JP2010286296A - Mounting structure for ultrasonic transducer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mounting structure for an ultrasonic transducer detecting an existence of a close-range obstacle with immediately converging reverberation vibration propagating from a bumper to a vibrator after ultrasonic transmission. <P>SOLUTION: The ultrasonic transducer detects an existence of an obstacle by receiving a reflected wave of ultrasonic wave emitted from a vibrator 2. The vibrator 2 is attached to a vibrator attachment portion 12, provided at a rear surface 11a of a bumper 11, through an elastic member 14. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an ultrasonic transducer mounting structure, and more particularly to a technique for suppressing the influence of reverberation vibration after ultrasonic transmission.

  As an ultrasonic sensor mounting structure, for example, a case in which a case incorporating a piezoelectric element is directly joined to the back side of a bumper has been proposed (for example, described in Patent Document 1).

JP 2008-145391 A

  However, in the technique described in Patent Document 1, since the vibrator is directly joined to the bumper via the case, the vibration caused by the vibrator when the ultrasonic wave is transmitted is transmitted to the bumper. As a result, the reverberation vibration of the bumper affects the reflected wave from an obstacle present at a short distance, making it difficult to obtain an accurate reflected wave, and the presence of an obstacle at a short distance may not be detected. It was.

  Accordingly, the present invention provides an ultrasonic transducer mounting structure that can converge the reverberation vibration transmitted from the bumper to the vibrator after ultrasonic transmission in a short time and detect the presence of an obstacle at a short distance. To do.

  The ultrasonic transducer mounting structure of the present invention has a structure in which the vibrator is attached to the vibrator mounting portion provided on the back surface of the bumper with an elastic member interposed therebetween.

  According to the mounting structure of the ultrasonic transducer of the present invention, the reverberation vibration remaining in the bumper by ultrasonic transmission can be obtained by mounting the vibrator with the elastic member interposed in the vibrator mounting section provided on the back surface of the bumper. However, it is attenuated by the elastic force of the elastic member and is not easily transmitted to the vibrator. As a result, the reverberation vibration transmitted from the bumper to the vibrator can be converged in a short time, and the reverberation vibration and the reflected wave are mixed by receiving the accurate reflected wave from the obstacle present at a short distance. Thus, it is possible to suppress the possibility of being unable to detect accurately.

FIG. 1 is an enlarged cross-sectional view of an ultrasonic transducer mounting structure according to the first embodiment. FIG. 2 is an enlarged cross-sectional view of an ultrasonic transducer mounting structure according to the second embodiment.

  Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings.

“Embodiment 1”
FIG. 1 is an enlarged cross-sectional view of an ultrasonic transducer mounting structure according to the first embodiment. As shown in FIG. 1, the ultrasonic transducer 1 includes a vibrator 2 that transmits and receives ultrasonic waves, and a case 3 that accommodates the vibrator 2 therein.

  The vibrator 2 includes a piezoelectric element 4, a power supply unit (not shown) for supplying an alternating current to the piezoelectric element 4, a first electrode 5 connected to the piezoelectric element 4, and a first electrode connected to the case 3. The two electrodes 6 are the main components.

  The case 3 is made of a conductive metal material such as aluminum and is formed as a bottomed cylindrical body. In the first embodiment, the cylindrical case 3 is used, but the shape is not particularly limited.

  The piezoelectric element 4 is directly disposed on the bottom inner surface 3 a of the case 3. The piezoelectric element 4 of this embodiment is formed as an element having a circular shape in plan view like the case 3 having a cylindrical shape.

  The first electrode 5 is electrically connected to the piezoelectric element 4 via the first input / output lead 7. The first input / output lead 7 has one end connected to the surface of the piezoelectric element 4 opposite to the contact surface with the case 3 by solder connection, and the other end connected to the end of the first electrode 5 by solder connection. Connected.

  The second electrode 6 is electrically connected to the inner wall surface 3 b of the case 3 via the second input / output lead 8. The second input / output lead 8 has one end connected to the inner wall surface 3b of the case 3 by solder connection, and the other end connected to the end of the second electrode 6 by solder connection. Since the case 3 is made of a conductive metal material, the second electrode 6 is in a state of being electrically connected to the piezoelectric element 4 disposed directly on the bottom inner surface 3 a of the case 3.

  A sound absorbing material 9 made of foamed silicone or the like is disposed on the upper portion of the piezoelectric element 4. In addition, the upper part of the sound absorbing material 9 is filled with a sealant 10 made of silicone or urethane having self-adhesive properties so as to fill the inside of the case 3.

  An ultrasonic transducer 1 configured by housing the vibrator 2 inside a case 3 is attached to a vibrator mounting portion 12 provided on a back surface 11a of a bumper 11 of the vehicle. The vibrator mounting portion 12 is formed as a concave portion 13 in which a part of the bumper 11 is dented toward the surface 11b side, and the case 3 is fixed on the elastic member 14 disposed on the bottom 13a of the concave portion 13. is doing.

  The concave portion 13 is formed as a circular concave portion in which the case 3 is fitted and arranged. The size of the recess 13 is a recess having a circular shape that is slightly larger than the outer dimension of the case 3. The elastic member 14 includes a main body portion 14A disposed on the bottom 13a of the recess 13 and a peripheral wall portion 14B rising from the outer periphery of the main body portion 14A. The main body 14 </ b> A is provided at the bottom of the case 3. The peripheral wall portion 14 </ b> B is provided so as to surround the peripheral wall 3 c in the vicinity of the bottom portion of the case 3. The elastic member 14 is made of, for example, silicon gel, grease, or the like, and attenuates reverberation vibration remaining in the bumper 11 existing on the outer periphery of the main body portion 14A by its own elastic force (note that reverberation vibration is in the vicinity The ultrasonic wave transmitted in advance is controlled so as to be smaller than the vibration generated in the bumper 11 due to the reflected wave reflected from the obstacle existing in (1). In addition, rubber, sponge, or the like can be used for the elastic member 14.

  In the ultrasonic transducer 1 configured as described above, when an alternating current is supplied from the power supply unit between the first electrode 5 and the second electrode 6, the piezoelectric element 4 is mechanically displaced to generate a vibrator. 2 vibrates and ultrasonic waves are emitted. The ultrasonic waves are radiated from the surface 11b side of the bumper 4 toward the front of the vehicle, the rear of the vehicle, or the side of the vehicle. When there is an obstacle around the vehicle, an ultrasonic wave hits the obstacle, and a reflected wave that hits the obstacle is received by the vibrator 2 and vibrates. Then, an electromotive force is generated between the first electrode 5 and the second electrode 6 attached to the piezoelectric element 4. And the presence or absence of an obstruction and the distance from the ultrasonic transducer 1 to an obstruction can be measured by calculating | requiring the magnitude | size of this electromotive force.

  Thus, according to Embodiment 1, since the reverberation vibration of the bumper 11 existing on the outer periphery of the main body portion 14A converges in a short time, the reverberation vibration of the bumper 11 is reflected from an obstacle existing at a short distance. No longer affect. As a result, it is possible to receive an accurate reflected wave from an obstacle present at a short distance, and the presence / absence of the obstacle at a short distance can be accurately confirmed.

  In the first embodiment, the elastic member 14 interposed between the vibrator 2 and the bumper 11 causes variation in processing accuracy on the bonding surface between the vibrator 2 (the bottom surface of the case 3 in this example) and the bumper 11. The generated fine irregularities can be absorbed by the elastic member 11, and the assembling property of the vibrator 2 can be improved by making the adhesive surface uniform.

  In the first embodiment, since the elastic member 14 is provided so as to surround not only the portion corresponding to the bottom of the case 3 but also the peripheral wall 3c in the vicinity of the bottom of the case 3, the case 3 and the bumper 11 are not in direct contact with each other. It has a structure. Therefore, the reverberant vibration of the bumper 11 after ultrasonic transmission can be attenuated by the elastic member 14 and the influence on the vibrator 2 can be suppressed to the maximum.

“Embodiment 2”
FIG. 2 is an enlarged cross-sectional view of an ultrasonic transducer mounting structure according to the second embodiment. In the second embodiment, a part of the bumper 11 is shaved around the case 3 to form the groove 15, and the directivity characteristics of the ultrasonic radiation pattern are variable with the width W and the depth F of the groove 15 as appropriate dimensions. To do.

  Specifically, a part of the bumper 11 is shaved around the case 3 to form a groove 15 that becomes an annular groove. The directivity of the radiation pattern of the ultrasonic wave radiated from the vibrator 2 varies according to the width W and depth F of the groove 15. For example, for the vibrator 2 having a diameter of 14 mm, the directivity of the ultrasonic radiation pattern when the width W of the groove 15 is 2 mm and the depth F of the groove 15 is 2 mm is compared with the case without the groove 15. And a narrow angle of about 50%. In order to obtain a radiation pattern required by the ultrasonic transducer 1, it is obtained by appropriately adjusting the width W and depth F of the groove 15.

  The groove portion 15 is provided with a peripheral wall portion 14B of the elastic member 14 so as to fill the groove portion 15.

  According to the second embodiment, the width of the width 15 and the depth F of the groove 15 obtained by cutting a part of the bumper 11 around the case 3 are appropriately dimensioned, so that the ultrasonic wave emitted from the vibrator 2 is emitted. The directivity of the pattern can be varied, and the ultrasonic transducer 1 having a radiation pattern according to need can be obtained.

  INDUSTRIAL APPLICABILITY The present invention can be used for a structure in which an ultrasonic transducer that detects the presence of an obstacle by receiving a reflected wave reflected by radiating an ultrasonic wave to the obstacle is attached to a vehicle bumper.

DESCRIPTION OF SYMBOLS 1 ... Ultrasonic transducer 2 ... Vibrator 3 ... Case 4 ... Piezoelectric element 5 ... 1st electrode 6 ... 2nd electrode 11 ... Bumper 12 ... Vibrator attaching part 13 ... Recessed part 14 ... Elastic member 15 ... Groove part

Claims (3)

An ultrasonic transducer mounting structure for detecting the presence of an obstacle by receiving a reflected wave reflected by an ultrasonic wave radiated from an oscillator attached to a vehicle bumper,
An ultrasonic transducer mounting structure, wherein the vibrator is attached to a vibrator mounting portion provided on a back surface of the bumper with an elastic member interposed therebetween. An ultrasonic transducer mounting structure according to claim 1,
The vibrator mounting portion is formed as a concave portion in which a part of the bumper is dented toward the surface side, and a case in which the piezoelectric element constituting the vibrator is accommodated is disposed at the bottom of the concave portion. An ultrasonic transducer mounting structure characterized by being fixed on the elastic member. An ultrasonic transducer mounting structure according to claim 2, comprising:
An ultrasonic wave transmission / reception characterized in that a part of the bumper is cut around the case to form a groove part, and the directivity of the ultrasonic radiation pattern is varied by setting the width and depth of the groove part to appropriate dimensions. Waver mounting structure.

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