitting the ultrasonic wave into the air, and receiving the ultrasonic wave reflected by the obstacle. In this way, obstacles are detected. In this embodiment, the aerial ultrasonic sensor 2 includes a signal processing unit (not shown) that applies a drive voltage to the piezoelectric ceramic and processes a voltage generated by the back electromotive force effect from the piezoelectric ceramic. Is provided. Here, it is assumed that the aerial ultrasonic sensor 2 is attached to at least one position such as the front, rear, or corner of the vehicle so that obstacles around the vehicle can be detected. Of course, a plurality of aerial ultrasonic sensors 2 may be attached at the same time, and the attachment portion 1 is not limited to a vehicle bumper. The aerial ultrasonic sensor 2 may not only detect an obstacle in the horizontal direction but also detect the presence or absence of an obstacle in a desired direction.

  The horn 3 attached in front of the aerial ultrasonic sensor 2 has a cross-sectional area that gradually changes with respect to its length, and is formed of synthetic resin or metal. It is preferably formed of a resin or the like. The inside of the horn 3 is filled with a resin material 4 made of a material different from the synthetic resin constituting the horn 3. By arranging the horn 3 in this way, the ultrasonic wave radiated from the aerial ultrasonic sensor 2 has sharpened directivity and improved transmission / reception sensitivity. The resin material 4 may not be filled in the entire interior of the horn 3, and may be formed so as to cover at least the opening of the horn 3, and the interior of the horn 3 may be hollow.

  Furthermore, although the aerial ultrasonic sensor 2 is attached so that the horn 3 and the resin material 4 are exposed from the through-hole 11 of the attachment part 1 of the bumper, the attachment part 1, the horn 3 and the resin material 4 are all resin materials. Therefore, even when the paint is applied, the color developability is unlikely to occur, visibility from the outside can be reduced, and appearance (design) can be improved.

  FIG. 3 is a calculation result showing an example of a radiation sound pressure distribution of the obstacle detection device according to Embodiment 1 of the present invention. Here, in the calculation of the radiation sound pressure, it is assumed that the horn 3 is acrylic and the resin material 4 is epoxy. In the drawing, the horizontal axis indicates the angle when the front direction of the aerial ultrasonic sensor is 0 °. The vertical axis indicates the sound pressure level, which is normalized by the sound pressure level in the front direction in the case of only the aerial ultrasonic sensor 2 without the horn 3 and the resin material 4. The effect of the obstacle detection device can be verified from the calculation result of the radiation sound pressure distribution.

  As shown in FIG. 3, the radiated sound pressure in the front direction is +15 dB compared to the case of only the aerial ultrasonic sensor 2 without the horn 3 and the resin material 4, and the horn 3 and the resin material 4 are It can be confirmed that the transmission sensitivity is improved by attaching it in front of the acoustic wave sensor 2.

  The horn 3 gradually changes in cross-sectional area with respect to the length of the horn, and various shapes are conceivable depending on how the cross-sectional area changes. In this embodiment, a conical horn having a linear shape in cross section is shown, but the present invention is not limited to this. A cylindrical horn having no change in cross section with respect to the length, and a parabolic in which the cross section increases in proportion. The same effect can be obtained for an horn, an exponential horn whose cross-sectional area increases with an exponential function, and the like.

  As described above, according to the first embodiment of the present invention, the aerial ultrasonic sensor 2 is attached so that the horn 3 and the resin material 4 are exposed from the through hole of the attachment part 1 of the bumper to which the obstacle detection device is attached. Therefore, there is an effect that the detection distance of the airborne ultrasonic sensor of the obstacle detection device can be increased.

  Further, according to the first embodiment of the present invention, when the aerial ultrasonic sensor of the obstacle detection device is attached to the bumper portion of the vehicle, the radiating surface is exposed to the outside or the horn is recessed. Since the vehicle bumper portion is not in a state, maintenance of the vehicle bumper portion is facilitated, the deterioration of the detection performance of the aerial ultrasonic sensor can be suppressed, and the appearance (designability) of the mounting portion can be improved.

Embodiment 2. FIG.
In Embodiment 1 of the present invention, it has been described that the transmission sensitivity of the obstacle detection device is improved by attaching the horn 3 and the resin material 4 to the front of the aerial ultrasonic sensor 2. Next, in Embodiment 2 of the present invention, an obstacle detection device that matches the acoustic impedance of the airborne ultrasonic sensor 2 and the acoustic impedance of air by setting the acoustic impedance of the resin material 4 will be described. .

  In the obstacle detection device of the second embodiment, when the acoustic impedance of air is Za, the acoustic impedance of the airborne ultrasonic sensor is Zs, and the acoustic impedance of the resin material 4 filling the horn 3 is Zm, the equation (1) A resin material having acoustic impedance is selected so as to satisfy the relationship.

  By setting the acoustic impedance of the resin material 4 as described above, matching between the acoustic impedance of the airborne ultrasonic sensor 2 and the acoustic impedance of air is improved.

  Furthermore, you may select the resin material which has an acoustic impedance which satisfy | fills the relationship of Formula (2), satisfy | filling the relationship of Formula (1).

  By setting the acoustic impedance of the resin material 4 as described above, the acoustic impedance of the aerial ultrasonic sensor 2 and the acoustic impedance of the air can be better matched.

  Since the acoustic impedance matching is improved, reflection of ultrasonic waves at the boundary between the aerial ultrasonic sensor 2 and the resin material 4 and the boundary between the resin material 4 and the air can be suppressed, and the propagation efficiency of the ultrasonic waves is increased. The sensitivity of the aerial ultrasonic sensor 2 is improved and the detection distance is expanded.

  As described above, according to the second embodiment of the present invention, as in the first embodiment of the present invention, the horn 3 and the resin material 4 are exposed from the through hole of the bumper mounting portion 1 for mounting the obstacle detection device. Thus, since the aerial ultrasonic sensor 2 is attached, the detection distance of the aerial ultrasonic sensor of the obstacle detection device can be increased.

  According to the second embodiment of the present invention, the acoustic impedance of the resin material 4 is set to match the acoustic impedance of the aerial ultrasonic sensor 2 with the acoustic impedance of the air. 2 and the boundary between the resin material 4 and the boundary between the resin material 4 and the air can be suppressed, and the propagation efficiency of the ultrasonic wave can be increased. Therefore, the sensitivity of the aerial ultrasonic sensor 2 is improved and the detection distance is increased. Can be enlarged.

  According to the second embodiment of the present invention, as in the first embodiment of the present invention, when the aerial ultrasonic sensor of the obstacle detection device is attached to the bumper portion of the vehicle, the radiation surface is exposed to the outside. Since the bumper part of the vehicle is easier to maintain, the deterioration of the detection performance of the airborne ultrasonic sensor can be suppressed, and the appearance of the mounting part (design) is improved. Can be made.

Embodiment 3 FIG.
Next, in Embodiment 3 of the present invention, the hollow microcapsule 41 is added to the resin material 4 filled in the horn 3 to achieve matching between the acoustic impedance of the airborne ultrasonic sensor 2 and the acoustic impedance of air. The obstacle detection device will be described.

  FIG. 4 is a schematic view showing an example of a cross section of an obstacle detection device according to Embodiment 3 of the present invention. Since the basic configuration and operation of the obstacle detection device according to Embodiment 3 are the same as those of the obstacle detection device according to Embodiment 1 and Embodiment 2, only different parts will be described.

  The horn 3 constituting the obstacle detection device according to the third embodiment is filled with the resin material 4, and the resin material 4 has a predetermined amount of hollow microcapsules 41 such as glass or organic matter. It has been added. Since the density of the resin material 4 changes according to the addition of the microcapsule 41, the acoustic impedance defined by the product of the density and the speed of sound can be changed. Or the resin material 41 which satisfy | fills Formula (2) can be obtained.

  By adding such a microcapsule 41 and setting the acoustic impedance of the resin material 4, the acoustic impedance of the airborne ultrasonic sensor 2 and the acoustic impedance of the air can be matched.

  Since the acoustic impedance matching is improved, reflection of ultrasonic waves at the boundary between the aerial ultrasonic sensor 2 and the resin material 4 and the boundary between the resin material 4 and the air can be suppressed, and the propagation efficiency of the ultrasonic waves is increased. The sensitivity of the aerial ultrasonic sensor 2 is improved and the detection distance is expanded.

  As described above, according to the third embodiment of the present invention, as in the first embodiment of the present invention, the horn 3 and the resin material 4 are exposed from the through hole of the bumper mounting portion 1 for mounting the obstacle detection device. Thus, since the aerial ultrasonic sensor 2 is attached, the detection distance of the aerial ultrasonic sensor of the obstacle detection device can be increased.

  Further, according to Embodiment 3 of the present invention, the acoustic impedance of the aerial ultrasonic sensor 2 and the acoustic impedance of the air can be matched, and the boundary between the aerial ultrasonic sensor 2 and the resin material 4 and the resin material 4 and the air. Since the reflection of the ultrasonic wave at the boundary can be suppressed and the propagation efficiency of the ultrasonic wave can be increased, there is an effect that the sensitivity of the air ultrasonic sensor 2 is improved and the detection distance can be expanded.

  Further, according to the third embodiment of the present invention, since the resin material 4 is formed of the same material as that of the mounting portion 1, when painted, it is more difficult to produce a difference in color development, and visibility from the outside is improved. Can be reduced.

  Further, according to the third embodiment of the present invention, as in the first and second embodiments of the present invention, when the aerial ultrasonic sensor of the obstacle detection device is attached to the bumper portion of the vehicle, radiation is performed. Since the surface is not exposed to the outside or dented by the horn, the bumper part of the vehicle is easy to maintain, the deterioration of the detection performance of the airborne ultrasonic sensor can be suppressed, and the appearance of the mounting part ( Designability) can be improved.

Embodiment 4 FIG.
Next, in the obstacle detection device according to the fourth embodiment of the present invention, by setting the length L of the horn 3 and the resin material 4 with respect to the wavelength λ of the ultrasonic wave, the acoustic impedance of the aerial ultrasonic sensor 2 and An obstacle detection device that matches the acoustic impedance of air will be described.

  FIG. 5 is a schematic diagram showing an example of a cross section of an obstacle detection device according to Embodiment 4 of the present invention. Since the basic configuration and operation of the obstacle detection device according to the fourth embodiment are the same as those of the obstacle detection device according to the first, second, and third embodiments, only different parts will be described. To do.

  In the obstacle detection device according to Embodiment 4, when the wavelength of the ultrasonic wave that is excited by the airborne ultrasonic sensor 2 and propagates through the resin material 4 is λ, the length of the horn 3 and the resin material 4 is L. Then, it is comprised so that L may become Formula (3). Here, n is an integer represented by 0, 1, 2,.

  With this configuration, it is possible to increase the propagation efficiency of ultrasonic waves, improve the sensitivity of the aerial ultrasonic sensor 2 and increase the detection distance.

  As described above, according to the fourth embodiment of the present invention, as in the first embodiment of the present invention, the horn 3 and the resin material 4 are exposed from the through hole of the bumper mounting portion 1 for mounting the obstacle detection device. Thus, since the aerial ultrasonic sensor 2 is attached, the detection distance of the aerial ultrasonic sensor of the obstacle detection device can be increased.

  Further, according to the fourth embodiment of the present invention, the length L of the horn 3 and the resin material 4 is set as shown in the equation (3), so that the ultrasonic wave propagation is suppressed and the ultrasonic wave propagation efficiency is increased. Therefore, the sensitivity of the aerial ultrasonic sensor 2 is improved and the detection distance can be expanded.

  Further, according to the fourth embodiment of the present invention, as in the first, second and third embodiments of the present invention, the aerial ultrasonic sensor of the obstacle detection device is attached to the bumper portion of the vehicle. The radiating surface is not exposed to the outside or the horn is not recessed, so that the vehicle bumper is easier to maintain, and the deterioration of the detection performance of the aerial ultrasonic sensor can be suppressed. The appearance (designability) of the mounting part can be improved.

  In the embodiment of the present invention, the example in which the obstacle detection device is attached to the bumper of the vehicle and the obstacle around the vehicle is detected has been described. However, the obstacle detection is not limited to the vehicle but is detected from various moving objects. Needless to say, you can. In addition, this obstacle detection device can be fixedly installed and used for detecting or observing the movement of an object based on a change in the distance to the obstacle.

  DESCRIPTION OF SYMBOLS 1 Attachment part, 2 aerial ultrasonic sensor, 3 horn, 4 resin material, 11 through-hole, 21 case, 22 piezoelectric ceramic, 23 lead wire, 41 hollow microcapsule.

Claims (5)

An obstacle detection device comprising a mounting portion provided with a through hole and an aerial ultrasonic sensor fixed to the through hole of the mounting portion,
The aerial ultrasonic sensor is configured such that an opening of the horn is fixed to the rear of the through hole of the attachment portion via a horn disposed in front, and a resin material is included inside including at least the opening of the horn. Obstacle detection device filled. When the acoustic impedance of air is Za, the acoustic impedance of the airborne ultrasonic sensor is Zs, and the acoustic impedance of the resin material is Zm, these three acoustic impedances are:

The obstacle detection device according to claim 1, wherein the following relationship is satisfied. When the acoustic impedance of air is Za, the acoustic impedance of the airborne ultrasonic sensor is Zs, and the acoustic impedance of the resin material is Zm, these three acoustic impedances are:

The obstacle detection device according to claim 1, wherein the following relationship is satisfied.   The obstacle detection device according to any one of claims 1 to 3, wherein hollow microcapsules are added to the resin material. When the length of the horn and the resin material is L, and the wavelength of the ultrasonic wave propagating through the resin material is λ, n is 0 or a positive integer.

The obstacle detection device according to claim 1, wherein the following relationship is satisfied.

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