JP5592079B2 - Ultrasonic transceiver - Google Patents

Description

The present invention relates to an ultrasonic transmitter / receiver capable of generating ultrasonic waves by vibration of a vibrating surface of a bottomed cylindrical case and receiving ultrasonic waves from the outside on the same surface.

2. Description of the Related Art Conventionally, ultrasonic transmitters / receivers that can generate ultrasonic waves by vibration of a vibration surface and can receive ultrasonic waves from the outside on the same surface have been widely used. 2. Description of the Related Art In recent years, ultrasonic transmitters / receivers made of a structure in which a piezoelectric element is attached to the bottom of a bottomed case made of metal have been produced in large quantities for back sonar of automobiles (vehicles). Since these ultrasonic transmitters / receivers generate ultrasonic waves in the air by vibration of the ultrasonic transmitters / receivers, when these ultrasonic transmitters / receivers are installed, they are made of a soft material that does not interfere with the vibrations of the ultrasonic transmitter / receiver. Need to hold sonic transceiver. Moreover, in order to prevent the noise which arises when the vibration of an ultrasonic transmitter / receiver is transmitted to the object which attaches an ultrasonic transmitter / receiver, it is necessary to hold | maintain an ultrasonic transmitter / receiver with a material with high vibration insulation. In order to hold the ultrasonic transceiver, a cushion made of a low hardness silicone material is often used.

Ultrasonic transceivers that do not require cushions are also being developed. For example, there is an ultrasonic transmitter / receiver having a double-side structure by adding grooves to the side surface of a bottomed cylindrical case constituting the ultrasonic transmitter / receiver (see Patent Document 1). However, in the ultrasonic transmitter / receiver in which the case itself has a double structure, vibration transmission from the ultrasonic transmitter / receiver to the mounting target is still large, and performance sufficient to satisfy customer requirements is not obtained.
Japanese Patent Publication No. 2004-343660 Tanikoshi Shinji “Ultrasound and how to use it – Ultrasonic Transceiver / Ultrasonic Motor”, Nikkan Kogyo Shimbun

Traditionally, cushions that have been used to hold ultrasonic transceivers are often materials that cannot be painted, and the design surface of the ultrasonic transceiver and the object to be attached to the ultrasonic transceiver, such as the bumper of the vehicle, are the same color. Even if it is painted, the color of the cushion cannot be matched, and thus there are many problems in design. If the cushion material is changed to a resin material that can be painted, such as PP, the vibration insulation will decrease due to an increase in the elastic modulus of the cushion, and the vibration of the ultrasonic transceiver will be transmitted to the housing and bumper. The excessive noise that occurs is a problem. Further, when a hard material is used, the influence on the characteristics of the ultrasonic transmitter / receiver when bonded to the ultrasonic transmitter / receiver is larger than that of the silicone cushion. Problems such as a decrease in resonance frequency and a decrease in sensitivity due to vibration suppression occur.

Therefore, the present invention has a structural feature that can improve vibration insulation and prevent vibration suppression when bonded, and by attaching a cover made of a paintable resin material to the ultrasonic transceiver, The object is to realize an ultrasonic transmitter / receiver that does not require a cushion without impairing the function of the ultrasonic transmitter / receiver.

In the invention described in claim 1, in the ultrasonic transmitter / receiver that generates ultrasonic waves by top surface vibration of the bottomed cylindrical case and receives external ultrasonic waves on the same surface,
A vibration absorber comprising a bottom surface comprising at least two or more stacked cylinders having an inner cylinder and an outer cylinder , wherein at least one end between the innermost cylinder and the outermost cylinder is closed. By mounting, an ultrasonic transmitter / receiver that does not require a cushion between the mounting portion of the ultrasonic transmitter / receiver while preventing the function of the ultrasonic transmitter / receiver from being deteriorated is realized.

The invention according to claim 2 is characterized in that one end of the innermost cylinder of the vibration absorber is also closed and has a bottom surface. The design of the ultrasonic transmitter / receiver is covered with a vibration absorber, thereby realizing an ultrasonic transmitter / receiver with dramatically improved sealing performance and paintability.

In the invention described in claim 3, a step is provided on the bottom surface of the vibration absorber described in claim 2, and the bottom surface thickness of the portion where the top surface of the bottomed cylindrical case is bonded is made thinner than the other portions. Thus, a highly sensitive ultrasonic transmitter / receiver is realized without reducing the strength of the vibration absorber. The thickness of the portion where the bottomed cylindrical case is bonded must be as thin as possible in order to reduce the sensitivity of the ultrasonic transceiver as the thickness increases. However, when the entire bottom surface is thinned, the strength of the vibration absorber is greatly reduced. By providing the step, both strength and performance can be achieved.

Practical example 1

FIG. 2-a shows an embodiment of the present invention. For example, a circular piezoelectric element 2 made of lead zirconate titanate (PZT) in which silver electrodes independent on both surfaces 2a are provided on the bottom surface 1b of an aluminum case 1 having a φ12 circle as a design surface 1a and a height of 9 mm. A bottomed vibration absorber 4 having an outer diameter φ16, an inner diameter φ12, and a height of 9 mm is bonded to an ultrasonic transmitter / receiver 3 having a bonded structure. The dimensions inside the aluminum case and the dimensions of the PZT are designed so that the resonance frequency is 68 kHz. The vibration absorber 4 consists of two concentric cylinders, and the thickness of the outer cylinder 4a and the inner cylinder 4b is 0.5 mm. The outer cylinder 4a and the inner cylinder 4b are completely connected by a bottom surface having a thickness of 0.5 mm. The vibration absorber 4 is formed of a resin material having a soft elastic modulus equivalent to ABS in order to enhance vibration insulation. On the outer periphery of the vibration absorber 4, ribs for positioning are provided. A space between the outer cylinder 4 a and the inner cylinder 4 b of the vibration absorber 4 is filled with silicone 5 having a hardness of about 40. In addition to silicone, internal reverberation can be suppressed by filling urethane, low-hardness elastomer, and rubber. The side surfaces of the ultrasonic transmitter / receiver 3 and the vibration absorber 4 are bonded with an adhesive so that there is no step between the design surface 1 a of the ultrasonic transmitter / receiver 3 and the design surface 4 c of the vibration absorber 4. The design surface 1a of the ultrasonic transceiver 3 and the design surface 4a of the vibration absorber 4 are painted in the same color. The ultrasonic transmitter / receiver 3 to which the vibration absorber 4 is bonded is fitted into a housing 6 having attachment portions having an outer diameter φ18 and an inner diameter φ16. Further, this is attached to a resin bumper cover 9 attached to a bumper 7 made of a resin material via a metal spring 8.

For comparison, FIG. 2B shows a state of an ultrasonic transmission / reception apparatus in which an ultrasonic transmission / reception apparatus is assembled using a cushion 13 which is a conventional method. In the conventional method, since the color of the cushion 13 is different from the colors of the ultrasonic transceiver 3, the bumper cover 9, and the bumper 7, there is a problem that the design is poor. On the other hand, in the ultrasonic transmission / reception apparatus embodying the present invention, the design surface 4a of the vibration absorber 4 is painted in the same color as the ultrasonic transmission / reception unit 3, the bumper cover 9, and the bumper 7, so The cushion does not stand out and the design is improved.

Next, reflection sensitivity and reverberation characteristics in a state where the vibration absorber 4 of the present invention is attached will be shown. The sensitivity / reverberation measurement of the ultrasonic transmitter / receiver 3 was performed with the ultrasonic transmitter / receiver 3 bonded with the vibration absorber 4 of the present invention attached to the bumper 7. For comparison, the results when the vibration absorber 4 of the present invention is replaced with a pipe-shaped cover 14 having an outer diameter φ16 and an inner diameter φ12 are also shown. The cover 14 and the ultrasonic transceiver 3 are bonded. The vibration absorber 4 and the cover 14 are made of the same ABS equivalent resin. FIG. 3 shows waveforms of reflection sensitivity and reverberation when the ultrasonic transmission / reception apparatus is driven at 68 kHz. 3A shows a waveform when the cover 14 is used, and FIG. 3B shows a waveform when the vibration absorber 4 of the present invention is used. Compared with the apparatus using the cover 14, the apparatus using the vibration absorber 4 of the present invention has high reflection sensitivity, short reverberation, and no extra noise. Comparing the reflection waveform when the vibration absorber 4 of the present invention and the cover 14 are used, the reflection waveform of the cover 14 is reduced to almost half as compared with the reflection waveform of the vibration absorber 4. Since the influence of the cover 4 on the ultrasonic transceiver 3 is large, the reflected waveform is small. On the other hand, when the vibration absorber 4 of the present invention is attached, the reflection waveform from the pole installed 60 cm ahead of the ultrasonic transmitter / receiver is clearly observed because of less influence by adhesion.

FIG. 4 shows a modified view of the vibration absorber 4 and the cover 14 calculated by the finite element method. 2 shows the result of frequency response analysis when the displacement amount of one end 6b of the housing 6 described in FIG. 2 is fixed to 0 and a potential difference of 68 kHz is applied to the electrode surface 2a of the piezoelectric element 2 as a load. The result of using the cover 14 is shown in FIG. 4-a, and the result of using the vibration absorber 4 of the present invention is shown in FIG. 4-b. In the cover 14, the deformation inside the cover caused by the deformation of the ultrasonic transmitter / receiver 3 is transmitted to the outside of the cover. On the other hand, in the vibration absorber 4 of the present invention, the cylindrical portion 4b and the bottom surface inside the vibration absorber are greatly deformed by the deformation of the ultrasonic transmitter / receiver 3, but the change of the cylindrical portion 4a outside the vibration absorber is suppressed. . As described above, the shape of the vibration absorber 4 according to the present invention allows the inner cylinder 4b and the bottom surface to be easily deformed so that the vibration of the ultrasonic transmitter / receiver 3 is not hindered and the vibration absorber 4 is bonded. Sensitivity degradation can be prevented. Further, this shape characteristic makes it difficult to transmit the deformation generated in the ultrasonic transceiver 3 to the outer housing 6. By painting the vibration absorber 4 on the ultrasonic transmitter / receiver 3, the bumper cover 9, and the bumper 7 in the same color, the design can be improved.

Practical example 2

Next, an embodiment of the invention of claim 2 is shown in FIG. The vibration absorber 4 in the previous embodiment is replaced with the vibration absorber 15 in which the innermost cylinder is provided with a thin bottom 15a. The thickness of the bottom surface provided in the innermost cylinder is 0.3 mm. Other dimensions are the same as those in the first embodiment. The vibration absorber 15 is formed of a resin material having a soft elastic modulus equivalent to ABS. The design surface of the ultrasonic transceiver 3 is bonded to the bottom surface of the innermost cylinder provided in the vibration absorber 15 with an adhesive. The inside of the vibration absorber 15 is filled with silicone 5 having a hardness of about 40. The design surface 15a of the vibration absorber 15 has the bumper cover 9 and the bumper 7 painted in the same color.

The shape characteristic of the vibration absorber 15 of the present invention reduces the sensitivity due to adhesion of the vibration absorber 15 without disturbing the vibration of the ultrasonic transceiver 3 by easily deforming the inner cylinder 4b and the bottom surface. Can be prevented. Further, this shape characteristic makes it difficult to transmit the deformation generated in the ultrasonic transceiver 3 to the outer housing 6. Although the reflection sensitivity is slightly lower than in the previous embodiment using the vibration absorber 4, the sealing property and the paintability are improved by completely covering the design surface.

An example of an ultrasonic transceiver according to the present invention and a cover of the present invention Embodiment of the present invention and conventional ultrasonic transmission / reception apparatus Reflection sensitivity and reverberation waveform Analysis result by finite element method An example of an ultrasonic transmission / reception apparatus according to claim 2 An example of an ultrasonic transmission / reception apparatus according to claim 5

1 Aluminum case 1a Aluminum case top (design side)
1b Aluminum case bottom 2 PZT
2a PZT both sides (silver electrode part)
DESCRIPTION OF SYMBOLS 3 Ultrasonic transmitter / receiver 4 Vibration absorber which implemented this invention of Claim 1 4a Outermost cylinder 4b Innermost cylinder 5 Silicone 6 Housing 7 Bumper 8 Metal spring 9 Bumper cover 10 Sound absorbing material 11 Sealant 12 Lead Wire (electrode)
13 Cushion 14 Pipe-shaped cover installed for comparison 15 Vibration absorber implementing the present invention according to claim 3 16 Vibration absorber implementing the present invention according to claim 5

Claims (3)

In an ultrasonic transmitter / receiver that generates ultrasonic waves by top surface vibration of a bottomed cylindrical case and receives ultrasonic waves from the outside on the same surface,
On the side of the bottomed cylindrical case,
It is composed of at least two or more stacked cylinders having an inner cylinder and an outer cylinder made of a resin material, and at least one end between the innermost cylinder and the outermost cylinder is closed and has a bottom surface. An ultrasonic transmitter / receiver characterized in that a vibration absorber is attached. The ultrasonic transceiver according to claim 1, wherein one end of the innermost tube of the vibration absorber is also closed and has a bottom surface. The bottom surface of the innermost tube of the vibration absorber and the bottom surface of the ultrasonic transceiver are bonded,
A step is provided on the bottom surface of the vibration absorber, and the bottom thickness of the portion where the top surface of the bottomed cylindrical case is bonded,
The ultrasonic transceiver according to claim 2, wherein the ultrasonic transceiver is thinner than other portions.

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