JP4075733B2 - Ultrasonic sensor - Google Patents

Ultrasonic sensor Download PDF

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Publication number
JP4075733B2
JP4075733B2 JP2003297452A JP2003297452A JP4075733B2 JP 4075733 B2 JP4075733 B2 JP 4075733B2 JP 2003297452 A JP2003297452 A JP 2003297452A JP 2003297452 A JP2003297452 A JP 2003297452A JP 4075733 B2 JP4075733 B2 JP 4075733B2
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side wall
2c
cylindrical side
bottom surface
2b
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JP2005072771A (en
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善久 佐藤
博之 可児
清成 小田
久永 松岡
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株式会社デンソー
株式会社日本自動車部品総合研究所
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Description

  The present invention relates to an ultrasonic sensor that is mounted on a vehicle such as an automobile and detects that there is a possibility of contacting an obstacle during parking or turning.

Conventionally, an ultrasonic sensor has been used as a vehicle obstacle detection device. For example, an ultrasonic transducer with a piezoelectric vibration element attached to the bottom of a cylindrical housing is installed in the vehicle's bumper, and the ultrasonic transducer transmits ultrasonic waves from the rear or corner of the vehicle, The obstacle is detected by receiving the ultrasonic wave reflected by the object with an ultrasonic transducer (see, for example, Patent Document 1).
JP 2001-16694 A

  FIG. 11B shows an example of an ultrasonic transducer created by the present inventors. The ultrasonic transducer shown in FIG. 11B includes a double cylindrical portion of an inner side wall 2a and an outer side wall 2b, and a bottom surface portion 2c that is located on one end side of the cylindrical portion and serves as an ultrasonic radiation surface. And a housing 2 made of aluminum or the like. The inner side wall 2a and the bottom surface portion 2c constitute an inner housing, and the piezoelectric vibration element 1 is mounted on the inner surface of the inner housing of the bottom surface portion 2c of the inner housing. Note that the inside of the inner casing means a hollow portion formed by the inner side wall 2a and the bottom surface portion 2c. Further, the outer side wall 2b and the bottom surface portion 2c constitute an outer casing.

  Of the two lead wires 6, one lead wire 6a is connected to the non-mounting surface 1a of the piezoelectric vibration element 1, and the other lead wire 6b is connected to the inner side wall 2a. In this way, the non-mounting surface 1 a and the mounting surface 1 b of the piezoelectric vibration element 1 are electrically connected to the lead wire 6. In addition, the sound absorbing material 3 is disposed on the bottom surface portion 2c side in the inside of the inner housing, and further, the inside of the housing 2 including the inside of the inner housing is filled with the filler 4.

  In the ultrasonic transducer having such a structure, as shown in FIG. 11A, of the bottom surface portion 2c, the connection portion 10 with the inner side wall 2a is a node, and the radial center of the bottom surface portion 2c is an antinode. Vibrate. Further, in the bottom surface portion 2c, the connection portion 10 with the inner side wall 2a and the connection portion 11 with the outer side wall 2b are used as nodes, and the region 2d between the connection portion 10 and the connection portion 11 in the bottom surface portion 2c. Will vibrate. The vibration in the region 2d between the connection portion 10 and the connection portion 11 of the bottom surface portion 2c has an opposite phase to the vibration at the center of the bottom surface portion 2c.

  As a result, the vibration at the outermost peripheral portion of the bottom surface portion 2c (in the vicinity of the connection portion 11 between the bottom surface portion 2c and the outer side wall 2b) is reduced as compared with an ultrasonic transducer having a structure in which the housing 2 is not double. can do. As a result, this ultrasonic transducer can suppress the propagation of ultrasonic waves in a direction parallel to the bottom surface portion 2c.

  However, in general, when there is a portion that vibrates in the opposite phase with respect to the vibration at the center of the ultrasonic radiation surface 2c, compared to the case where there is no portion that vibrates in the opposite phase, from the ultrasonic radiation surface. It is known that the directivity of the emitted ultrasonic energy, that is, the radiation spread angle is wide. When the directivity in the vertical direction, particularly the lower side (ground direction) than the ultrasonic transducer, is wide, since the unevenness of the ground is detected, there is a demand for narrowing the directivity in the ground direction. This is more demanding as an obstacle located far from the vehicle is detected.

  Therefore, as a method of narrowing the directivity in the ground direction with respect to the ultrasonic transducer having the above-described structure, a method of increasing the rigidity of the outer peripheral side wall by increasing the thickness of the outer peripheral side wall 2b is considered for the following reason. It is done. When the whole outer peripheral side wall 2b is thin, when the ultrasonic radiation surface 2c is vibrated by the piezoelectric vibration element 1, the outer side wall 2b itself moves, so that the outermost peripheral portion of the bottom surface portion 2c vibrates. In general, it is known that the greater the vibration at the outermost periphery of the bottom surface 2c, the wider the directivity. Therefore, by increasing the thickness of the outer peripheral side wall, it is possible to reduce the vibration at the outermost peripheral portion of the bottom surface portion 2c due to the deflection of the outer peripheral side wall, and to narrow the directivity in the ground direction.

  However, when aluminum or the like is used as the material of the housing 2, if the outer peripheral side wall 2 b is made thicker, the volume of the outer side wall 2 b increases, so that the attenuation of vibration is delayed inside the outer peripheral side wall itself, and the reverberation time is extended. The problem occurs. Since the ultrasonic transducer performs the detection of the ultrasonic wave and the reflected wave in the same part, if the vibration remains on the ultrasonic wave emission surface after detecting the ultrasonic wave, the ultrasonic wave reflected on the obstacle is detected. I can't. For this reason, if the reverberation time is extended, only obstacles located at a long distance from the vehicle can be detected, and obstacles located at a short distance from the vehicle cannot be detected.

  As other methods, a method of increasing the frequency of the oscillating ultrasonic wave or increasing the area of the ultrasonic radiation surface can be considered. However, when using an ultrasonic sensor as a vehicle obstacle detection device, there is a limit to the frequency of ultrasonic waves that can be used, and the higher the frequency, the easier it is to attenuate in the air. The problem of not returning will occur. In addition, since the ultrasonic transducer for a vehicle is usually installed on a bumper, the size of the ultrasonic radiation surface is limited. For this reason, in these methods, the directivity may not be sufficiently narrowed. Therefore, it is preferable to narrow the directivity without using a method of changing the size of the ultrasonic radiation surface or the ultrasonic vibration frequency.

  The above-described problem is not limited to the case where the tube portion is double, but similarly occurs even when the tube portion is triple or more.

  In view of the above-described points, an object of the present invention is to narrow the directivity in the ground direction while suppressing the attenuation of internal vibration of the outermost peripheral side wall itself in a housing having a plurality of cylindrical portions.

  In order to achieve the above object, in the first aspect of the present invention, the second cylindrical side wall (2b) is provided with convex portions (2e, 2f) projecting toward the outside of the housing (2). It is characterized by being.

  Thereby, compared with the case where the convex part is not provided in the 2nd cylindrical side wall, when a bottom face part is vibrated with a piezoelectric vibration element, it can suppress that a 2nd cylindrical side wall moves. . For this reason, compared with the case where the convex part is not provided in the 2nd cylindrical side wall, it can control that the outermost peripheral part of a bottom part vibrates in conjunction with the 2nd cylindrical side wall, The directivity in the ground direction can be narrowed.

  According to the first aspect of the present invention, since only a part of the second cylindrical side wall is thicker than the other part, the second cylindrical side wall is vibrated when the bottom surface portion is vibrated by the piezoelectric vibration element. As compared with a case where all of the above are made thicker, it is possible to suppress the delay of the attenuation of the internal vibration in the second cylindrical side wall itself.

  In addition, the shape of a convex part can also be made into the shape which was discontinuous in the perimeter of a 2nd cylindrical side wall, or a continuous shape as shown in Claim 2.

  Moreover, as shown in Claim 3, it is preferable that the position of the convex part (2e) is on the extended line of the bottom part. In the invention according to claim 3, the rigidity of the outermost peripheral portion of the bottom surface portion can be increased as compared with the case where the convex portion is not provided on the second cylindrical side wall. For this reason, the vibration in this part can be suppressed compared with the case where the 2nd cylindrical side wall is not provided with the convex part. As a result, the directivity in the ground direction can be reduced.

  Moreover, as shown in Claim 4, among 2nd cylindrical side walls (2b), the 1st site | part (2e) located on the extended line of a bottom face part (2c), and the 1st site | part away from the 1st site | part It is more preferable to provide convex portions at the second portion (2f).

  In the invention according to claim 4, the rigidity of the outermost peripheral portion of the bottom surface portion can be increased as compared with the case where the convex portion is not provided on the second cylindrical side wall. It is possible to suppress the movement of the second cylindrical side wall when the bottom surface portion is vibrated. For this reason, compared with the case where the convex part of the second cylindrical side wall is provided only in the first part or only in the second part, the vibration in the outermost peripheral direction of the bottom surface part is further increased. Can be suppressed. As a result, the directivity in the ground direction can be narrowed.

  Moreover, in this invention, the volume of the 2nd cylindrical side wall is small compared with the case where one convex part is formed from the 1st site | part to the 2nd site | part. Thereby, the internal vibration in the 2nd cylindrical side wall can be attenuate | damped faster than the case where one convex part is formed from the 1st site | part to the 2nd site | part.

  In the invention according to claim 5, the shape of the convex part (2e, 2f) when the casing (2) is viewed from a direction perpendicular to the bottom part (2c) passes through the center of the bottom part (2c). It is characterized by being asymmetric about a straight line.

  As a result, the vibration mode of the ultrasonic wave radiated from the bottom surface becomes asymmetrical, and a region having a wide directivity and a region having a narrow side with respect to the axis passing through the center of the bottom surface can be present. Therefore, by mounting the ultrasonic sensor on the vehicle so that the shape of the convex portion is asymmetric in the top-and-bottom direction and the region of the bottom portion having the narrow directivity is directed downward, the ultrasonic sensor is mounted on the vehicle. As compared with the inventions described in -4, the directivity in the ground direction can be made narrower.

  In the invention according to claim 6, when the housing (2) is viewed in a direction perpendicular to the bottom surface portion (2c), the shape of the second cylindrical side wall (2b) is centered on the bottom surface portion (2c). It is characterized by being asymmetric with a straight line passing through as an axis.

  As a result, the vibration mode of the ultrasonic wave radiated from the bottom surface becomes asymmetrical, and a region having a wide directivity and a region having a narrow side with respect to the axis passing through the center of the bottom surface can be present. For example, the shape of the second cylindrical side wall can be made asymmetric by providing a cutout, a hole, a dent, and a convex portion on the second side wall. In this case, the area on the side where the notch or the like is provided with the axis passing through the center of the housing as the boundary is narrower than the area on the opposite side. As a result, the area on the side provided with the notch or the like is mounted on the vehicle so that the second cylindrical side wall is not provided with a notch or the like. Can be narrowed.

  The invention according to claim 7 is characterized in that the opening of the inner casing is closed by the second sound absorbing material (3b).

  Thereby, compared with the case where the opening part of an inner housing | casing is not obstruct | occluded with the sound absorption material, it can suppress that an ultrasonic wave is discharge | released in the opposite direction to a detection direction.

  The invention according to claim 8 is characterized in that a third sound absorbing material (3c) is disposed between the inner casing and the outer side wall.

  Thereby, compared with the case where the sound-absorbing material is not arranged between the inner casing and the outer casing, it is possible to suppress the emission of ultrasonic waves in the direction opposite to the detection direction.

  In addition, the code | symbol in the bracket | parenthesis of each said means shows the correspondence with the specific means as described in embodiment mentioned later.

(First embodiment)
In the present embodiment, a back sonar or corner sonar for an automobile will be described as an example. FIG. 1 shows an ultrasonic transducer in this embodiment attached to a vehicle, and FIGS. 2 (a) and 2 (b) show the appearance of the ultrasonic transducer in FIG. FIG. 2 (b) is a view taken along the arrow A of the ultrasonic transducer shown in FIG. 2 (a), and FIG. 1 is a cross-sectional view of the ultrasonic transducer shown in FIG. A cross section is shown. Note that, in the ultrasonic transducer shown in FIG. 1, the same reference numerals are given to the same structural parts as those of the ultrasonic transducer shown in FIG.

  In the ultrasonic transducer of the present embodiment, the sound absorbing material 3b is disposed in the shape of the outer side wall 2b and the opening of the inner housing 2a, and the sound absorbing material 3c is disposed between the inner housing 2a and the outer side wall 2b. This is different from the ultrasonic transducer shown in FIG.

  Specifically, as shown in FIG. 1, the housing 2 includes an inner side wall (inner housing) 2a as a first cylindrical side wall and an outer side wall (outer housing) as a second cylindrical side wall. 2b and the bottom face part 2c. The outer side wall 2b is integrally formed with the bottom surface portion 2c, and is disposed coaxially outside the inner side wall 2a via the groove portion 2d. Further, the outer side wall 2 b is located on the outermost periphery of the housing 2.

  As shown in FIGS. 1, 2A, and 2B, the outer side surface of the outer side wall 2b faces the outer side of the housing 2 on the first portion located on the extended line of the bottom surface. The first convex portion 2e protruding in a manner is formed integrally with the outer side wall 2b. Furthermore, the second convex portion 2f is formed integrally with the outer side wall 2b on the outer peripheral side surface of the outer side wall 2b at the second portion away from the first convex portion 2e.

  The 1st convex part 2e becomes what is called a flange shape which continued to the perimeter (circumferential direction) of the outer side wall 2b with the predetermined width 8a. The height of the first convex portion 2e is substantially constant, that is, the thickness of the outer side wall 2b in the portion where the first convex portion 2e is formed is substantially constant. Moreover, the shape of the bottom face part 2c including the 1st convex part 2e is a substantially circular shape, as shown in FIG.2 (b).

  The second protrusion 2f is formed near the center in the direction perpendicular to the bottom surface of the outer side wall 2b. The second convex portion 2f also has a predetermined width 8b and a continuous shape on the entire circumference of the outer side wall 2b, and the thickness of the outer side wall 2b in the portion where the second convex portion 2f is formed is constant. It has become. In this embodiment, the diameter 9c of the cylindrical outer peripheral side wall 2b, the diameter 9a of the outer side wall 2b at the portion where the first convex portion 2e is formed, and the portion where the second convex portion 2f is formed. The diameter increases in the order of 9b.

  The piezoelectric vibration element 1 is made of a piezoelectric ceramic such as PZT, and is a surface on the side where the inner side wall 2a and the outer side wall 2b of the bottom surface portion 2c are disposed (that is, a surface on the inner side of the housing). And is fixed to a region surrounded by the inner side wall 2a.

  And inside the inner housing | casing 2a, the 1st sound absorbing material 3a, such as silicone and urethane, is arrange | positioned at the bottom face part 2c side, and the filler 4a, such as silicone, is filled into the opening part side of the inner housing | casing 2a. The second sound absorbing material 3b is disposed between the inner housing 2a and the outer housing 2b so as to close the opening of the inner housing 2a. Further, the inside of the outer casing 2b is sealed with a filler 4b such as silicone. The material of the sound absorbing material 3 is not limited to silicone and urethane, and other materials can be used as long as they have a sound absorbing effect such as felt and rubber and are soft.

  Moreover, as shown in FIG. 1, the outer side wall 2b including the second convex portion is covered with a vibration absorber 5 such as silicone. However, the bottom surface portion 2 c is exposed from the vibration absorber 5. The ultrasonic transducer configured as described above is attached to a mounting rib 7a installed in a bumper 7 of the vehicle. Thus, since the housing | casing 2 is attached to the bumper 7 via the vibration absorber 5, it can prevent that a vibration is transmitted to the bumper 7 when the housing | casing 2 vibrates. From the viewpoint of suppressing the propagation of vibration to the bumper 7, it is necessary to cover the second convex portion 2 f with the vibration absorber 5.

  In the present embodiment, the surface exposed from the bumper among the surfaces of the bottom surface portion 2c including the first convex portion is the ultrasonic radiation surface.

  Next, the features of the ultrasonic transducer of this embodiment will be described. In this embodiment, since the 1st convex part 2e is formed in the outer side wall 2b, compared with the ultrasonic transducer shown in FIG. 11, the rigidity of the outermost peripheral part 11 of the ultrasonic radiation surface 2c is made. The vibration at the portion 11 can be reduced. Therefore, the directivity in the vertical (ground) direction can be narrowed, and long-distance obstacle detection is possible.

  Furthermore, since the 2nd convex part 2f is formed in the outer side wall 2b, the 2nd convex part 2f becomes weight and can suppress the vibration of the outer side wall 2b. As a result, since the vibration of the outermost peripheral portion 11 of the ultrasonic radiation surface 2c connected to the outer side wall 2b can be further reduced, the directivity in the vertical direction can be further narrowed.

  In addition, the directivity becomes narrow in this way because the amplitude of vibration in the portion 2d that vibrates in antiphase with respect to the center of the ultrasonic radiation surface 2c is reduced, or the amplitude of vibration in the outermost peripheral portion 11. This is because becomes smaller. Further, in the present embodiment, even if the rigidity of the outer side wall 2b is increased in this way, since there is the groove 2d, the vibration at the bottom surface 2c constituting the internal housing is not affected.

  In the present embodiment, by forming the first convex portion 2e and the second convex portion 2f, only the first portion and the second portion of the outer side wall 2b are made thicker than the other portions. ing. Thereby, for example, the volume of the outer side wall 2b is increased as compared with the case where the entire outer side wall 2b is uniformly thickened so that the entire thickness of the outer side wall 2b is the same as that of the first convex portion 2e. Can be suppressed. As a result, compared with the case where the entire outer side wall 2b is uniformly thickened, the internal vibration in the outer side wall 2b can be quickly attenuated, and the reverberation time can be shortened.

  Further, the second convex portion 2f is formed with a space from the first convex portion 2e. For this reason, the thin part 2g can be made between the convex parts 2e and 2f by dispersing the volume of the outer side wall 2b. As a result, the first convex portion 2e and the second convex portion 2f are formed into a continuous shape, and the outer side wall 2b is compared with the case where the first portion to the second portion are thicker than the other portions. Thus, the internal vibration at the outer side wall 2b can be quickly damped.

  For these reasons, it is possible to suppress the drift of the sensor output and improve the detection accuracy of the obstacle at a short distance.

  In addition, although not shown in figure, only the 1st convex part 2e or only the 2nd convex part 2f can also be provided as a convex part formed in the outer side wall 2b. These also make it possible to narrow the directivity in the ground direction as compared with the ultrasonic transducer shown in FIG. 11 in which no convex portion is formed on the outer side wall 2b.

  For reference, FIG. 3 shows directivity measurement results in the case where no convex portion is formed on the outer side wall 2b and in the case where the first convex portion 2e is formed on the outer side wall 2b. The directivity measurement results when the first convex portion 2e is formed on the outer side wall 2b and when the second convex portion 2f is further formed on the outer side wall 2b are shown. In addition, the figure (a) shows the directivity in the vertical direction, and the figure (b) shows the directivity in the horizontal direction. The oscillation frequency at this time is 40 kHz, the diameter 9c of the outer side wall 2b is 21 mm, the diameter 9a of the first convex portion 2e is 24 mm, and the diameter 9b of the second convex portion 2f is 28 mm.

  From the results shown in FIG. 3, it can be seen that even if only the first convex portion 2e is formed on the outer side wall 2b, the directivity in the straight direction is narrower than that in which the convex portion is not formed. Further, the results shown in FIG. 4 show that the directivity in the vertical direction is further narrowed when the second convex portion 2f is formed on the outer side wall 2b in addition to the first convex portion 2e.

  In the present embodiment, since the second convex portion 2f is formed at a distance from the first convex portion 2e, the contact area between the outer side wall 2b and the vibration absorber 5 can be increased. The vibration absorber 5 can easily absorb the vibration of the side wall 2b. Therefore, the first convex portion 2e has a width that is the same as the sum of the width 8a of the first convex portion 2e and the width 8b of the second convex portion 2f, rather than forming one convex portion. And the second convex portion 2f are preferably formed.

  Further, the ultrasonic transducer shown in FIG. 11 is filled with the sound absorbing material 3 on the bottom surface side of the inner housing 2a. However, the sound absorbing material 3 alone does not sufficiently absorb the ultrasonic wave, and the detection direction. The reverberation time was extended by the ultrasonic wave radiated in the opposite direction and reflected and returned.

  On the other hand, in this embodiment, since the opening of the inner housing 2a is further closed by the sound absorbing material 3b, the ultrasonic wave radiated from the opening of the inner housing 2a in the direction opposite to the detection direction is absorbed. In addition, the reverberation time can be shortened. Further, since the sound absorbing material 3c is further disposed between the inner housing 2a and the outer side wall 2b, it is possible to absorb the ultrasonic wave radiated in the direction opposite to the detection direction and shorten the reverberation time.

  In the present embodiment, the case has been described in which both the first convex portion 2e and the second convex portion 2f are continuous in the entire circumference of the outer side wall 2b. The shape may not be continuous over the entire circumference. In this case, from the viewpoint of increasing the rigidity of the outer side wall 2b as compared with the ultrasonic transducer shown in FIG. 11, the length of the region where the convex portion in the outer circumferential (circumferential) direction of the outer side wall 2b is formed, It is known from the experimental results of the present inventors that the length must be 50% or more of the entire circumference of the outer side wall 2b.

  In the present embodiment, the second convex portion 2f is disposed near the center of the outer side wall 2b. However, the second convex portion 2f is not limited to the central portion, and any portion other than the first convex portion 2e may be disposed. Also good. However, from the viewpoint of not increasing the reverberation time, it is preferable that the reverberation time is disposed closer to the center than the end of the outer side wall 2b (the end opposite to the bottom surface portion 2c). This is because the reverberation time is extended when the filler 4b that seals the outer casing 2b is not positioned to the end of the outer side wall 2b.

  Moreover, it is preferable that the diameter 9a of the 1st convex part 2e and the diameter 9b of the 2nd convex part 2f shall be 2 times or less of the diameter 9c of the outer side housing | casing 2b. According to the experimental results of the present inventors, when the frequency is twice or more, the vibration of the convex portion itself is increased and the reverberation time is extended.

  Further, the width 8a of the first protrusion 2e and the thickness 8b of the second protrusion 2f are 50% or less of the total width 8c of the entire outer side wall 2b, considering reverberation time. It is known from the experimental results of the present inventors that this is good. Similarly, if the total width of the convex portions is 50% or less of the entire width 8c of the outer side wall 2b, three or more convex portions can be formed on the outer side wall 2b.

(Second Embodiment)
FIG. 5 shows a cross-sectional view of the ultrasonic transducer in the second embodiment. Since the same components as those of the ultrasonic transducer shown in FIG. 1 are denoted by the same reference numerals, only the portions different from the first embodiment will be described here.

  In the first embodiment, the outer side wall 2b, the first convex portion 2e, and the second convex portion 2f are integrally formed, whereas in the present embodiment, the outer side wall 2b, the first convex portion 2e, and The 2nd convex part 2f is not integrally molded. The 1st convex part 2e and the 2nd convex part 2f are comprised with the same material (aluminum etc.) as the outer side wall 2b, and these are press-fitted in the outer side wall 2b. As shown in FIG. 5, in this embodiment, the bottom side portion 2 g of the outer side wall 2 b is thickened and the opening side portion 2 h is thin so that these can be easily press-fitted.

  Also in this embodiment, since the 1st convex part 2e and the 2nd convex part 2f are provided in the outer side wall 2b, it has the same effect as 1st Embodiment.

  In addition, the material of the 1st convex part 2e and the 2nd convex part 2f can also be made into the material different from the outer side wall 2b. When the material of the convex portions 2e and 2f is different from that of the outer side wall 2b, it is desirable to use a material having a high density and a large vibration damping effect. For example, iron, stainless steel, lead, vibration damping alloy, etc. Can be used.

  Further, as a method for joining the outer side wall 2b to the first convex portion 2e and the second convex portion 2f, methods such as adhesion, welding, caulking, and screw fastening can be used in addition to press-fitting. Also in the present embodiment, the number of convex portions can be one or three or more as in the first embodiment.

(Third embodiment)
FIG. 6 shows a cross-sectional view of an ultrasonic transducer according to the third embodiment. Since the same components as those of the ultrasonic transducer shown in FIG. 1 are denoted by the same reference numerals, only the portions different from the first embodiment will be described here.

In the present embodiment, a second inner side wall 2i is further provided between the first inner side wall 2a and the outer side wall 2b with respect to the ultrasonic transducer shown in FIG. The first inner casing 2a, the second inner casing 2i, and the outer casing 2b are provided with a triple cylindrical portion. The second inner side wall 2i is also formed integrally with the outer side wall 2b. In the present embodiment, the width in the direction perpendicular to the bottom surface portion of the second inner side wall 2i is smaller than the inner side wall 2a so as to facilitate integral molding.
And the inside of the 2nd inner side housing | casing 2i is filled with the filler 4c.

  Thus, by making the housing | casing 2 into a triple structure, the vibration in the outermost peripheral part of the ultrasonic radiation surface 2c can be made small, As a result, it is further more than the ultrasonic transducer shown in FIG. Directivity can be narrowed. Further, the propagation of vibrations to the bumper can be further suppressed as compared with the ultrasonic transducer shown in FIG.

  In the ultrasonic transducer shown in FIG. 6, the housing 2 has a structure having a triple cylindrical portion, but the cylindrical portion may be triple or more.

(Fourth embodiment)
FIG. 7 shows the appearance of the ultrasonic transducer according to the fourth embodiment and the mounting position of the ultrasonic transducer on the vehicle.

  The ultrasonic transducer shown in FIG. 7 is different from the ultrasonic transducer shown in FIG. 1 in that a notch 12 is provided in the lower region of the second convex portion 2f. Thus, by providing the notch 12 in the second convex portion 2f, when the housing is viewed from a direction perpendicular to the bottom surface portion 2c, it passes through the center 13 of the bottom surface portion 2c and is parallel to the horizontal direction. When the straight line 14 is drawn, the shape of the second convex portion is asymmetric in the vertical direction with the straight line 14 as an axis. In the horizontal direction, the shape of the second convex portion is a symmetrical shape.

  In this embodiment, as shown in FIG. 7, the ultrasonic transducer is attached to the bumper of the vehicle with the notch 12 on the lower side.

  FIG. 8 shows a directivity measurement result in the ultrasonic transducer having the shape shown in FIG. FIGS. 8A and 8B show measurement results of directivity in the vertical direction and the horizontal direction, respectively. In addition, in FIG. 8, the directivity measurement result in the ultrasonic transducer having a shape with no notch is also shown. Moreover, the angle of the horizontal axis of Fig.8 (a) respond | corresponds to the angle shown in FIG.

  In this embodiment, as shown in FIG. 8B, the directivity in the horizontal direction is symmetric in the horizontal direction. For this reason, the detection area in the horizontal direction of the ultrasonic transducer in this embodiment is symmetric with respect to the ultrasonic transducer.

  On the other hand, in the vertical direction, since the notch 12 is provided in the lower part of the second convex portion 2f, the notch 12 is formed with reference to the center 13 of the bottom surface portion 2c as shown in FIG. The directivity in the vertical direction on the provided side is narrower than the directivity on the opposite side. That is, the directivity is asymmetric in the vertical direction.

  Therefore, in this embodiment, since the ultrasonic transducer is attached to the bumper with the narrower detection area (directivity) as the lower side, as shown in FIG. 7, the obstacle detection area (solid line) Can be directed above the detection area (broken line) when no cutout is provided. As a result, it is difficult to be affected by reflections from the ground, curbstones, etc., and long-distance obstacle detection is possible.

  As described above, the directivity is asymmetrical because the vibrations in the groove portion (thin wall portion) 2d connecting the inner housing 2a and the outer housing 2b and the outermost peripheral portion 11 are asymmetrical, and the notch 12 is formed. It is presumed that, on the provided side, the amplitude of vibration in the groove 2d and the outermost peripheral portion 11 is smaller than that on the side where the notch 12 is not provided.

  Further, in the ultrasonic transducer, normally, as indicated by a broken line in FIG. 2B, the vertical length of the bottom surface portion of the inner casing 2a is made longer than the horizontal direction. This is because the directivity becomes narrower as the vibrating part becomes longer. Therefore, when the ultrasonic transducer is attached to the bumper of the vehicle, it is necessary to match the vertical direction and the horizontal direction of the bottom surface portion 2c. However, when there is no mark such as a notch, there is a problem that the mounting direction is difficult to understand.

  On the other hand, in the present embodiment, since the notch 12 is provided on the lower side of the second convex portion 2f, using the notch 12 as a mark, the notch 12 is positioned on the lower side. An ultrasonic transducer may be attached to a vehicle bumper. For this reason, in this embodiment, compared with the case where there is no notch, an ultrasonic transducer can be easily attached to a vehicle.

  Further, in the present embodiment, the case where the second protrusion 2f has the notch 12 has been described as an example. However, as shown in FIG. The shape of the convex portion 2f can be an asymmetric shape.

  For example, as shown in FIG. 9A, the lower portion of the second convex portion 2 f provided on the entire periphery of the outer side wall 2 b can be cut to have a cut portion 14. . Moreover, as shown in FIG.9 (b), among the 2nd convex parts 2f provided in the perimeter of the outer side wall 2b, in the lower part, the width in the direction perpendicular to the bottom face part is reduced, It can also be made the shape which provided the level | step difference 15 in the 2nd convex part 2f. In this way, the second convex portion 2f provided on the entire circumference of the outer side wall 2b is processed, and the shape of the second convex portion 2f is asymmetrical, so that the ultrasonic radiation surface 2c is perpendicular (ground surface). ) Direction vibration mode can be made asymmetrical in the vertical direction. Even in these cases, the ultrasonic transducer may be attached to the bumper with the narrower detection area facing downward.

  Further, in the present embodiment, as illustrated in FIG. 7, the case where the shape of the second protrusion 2f is symmetrical in the horizontal direction has been described, but the second protrusion 2f is similar to the vertical direction. The shape may be asymmetric in the horizontal direction. Accordingly, the horizontal vibration mode can be made asymmetrical in the same manner as the vertical vibration mode, and the detection area can be tilted to the left (or right).

  Moreover, although the case where the shape of the 2nd convex part 2f was made into asymmetric was demonstrated in this embodiment, the shape of the 1st convex part 2e can also be made asymmetrical. However, if the shape of the first convex portion 2e is asymmetric, the appearance may be impaired. Therefore, the shape of the second convex portion 2f is asymmetrical rather than the shape of the first convex portion 2e. Is more preferable.

  In the present embodiment, the case where the first convex portion 2e and the second convex portion 2f are provided has been described, but the number of convex portions is one or three or more as in the first embodiment. can do. In the case where three or more protrusions are provided, at least one protrusion may be asymmetric.

(Fifth embodiment)
FIGS. 10A, 10B, and 10C show first, second, and third examples of the ultrasonic transducer according to the fifth embodiment, respectively. In addition, the figure on the left side shows an external appearance when the ultrasonic transducer is viewed from the lateral direction, and the figure on the right side is a view seen from the arrow B. In these figures, the inner side wall 2a is omitted.

  In the ultrasonic transducer shown in FIG. 10A, only the first convex portion 2e in the ultrasonic transducer shown in FIG. 1 is formed on the outer side wall 2b. The ultrasonic transducer shown in FIG. 10A is provided with a notch 16 at a part of the outer side wall 2b opposite to the end connected to the bottom surface 2c. ing. For this reason, when the housing | casing 2 is seen in the direction perpendicular | vertical with respect to the bottom face part 2c, the shape of the outer side wall 2b is asymmetrical.

  Thus, since the shape of the outer side wall 2b is asymmetric about the straight line passing through the center of the bottom surface portion 2c, the ultrasonic transducer of the first example has a straight line passing through the center of the bottom surface portion 2c. On the axis, the directivity is also asymmetric. For this reason, the area | region in which the notch 16 grade | etc., Is formed in the bottom face part 2c has narrow directivity, and the detection area of an obstruction is narrow.

  Therefore, by attaching the ultrasonic transducer to the bumper of the vehicle with the narrower detection area on the lower side, the outer side wall 2b is not notched, and is perpendicular to the bottom surface. Compared to the case where the shape of the outer side wall 2b is a symmetrical shape, the detection area can be directed upward. As a result, the directivity in the ground direction can be reduced.

  The method of making the shape of the outer side wall 2b asymmetrical is not limited to the above example, and other methods can be used. For example, in the ultrasonic transducer shown in FIG. 10B, a part of the outer side wall 2b opposite to the end connected to the bottom surface 2c is thinner than the other part. . That is, the step 17 is provided at the end of the outer peripheral side wall 2b. In this manner, the shape of the outer side wall 2b when the housing 2 is viewed in a direction perpendicular to the bottom surface portion 2c can be asymmetrical.

  Further, in the ultrasonic transducer shown in FIG. 10C, the outer peripheral side wall 2b is formed with a convex portion 18 protruding outward in the radial direction. In this manner, the shape of the outer side wall 2b when the housing 2 is viewed in a direction perpendicular to the bottom surface portion 2c can be asymmetrical.

  Also, as a mark of the ultrasonic transducer mounting position regardless of directivity, the side wall of the outer housing 2b or the convex portions 2e and 2f may be simply cut out, cut, stepped, convex, etc. it can.

  In the present embodiment, the case where one convex portion 2e is provided on the extended line of the bottom surface portion 2c has been described. However, even in the case where no convex portion is provided on the outer side wall 2b, the same as in the present embodiment. By providing a cutout or the like in the outer side wall 2b, an effect similar to that of the present embodiment is obtained. Moreover, the number of convex parts can also be made into 2 or more similarly to 1st Embodiment.

(Other embodiments)
In each of the above-described embodiments, the case where the inner side wall 2a and the outer side wall 2b are cylindrical has been described as an example. However, the present invention is not limited to the cylindrical shape, and the side walls may have other shapes such as a rectangular tube shape. The present invention can be applied.

It is sectional drawing of the ultrasonic transducer in 1st Embodiment of the state attached to the vehicle. (A) is a side view of an ultrasonic transducer, (b) is an A arrow view of the ultrasonic transducer in (a). It is a figure which shows the measurement result of the directivity of the ultrasonic transducer with which the 1st convex part 2e is formed in the outer side wall 2b. It is a figure which shows the measurement result of the directivity of the ultrasonic transmitter / receiver in which the 1st convex part 2e and the 2nd convex part 2f are formed in the outer side wall 2b. It is sectional drawing of the ultrasonic transducer in 2nd Embodiment. It is sectional drawing of the ultrasonic transducer in 3rd Embodiment. It is a figure which shows the attachment position of the side view of A ultrasonic transducer as a 1st example in 4th Embodiment, A arrow view, and an ultrasonic transducer. It is a figure which shows the directivity measurement result of the ultrasonic transmitter-receiver in 4th Embodiment. It is a side view of the ultrasonic transducer as another example in 4th Embodiment, A arrow line view. It is a side view of the ultrasonic transducer as the 1st-3rd example in a 5th embodiment, and B arrow line view. (B) is sectional drawing of the ultrasonic transducer which the present inventors created, (a) is a conceptual diagram which shows the mode of a vibration when the bottom face part of this ultrasonic transducer is vibrated.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Piezoelectric vibration element, 2 ... Housing | casing, 2a ... Inner side wall (inner housing | casing),
2b ... outer side wall (outer housing), 2c ... bottom surface (ultrasonic radiation surface),
2d ... groove (thin wall), 2e ... first projection, 2f ... second projection,
2i ... second inner side wall (second inner casing), 3 ... sound absorbing material, 4a, 4b ... filler,
5 ... Vibration absorber, 6 ... Lead wire, 7 ... Bumper,
10: a connection part between the bottom part and the inner side wall, 11 ... a connection part between the bottom part and the outer side wall,
12, 16 ... notch, 14 ... cut,
15, 17 ... stepped portion, 18 ... convex portion.

Claims (8)

  1. A first cylindrical side wall (2a), a second cylindrical side wall (2b) located on the outermost periphery, spaced from the first cylindrical side wall (2a), and the first And a housing (2) having a bottom surface portion (2c) disposed on one end side of the second cylindrical side walls (2a, 2b),
    Of the bottom surface portion (2c), a piezoelectric vibration element (1) fixed to an inner surface of the housing (2) and surrounded by the first cylindrical side wall (2a) In an ultrasonic sensor comprising:
    The ultrasonic sensor, wherein the second cylindrical side wall (2b) is provided with convex portions (2e, 2f) protruding toward the outside of the casing (2).
  2. The ultrasonic sensor according to claim 1, wherein the convex portions (2e, 2f) are continuous over the entire circumference of the second cylindrical side wall (2b).
  3. The ultrasonic sensor according to claim 1 or 2, wherein the convex part (2e) is located on an extension line of the bottom part (2c).
  4. The convex portion includes a first portion (2e) located on an extension line of the bottom surface portion (2c) of the second cylindrical side wall (2b) and a second portion separated from the first portion. The ultrasonic sensor according to claim 1, wherein the ultrasonic sensor is provided in the region (2 f).
  5. The shape of the convex part (2e, 2f) when the housing (2) is viewed from a direction perpendicular to the bottom part (2c) is asymmetric with a straight line passing through the center of the bottom part (2c) as an axis. The ultrasonic sensor according to any one of claims 1 to 4, wherein:
  6. A first cylindrical side wall (2a), a second cylindrical side wall (2b) located at the outermost periphery, arranged at a predetermined interval on the outside of the first cylindrical side wall (2a); A housing (2) having a bottom surface portion (2c) disposed on one end side of the first and second cylindrical side walls (2b);
    Of the bottom surface portion (2c), a piezoelectric vibration element (1) fixed to an inner surface of the housing (2) and surrounded by the first cylindrical side wall (2a) In an ultrasonic sensor comprising:
    When the housing (2) is viewed in a direction perpendicular to the bottom surface portion (2c), the shape of the second cylindrical side wall (2b) is about a straight line passing through the center of the bottom surface portion (2c). An ultrasonic sensor characterized by being asymmetric.
  7. The first sound-absorbing material (3a) is disposed in the region on the bottom surface portion (2c) side in the inside of the inner casing constituted by the first cylindrical side wall (2a) and the bottom surface portion (2c). The second sound absorbing material (3b) is disposed in the opening side region of the inner housing, and the opening of the inner housing is blocked by the second sound absorbing material (3b). The ultrasonic sensor according to claim 1, wherein the ultrasonic sensor is provided.
  8. The third sound-absorbing material (3c) is disposed in a region composed of the first cylindrical side wall (2a), the second cylindrical side wall (2b), and the bottom surface portion (2c). The ultrasonic sensor according to any one of 1 to 7.
JP2003297452A 2003-08-21 2003-08-21 Ultrasonic sensor Expired - Fee Related JP4075733B2 (en)

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Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2003297452A JP4075733B2 (en) 2003-08-21 2003-08-21 Ultrasonic sensor

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JP4075733B2 true JP4075733B2 (en) 2008-04-16

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Publication number Priority date Publication date Assignee Title
JP4591302B2 (en) * 2005-10-12 2010-12-01 株式会社デンソー Ultrasonic sensor mounting structure
WO2007102460A1 (en) 2006-03-06 2007-09-13 Murata Manufacturing Co., Ltd. Ultrasonic sensor, and its manufacturing method
JP4835366B2 (en) 2006-10-04 2011-12-14 株式会社デンソー Ultrasonic sensor
JP2009210404A (en) 2008-03-04 2009-09-17 Denso Corp Obstacle detecting system
JP5592079B2 (en) * 2009-04-28 2014-09-17 日本セラミック株式会社 Ultrasonic transceiver
CN102667523A (en) * 2009-12-02 2012-09-12 三菱电机株式会社 Airborne ultrasonic sensor
JP5099175B2 (en) * 2010-05-28 2012-12-12 株式会社村田製作所 Ultrasonic sensor
DE102013022063A1 (en) * 2013-12-23 2015-06-25 Valeo Schalter Und Sensoren Gmbh Method for producing an ultrasonic sensor for a motor vehicle
WO2017141402A1 (en) * 2016-02-18 2017-08-24 三菱電機株式会社 Ultrasonic transmission/reception apparatus, wall member, and method for attaching ultrasonic sensor to wall member

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