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JP2005072771

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This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
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DESCRIPTION JP2005072771
PROBLEM TO BE SOLVED: To narrow the directivity in the ground direction while suppressing
that the damping of the internal vibration of the outermost peripheral side wall itself in a casing
having a plurality of cylindrical portions is delayed. SOLUTION: A housing 2 constituted by
having a double cylindrical portion of an inner side wall 2a and an outer side wall 2b, and a
bottom portion 2c located on one end side of this cylindrical portion and serving as an ultrasonic
radiation surface The ultrasonic transmitting and receiving apparatus is provided with an inner
case including the inner side wall 2a and the bottom portion 2c, and the piezoelectric vibrating
element 1 is mounted on the inner side surface of the inner case in the bottom portion 2c of the
inner case. In the wave device, of the outer side wall 2b, the first convex portion 2e is provided
on the extension of the bottom surface portion 2c, and the second convex portion 2f is provided
at a portion distant from the first convex portion 2e. [Selected figure] Figure 1
Ultrasonic sensor
[0001]
The present invention relates to an ultrasonic sensor that is mounted on a vehicle such as a car
and detects, for example, a possibility of coming into contact with an obstacle at the time of
parking or turning.
[0002]
Conventionally, ultrasonic sensors have been used as obstacle detection devices for vehicles.
03-05-2019
1
For example, an ultrasonic transducer having a piezoelectric vibrating element mounted on the
bottom of a cylindrical casing is provided on a vehicle's bumper, and ultrasonic waves are
transmitted from the vehicle rear portion or vehicle corner portion by the ultrasonic transducer.
The obstacle is detected by receiving ultrasonic waves reflected by an object with an ultrasonic
transducer (see, for example, Patent Document 1). Unexamined-Japanese-Patent No. 2001-16694
[0003]
FIG. 11B shows an example of an ultrasonic transducer created by the present inventors. The
ultrasonic transducer shown in FIG. 11 (b) has a double cylindrical portion with an inner side
wall 2a and an outer side wall 2b, and a bottom portion 2c located on one end side of this
cylindrical portion and serving as an ultrasonic radiation surface. The housing 2 is made of
aluminum or the like. The inner casing is constituted by the inner side wall 2a and the bottom
portion 2c, and the piezoelectric vibrating element 1 is mounted on the inner surface of the inner
casing of the bottom portion 2c of the inner casing. The inside of the inner case means a hollow
portion formed by the inner side wall 2a and the bottom portion 2c. Further, the outer side wall
2b and the bottom surface portion 2c constitute an outer casing.
[0004]
Then, one of the two lead wires 6 a is connected to the non-mounting surface 1 a of the
piezoelectric vibration element 1, and the other lead wire 6 b is connected to the inner side wall
2 a. Thus, the non-mounting surface 1 a of the piezoelectric vibration element 1 and the
mounting surface 1 b are electrically connected to the lead wire 6. Further, the sound absorbing
material 3 is disposed on the bottom surface 2c side of the inside of the inner case, and the filling
material 4 is filled in the case 2 including the inside of the inner case.
[0005]
In the ultrasonic transducer having such a structure, as shown in FIG. 11A, in the bottom portion
2c, the connecting portion 10 to the inner side wall 2a is a node, and the radial center of the
bottom portion 2c is an antinode Vibrate. Furthermore, in the bottom surface portion 2c, a region
2d between the connection portion 10 and the connection portion 11 in the bottom surface
03-05-2019
2
portion 2c with the connection portion 10 with the inner side wall 2a and the connection portion
11 with the outer side wall 2b as nodes. Is supposed to vibrate. The vibration in the region 2d
between the connection portion 10 and the connection portion 11 of the bottom surface portion
2c is in opposite phase to the vibration at the center of the bottom surface portion 2c.
[0006]
Thereby, as compared with the ultrasonic transducer having a structure in which the housing 2 is
not doubled, the vibration at the outermost peripheral portion of the bottom portion 2c (near the
connecting portion 11 between the bottom portion 2c and the outer side wall 2b) is reduced. can
do. As a result, this ultrasonic transducer can suppress the propagation of ultrasonic waves in the
direction parallel to the bottom surface 2c.
[0007]
However, in general, when there is a portion that vibrates in antiphase with respect to the
vibration at the center of the ultrasonic radiation surface 2c, compared with the case where there
is no portion that vibrates in antiphase, It is known that the directivity of emitted ultrasonic
energy, that is, the radiation spread angle is wide. When the directivity in the vertical direction,
particularly below the ultrasonic transducer (in the direction of the ground) is wide, unevenness
on the ground is detected, and there is a demand for narrowing the directivity in the direction of
the ground. This is more demanding as it is desirable to detect an obstacle located at a greater
distance from the vehicle.
[0008]
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 thickening all the outer peripheral side walls 2b is considered
for the following reason. Be When the entire outer peripheral side wall 2b is thin, when the
ultrasonic radiation surface 2c is vibrated by the piezoelectric vibrating element 1, the outer side
wall 2b itself moves, and therefore the outermost peripheral portion of the bottom surface
portion 2c vibrates. In general, it is known that the directivity is wider as the vibration at the
outermost peripheral portion of the bottom surface portion 2c is larger. Therefore, by thickening
all the outer peripheral side walls, it is possible to reduce the vibration at the outermost
03-05-2019
3
peripheral portion of the bottom portion 2c due to the bending of the outer peripheral side walls,
and to narrow the directivity in the ground direction.
[0009]
However, when aluminum or the like is used as the material of the housing 2, if all the outer
peripheral side walls 2b are thickened, the volume of the outer side wall 2b is increased, so that
the vibration damping is delayed inside the outer peripheral side wall itself, and the
reverberation time is extended. The problem of Since the ultrasonic transducer performs
detection of the radiation of the ultrasonic wave and the reflected wave in the same part, after
the ultrasonic wave is radiated, if the vibration remains on the ultrasonic radiation surface, the
ultrasonic wave reflected to the obstacle is detected I can not do it. For this reason, when the
reverberation time is extended, only an obstacle located at a long distance from the vehicle can
be detected, and an obstacle located at a short distance from the vehicle can not be detected.
[0010]
As another method, it is conceivable to increase the frequency of oscillating ultrasonic waves or
to increase the area of the ultrasonic radiation surface. However, when an ultrasonic sensor is
used as an obstacle detection device for a vehicle, the frequency of usable ultrasonic waves is
limited, and the higher the frequency, the easier it is to be attenuated in the air. There is a
problem of not returning. Moreover, since the ultrasonic transducer for vehicles is usually
installed in a bumper, the size of the ultrasonic radiation surface is also limited. Therefore, in
these methods, the directivity may not be sufficiently narrowed. Therefore, it is preferable to
narrow the directivity without using the method of changing the size of the ultrasonic radiation
surface or the frequency of ultrasonic waves.
[0011]
In addition, the above-mentioned problem arises not only when a cylinder part is double but
arises similarly even if a cylinder part is triple or more.
[0012]
An object of the present invention is to narrow the directivity in the ground direction while
suppressing the attenuation of the internal vibration of the outermost peripheral side wall itself
in a casing having a plurality of cylindrical portions from being delayed.
03-05-2019
4
[0013]
In order to achieve the above object, in the first aspect of the present invention, the second
cylindrical side wall (2b) is provided with projections (2e, 2f) projecting toward the outside of the
housing (2). It is characterized by
[0014]
Thereby, when the bottom portion is vibrated by the piezoelectric vibrating element, it is possible
to suppress movement of the second cylindrical side wall as compared with the case where the
convex portion is not provided on the second cylindrical side wall. .
For this reason, compared with the case where a convex part is not provided in the 2nd
cylindrical side wall, it can suppress that the outermost peripheral part of a bottom face part
interlockingly moves with the 2nd cylindrical side wall, The directivity in the ground direction
can be narrowed.
[0015]
In the first aspect of the present invention, only a part of the second cylindrical side wall is made
thicker than the other parts, so when the bottom portion is vibrated by the piezoelectric vibration
element, the second cylindrical side wall As compared with the case of thickening all of the
above, it is possible to suppress that the damping of the internal vibration in the second
cylindrical sidewall itself is delayed.
[0016]
In addition, the shape of a convex part can also be made the shape which was discontinuous over
the perimeter of the 2nd cylindrical side wall, or the continuous shape as shown in Claim 2.
[0017]
Preferably, the position of the convex portion (2e) is an extension of the bottom surface portion.
03-05-2019
5
According to the third aspect of the present invention, 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 portion can be suppressed as compared with the case where
the convex portion is not provided on the second cylindrical side wall.
As a result, the directivity in the ground direction can be narrowed.
[0018]
According to a fourth aspect of the present invention, a first portion (2e) of the second cylindrical
side wall (2b) positioned on an extension of the bottom portion (2c) and a first portion (2e)
separated from the first portion It is more preferable to provide a projection on the two parts
(2f).
[0019]
In the invention according to claim 4, the rigidity of the outermost peripheral portion of the
bottom portion can be increased as compared with the case where the convex portion is not
provided on the second cylindrical side wall, and the piezoelectric vibrating element is further
provided. It is possible to suppress movement of the second cylindrical side wall when the
bottom portion is vibrated.
For this reason, compared with the case where the convex portion of the second cylindrical side
wall is provided only at the first portion or only at the second portion, the vibration in the
outermost peripheral direction of the bottom portion is made more It can be suppressed.
As a result, the directivity in the direction of the ground can be narrowed.
[0020]
Further, in the present invention, the volume of the second cylindrical side wall is smaller than in
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6
the case where one convex portion is formed from the first portion to the second portion.
Thereby, internal vibration in the second cylindrical side wall can be damped more quickly than
in the case where one convex portion is formed from the first portion to the second portion.
[0021]
In the invention according to claim 5, the shape of the convex portion (2e, 2f) when the housing
(2) is viewed from the direction perpendicular to the bottom portion (2c) passes through the
center of the bottom portion (2c). It is characterized in that it is asymmetrical about a straight
line.
[0022]
As a result, the vibration mode of the ultrasonic wave emitted from the bottom surface portion
becomes asymmetric, and it is possible to make the side of wide directivity and the region of the
narrow side bordering on the axis passing through the center of the bottom surface.
Therefore, the ultrasonic sensor is mounted on the vehicle by orienting the area of the bottom of
the bottom with a narrow area so that the shape of the convex portion is asymmetrical in the
vertical direction, The directivity in the ground direction can be made narrower than in the
invention described in -4.
[0023]
In the invention according to claim 6, when the housing (2) is viewed in a direction perpendicular
to the bottom surface (2c), the shape of the second cylindrical side wall (2b) is the center of the
bottom surface (2c). It is characterized in that it is asymmetric with the passing straight line as
the axis.
[0024]
As a result, the vibration mode of the ultrasonic wave emitted from the bottom surface portion
becomes asymmetric, and it is possible to make the side of wide directivity and the region of the
narrow side bordering on the axis passing through the center of the bottom surface.
03-05-2019
7
For example, the shape of the second cylindrical side wall can be made asymmetric by providing
a notch, a hole, a recess, or a convex portion in the second side wall. In this case, with the axis
passing through the center of the housing as a boundary, the area on the side provided with the
notch or the like has narrower directivity than the area on the opposite side. As a result, by
mounting the vehicle on the vehicle with the area on the side provided with the notch or the like
facing downward, the direction toward the ground is compared with the case where the notch or
the like is not provided on the second cylindrical side wall You can narrow the sex.
[0025]
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).
[0026]
Thereby, compared with the case where the opening of the inner case is not blocked by the
sound absorbing material, it is possible to suppress the emission of the ultrasonic wave in the
direction opposite to the detection direction.
[0027]
The invention according to claim 8 is characterized in that the third sound absorbing material
(3c) is disposed between the inner casing and the outer side wall.
[0028]
Thereby, compared with the case where no sound absorbing material is disposed 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.
[0029]
In addition, the code | symbol in the parenthesis of each said means shows correspondence with
the specific means as described in embodiment mentioned later.
[0030]
First Embodiment In this embodiment, a back sonar or corner sonar for a car will be described as
an example.
03-05-2019
8
FIG. 1 shows an ultrasonic transducer according to this embodiment in a state of being attached
to a vehicle, and FIGS. 2 (a) and 2 (b) show the external appearance of the ultrasonic transducer
in FIG.
2 (b) is a view on arrow A of the ultrasonic transducer shown in FIG. 2 (a), and FIG. 1 is a
sectional view taken along line B-B of the ultrasonic transducer shown in FIG. The cross section is
shown.
In the ultrasonic transducer shown in FIG. 1, the same parts as those of the ultrasonic transducer
shown in FIG.
[0031]
In the ultrasonic transducer according to this embodiment, the shape of the outer side wall 2b,
the sound absorbing material 3b in the opening of the inner case 2a, and the sound absorbing
material 3c between the inner case 2a and the outer side wall 2b. The point is different from the
ultrasonic transducer shown in FIG.
[0032]
Specifically, as shown in FIG. 1, the housing 2 includes an inner side wall (inner case) 2a as a first
cylindrical side wall and an outer side wall (outer case) as a second cylindrical side wall. It is
comprised by 2b and the bottom face part 2c.
The outer side wall 2b is integrally formed with the bottom portion 2c, and is coaxially disposed
outside the inner side wall 2a via the groove 2d.
The outer side wall 2 b is located at the outermost periphery of the housing 2.
[0033]
03-05-2019
9
Then, as shown in FIGS. 1, 2 (a) and (b), the outer peripheral side surface of the outer side wall 2
b is directed to the outside of the housing 2 at the first portion located on the extension of the
bottom surface portion. A protruding first protrusion 2e is integrally formed with the outer side
wall 2b.
Furthermore, a second convex portion 2f is integrally formed with the outer side wall 2b on a
surface on the outer peripheral side of the outer side wall 2b at a second portion separated from
the first convex portion 2e.
[0034]
The first convex portion 2 e has a so-called flange shape which is continuous with the entire
circumference (circumferential direction) of the outer side wall 2 b with a predetermined width 8
a. 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. Further, as shown in FIG. 2B, the bottom portion 2c including the first convex portion
2e has a substantially circular shape.
[0035]
The second convex portion 2 f is formed near the center in the direction perpendicular to the
bottom surface portion of the outer side wall 2 b. The second convex portion 2f also has a
predetermined width 8b and is continuous to the entire circumference of the outer side wall 2b,
and the thickness of the outer side wall 2b at the portion where the second convex portion 2f is
formed is constant. It has become. In the present 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.
In the order of diameter 9b.
[0036]
The piezoelectric vibrating element 1 is made of piezoelectric ceramic such as PZT, and is a
surface on the side on which the inner side wall 2a and the outer side wall 2b of the bottom
portion 2c are disposed (that is, the surface on the inner side of the housing). It is fixed to the
area surrounded by the inner side wall 2a.
03-05-2019
10
[0037]
The first sound absorbing material 3a such as silicone or urethane is disposed on the bottom
surface 2c side inside the inner case 2a, and the opening 4 side of the inner case 2a is filled with
the filler 4a such as silicone. The second sound absorbing material 3b is disposed to close the
opening of the inner case 2a, and the third sound absorbing material 3c is disposed between the
inner case 2a and the outer case 2b.
Further, the inside of the outer casing 2b is sealed by a filler 4b such as silicone. The material of
the sound absorbing material 3 is not limited to silicone and urethane, and has a sound
absorbing effect such as felt and rubber, and any other material may be used if it is soft.
[0038]
Further, as shown in FIG. 1, the outer side wall 2 b including the second convex portion is
covered by the vibration absorber 5 such as silicone. However, the bottom portion 2 c is exposed
from the vibration absorber 5. And the ultrasonic transducer thus configured is attached to the
mounting rib 7a installed on the bumper 7 of the vehicle. Since the housing 2 is attached to the
bumper 7 via the vibration absorber 5 as described above, it is possible to prevent the
transmission of the vibration to the bumper 7 when the housing 2 vibrates. From the viewpoint
of suppressing the propagation of the vibration to the bumper 7, it is necessary to cover the
second convex portion 2 f with the vibration absorber 5.
[0039]
Further, in the present embodiment, of the surface of the bottom portion 2c including the first
convex portion, the surface exposed from the bumper is the ultrasonic wave emitting surface.
[0040]
Next, features of the ultrasonic transducer according to the present embodiment will be
described.
03-05-2019
11
In the present embodiment, since the first convex portion 2e is formed on the outer side wall 2b,
the rigidity of the outermost peripheral portion 11 of the ultrasonic radiation surface 2c is made
smaller than that of the ultrasonic transducer shown in FIG. It can be made large and the
vibration in this part 11 can be reduced. Therefore, the directivity in the vertical (ground)
direction can be narrowed, and obstacle detection in a long distance becomes possible.
[0041]
Furthermore, since the second convex portion 2f is formed on the outer side wall 2b, the second
convex portion 2f is a weight, and the vibration of the outer side wall 2b can be suppressed. As a
result, 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, and the directivity in the vertical
direction can be further narrowed.
[0042]
The directivity is thus narrowed because the amplitude of the vibration in the portion 2d
vibrating in the opposite phase with respect to the center of the ultrasonic radiation surface 2c
decreases or the amplitude of the vibration in the outermost peripheral portion 11 Is smaller.
Further, in the present embodiment, even if the rigidity of the outer side wall 2b is increased as
described above, since the groove 2d is provided, the vibration at the bottom surface 2c
constituting the inner casing is not affected.
[0043]
Further, 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 to the case where the entire outer side wall 2b is uniformly
thickened so that the entire thickness of the outer side wall 2b is equal to the first convex portion
2e. Can be suppressed. As a result, as compared with the case where the entire outer side wall 2b
is uniformly thickened, internal vibration in the outer side wall 2b can be attenuated quickly, and
the reverberation time can be shortened.
03-05-2019
12
[0044]
Further, a second convex portion 2f is formed at an interval from the first convex portion 2e.
Therefore, the volume of the outer side wall 2b can be dispersed to form the thin portion 2g
between the convex portions 2e and 2f. As a result, the first convex portion 2 e and the second
convex portion 2 f are formed in a continuous shape, and compared with the case where the first
portion to the second portion in the outer side wall 2 b is thicker than the other portions. Thus,
internal vibrations in the outer side wall 2b can be damped quickly.
[0045]
From these facts, it is possible to suppress the drift of the sensor output and to improve the
detection accuracy of an obstacle at a short distance.
[0046]
Although not shown, only the first convex portion 2e or only the second convex portion 2f may
be provided as the convex portion formed on the outer side wall 2b.
Also by these, the directivity in the ground direction can be narrowed as compared with the
ultrasonic transducer shown in FIG. 11 in which the convex portion is not formed on the outer
side wall 2b.
[0047]
Here, as a reference, FIG. 3 shows measurement results of directivity in the case where the
convex portion is not 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 measurement result of the directivity in the
case where the 1st convex part 2e is formed in the outer side wall 2b, and when the 2nd convex
part 2f is further formed in the outer side wall 2b is shown. 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.
03-05-2019
13
[0048]
From the results shown in FIG. 3, it can be seen that the directivity in the straight direction
becomes narrower as compared with the one in which the convex portion is not formed even if
only the first convex portion 2 e is formed on the outer side wall 2 b. Further, it can be seen from
the results shown in FIG. 4 that the directivity in the vertical direction is further narrowed if the
second convex portion 2 f is formed on the outer side wall 2 b in addition to the first convex
portion 2 e.
[0049]
Further, in the present embodiment, since the second convex portion 2 f is formed at an interval
from the first convex portion 2 e, the contact area between the outer side wall 2 b and the
vibration absorber 5 can be increased, so the outer side Vibration of the side wall 2 b can be
easily absorbed by the vibration absorber 5. Therefore, the first convex portion 2 e is formed
rather than forming one convex portion whose width is equal to the sum of the width 8 a of the
first convex portion 2 e and the width 8 b of the second convex portion 2 f. It is more preferable
to form the second projection 2f and the second projection 2f.
[0050]
Further, in the ultrasonic transducer shown in FIG. 11, the sound absorbing material 3 is filled on
the bottom surface side of the inner case 2a, but absorption of ultrasonic waves is not sufficient
with this sound absorbing material 3 alone, and the detection direction The ultrasound was
emitted in the opposite direction and the reverberation time was extended by the ultrasound that
was reflected back.
[0051]
On the other hand, in the present embodiment, since the opening of the inner case 2a is further
closed with the sound absorbing material 3b, the ultrasonic wave emitted from the opening of
the inner case 2a in the direction opposite to the detection direction is absorbed. And the
reverberation time can be shortened.
03-05-2019
14
Further, since the sound absorbing material 3c is further disposed between the inner housing 2a
and the outer side wall 2b, the ultrasonic wave radiated in the direction opposite to the detection
direction can be absorbed, and the reverberation time can be shortened.
[0052]
In the present embodiment, the first convex portion 2e and the second convex portion 2f are
described as being continuous on the entire periphery of the outer side wall 2b, but the outer
side wall 2b is not necessarily required. It is also possible to make the shape not continuous
along the entire circumference of In this case, from the viewpoint of increasing the rigidity of the
outer side wall 2b more than the ultrasonic transducer shown in FIG. 11, the length of the region
where the convex portion in the outer peripheral (circumferential) direction of the outer side wall
2b is formed is It has been known from the experimental results of the present inventors that the
length must be 50% or more of the entire circumferential length of the outer side wall 2b.
[0053]
Further, in the present embodiment, the second convex portion 2f is disposed in the vicinity of
the center of the outer side wall 2b. However, the present invention is not limited to the vicinity
of the center, and may be disposed at any portion except the first convex portion 2e. Also good.
However, from the viewpoint of not increasing the reverberation time, it is preferable to be
disposed closer to the center than the end of the outer side wall 2b (the end opposite to the
bottom 2c). This is because the reverberation time is extended when the filler 4b for sealing the
outer casing 2b is not located to the end of the outer side wall 2b.
[0054]
The diameter 9a of the first convex portion 2e and the diameter 9b of the second convex portion
2f are preferably twice or less the diameter 9c of the outer casing 2b. According to the
experimental results of the present inventors, in the case of two or more times, the vibration of
the convex portion itself becomes large, and the reverberation time is extended.
[0055]
03-05-2019
15
The width 8a of the first convex portion 2e and the thickness 8b of the second convex portion 2f
are 50% or less of the total width 8c of the entire outer side wall 2b, considering the
reverberation time. It is known from the experimental results of the present inventors that this is
good. Similarly, if the sum of the widths of the projections is 50% or less of the entire width 8c of
the outer side wall 2b, three or more projections can be formed on the outer side wall 2b.
[0056]
Second Embodiment FIG. 5 shows a cross-sectional view of an ultrasonic transducer according to
a second embodiment. The same components as those of the ultrasonic transducer shown in FIG.
1 are denoted by the same reference numerals, so only the differences from the first embodiment
will be described.
[0057]
In the first embodiment, the outer side wall 2b and the first convex portion 2e and the second
convex portion 2f are integrally formed, whereas in the present embodiment, the outer side wall
2b and the first convex portion 2e and The second convex portion 2 f is not integrally formed.
The first convex portion 2e and the second convex portion 2f are made of the same material
(such as aluminum) as the outer side wall 2b, and these are press-fit into the outer side wall 2b.
In addition, as shown in FIG. 5, in the present embodiment, in order to easily press these, the
bottom side portion 2g of the outer side wall 2b is thickened, and the opening side portion 2h is
thin.
[0058]
Also in the present embodiment, since the first convex portion 2 e and the second convex portion
2 f are provided on the outer side wall 2 b, the same effect as that of the first embodiment is
obtained.
[0059]
In addition, the material of the 1st convex part 2e and the 2nd convex part 2f can also be made
into a material different from the outer side wall 2b.
03-05-2019
16
In the case where the material of the projections 2e and 2f is different from that of the outer side
wall 2b, it is desirable to use one having a large density and a large damping effect. For example,
iron, stainless steel, lead, damping alloy etc. It can be used.
[0060]
Further, as a method of joining the outer side wall 2b to the first convex portion 2e and the
second convex portion 2f, methods such as adhesion, welding, caulking, screw fastening or the
like can be used other than press-fitting. Further, also in the present embodiment, the number of
convex portions can be one or three or more as in the first embodiment.
[0061]
Third Embodiment FIG. 6 shows a cross-sectional view of an ultrasonic transducer according to a
third embodiment. The same components as those of the ultrasonic transducer shown in FIG. 1
are denoted by the same reference numerals, so only the differences from the first embodiment
will be described.
[0062]
In this embodiment, a second inner side wall 2i is further provided between the first inner side
wall 2a and the outer side wall 2b in the ultrasonic transducer shown in FIG. It has a structure
having a triple-layered cylinder portion including the first inner case 2a, the second inner case 2i,
and the outer case 2b. The second inner side wall 2i is also integrally formed 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 be
easily integrally molded. Then, a filler 4c is filled in the second inner case 2i.
[0063]
Thus, by making the case 2 into a triple structure, the vibration at the outermost periphery of the
03-05-2019
17
ultrasonic radiation surface 2c can be reduced, and as a result, it is possible to further reduce the
vibration compared to the ultrasonic transducer shown in FIG. The directivity can be narrowed.
In addition, the propagation of vibration to the bumper can be further suppressed as compared
with the ultrasonic transducer shown in FIG.
[0064]
The ultrasonic transducer shown in FIG. 6 has a structure in which the casing 2 has a triplelayered cylindrical portion, but the cylindrical portion may be tripled or more.
[0065]
Fourth Embodiment FIG. 7 shows an appearance of an ultrasonic transducer according to a
fourth embodiment, and a mounting position of the ultrasonic transducer on a vehicle.
[0066]
The ultrasonic transducer shown in FIG. 7 differs from the ultrasonic transducer shown in FIG. 1
in that a notch 12 is provided in the lower region of the second convex portion 2 f.
As described above, by providing the notch 12 in the second convex portion 2f, the housing
passes the center 13 of the bottom portion 2c and is parallel to the horizontal direction when the
housing is viewed from the direction perpendicular to the bottom portion 2c. When a 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 shapes of the second protrusions are symmetrical.
[0067]
And 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.
[0068]
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18
FIG. 8 shows the measurement results of directivity in the ultrasonic transducer having the shape
shown in FIG.
FIGS. 8A and 8B show the measurement results of the directivity in the vertical direction and the
horizontal direction, respectively. FIG. 8 also shows the measurement results of directivity in the
ultrasonic transducer having a shape without a notch. Further, the angle of the horizontal axis in
FIG. 8 (a) corresponds to the angle shown in FIG.
[0069]
In the present embodiment, as shown in FIG. 8B, the directivity in the horizontal direction is
symmetrical in the horizontal direction. Therefore, the detection area in the horizontal direction
of the ultrasonic transducer in the present embodiment is symmetrical with respect to the
ultrasonic transducer.
[0070]
On the other hand, in the vertical direction, the notch 12 is provided in the lower portion of the
second convex portion 2f, so as shown in FIG. 8A, the notch 12 is based on the center 13 of the
bottom portion 2c. The directivity in the vertical direction on the side provided is narrower than
the directivity on the opposite side. That is, the directivity is asymmetric in the vertical direction.
[0071]
Therefore, in the present embodiment, since the ultrasonic transducer is attached to the bumper
with the smaller detection area (directivity) on the lower side, as shown in FIG. 7, the obstacle
detection area (solid line) Can be directed above the detection area (dotted line) without the
notches. As a result, it is not susceptible to the reflection from the ground and curbs, etc., and
long distance obstacle detection becomes possible.
[0072]
As described above, the directivity is asymmetric mainly because the vibration in the groove (thin
portion) 2d connecting the inner case 2a and the outer case 2b and the outermost portion 11 is
03-05-2019
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asymmetrical, and the notch 12 is not It is inferred that on the side provided, the amplitude of
the vibration in the groove 2 d and the outermost peripheral portion 11 is smaller than that on
the side without the notch 12.
[0073]
Further, in the ultrasonic transducer, as shown by a broken line in FIG. 2B, the vertical length of
the bottom of the inner casing 2a is usually longer than that in the horizontal direction.
This is because the directivity becomes narrower as the vibrating portion is longer. Therefore,
when attaching the ultrasonic transducer to the bumper of the vehicle, it is necessary to align the
vertical direction and the horizontal direction of the bottom portion 2c. However, when there is
no mark such as a notch, there arises a problem that the mounting direction is difficult to
understand.
[0074]
On the other hand, in the present embodiment, since the notch 12 is provided on the lower side
of the second convex portion 2f, the notch 12 is used as a mark so that the notch 12 is located
on the lower side. The ultrasonic transducer may be attached to the bumper of the vehicle. For
this reason, in the present embodiment, the ultrasonic transducer can be easily attached to the
vehicle as compared with the case where there is no notch.
[0075]
Moreover, although the case where it has notch 12 in the 2nd convex part 2f was demonstrated
as an example in this embodiment, as shown in FIG. 9, it does not restrict to the method of
providing a notch, The other method is another The shape of the convex portion 2 f can be made
asymmetric.
[0076]
For example, as shown in FIG. 9A, of the second convex portions 2f provided on the entire
periphery of the outer side wall 2b, the lower portion can be cut to have a shape having a cut
03-05-2019
20
portion 14 .
Further, as shown in FIG. 9B, in the lower portion of the second convex portion 2f provided on
the entire periphery of the outer side wall 2b, the width in the direction perpendicular to the
bottom portion is reduced, It is also possible to provide the second protrusion 2 f with a step 15.
In this manner, the second convex portion 2 f provided on the entire periphery of the outer side
wall 2 b is processed to make the shape of the second convex portion 2 f asymmetric, thereby
making the ultrasonic radiation surface 2 c perpendicular (ground The vibration mode in the)
direction can be vertically asymmetric. Also in these cases, the ultrasonic transducer may be
attached to the bumper with the smaller detection area facing downward.
[0077]
Further, in the present embodiment, as shown in FIG. 7, the case where the shape of the second
convex portion 2f is symmetrical in the horizontal direction has been described, but as in the
vertical direction, the second convex portion 2f is It is also possible to make the shape of the
shape asymmetric in the horizontal direction. From this, as in the vibration mode in the vertical
direction, the vibration mode in the horizontal direction can be left-right asymmetrical, and the
detection area can be inclined left (or right).
[0078]
Moreover, although the case where the shape of the 2nd convex part 2f is made asymmetric was
demonstrated in this embodiment, the shape of the 1st convex part 2e can also be made
asymmetric. However, when 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 asymmetric
than the shape of the first convex portion 2e is asymmetric. It is preferable to use
[0079]
Moreover, although the case where the 1st convex part 2e and the 2nd convex part 2f were
provided was demonstrated in this embodiment, the number of convex parts is 1 or 3 or more
similarly to 1st Embodiment. can do. In the case where three or more convex portions are
provided, at least one convex portion may have an asymmetrical shape.
03-05-2019
21
[0080]
Fifth Embodiment FIGS. 10 (a), (b) and (c) respectively show first, second and third examples of
an ultrasonic transducer according to a fifth embodiment. The figure on the left shows the
appearance of the ultrasonic transducer when viewed from the side, and the figure on the right is
a view on arrow B. Moreover, the inner side wall 2a is abbreviate | omitted in these figures.
[0081]
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. And in the ultrasonic transducer
shown in FIG. 10 (a), a notch 16 is provided in a part of the end on the side opposite to the end
connected to the bottom 2c of the outer side wall 2b. ing. Therefore, when the housing 2 is
viewed in a direction perpendicular to the bottom surface portion 2c, the shape of the outer side
wall 2b is asymmetric.
[0082]
As described above, in the ultrasonic transducer according to the first example, the shape of the
outer side wall 2b is asymmetrical with the straight line passing through the center of the bottom
surface 2c as an axis, so the straight line passing through the center of the bottom surface 2c is
On the axis, directivity is also asymmetric. Therefore, in the bottom surface portion 2c, the area
on the side where the notch 16 and the like are formed has narrow directivity, and the obstacle
detection area is narrow.
[0083]
Therefore, the notch is not formed in the outer side wall 2b by attaching the ultrasonic
transducer to the bumper of the vehicle with the narrow detection area on the lower side, and in
the direction perpendicular to the bottom surface portion The detection area can be directed
upward as compared with the case where the shape of the outer side wall 2b when viewed is a
symmetrical shape. As a result, the directivity in the ground direction can be narrowed.
03-05-2019
22
[0084]
The method of making the shape of the outer side wall 2b asymmetric is not limited to the
example described above, and other methods can also be used. For example, in the ultrasonic
transducer shown in FIG. 10 (b), in the outer side wall 2b, a part of the end opposite to the end
connected to the bottom 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
viewing the housing 2 in a direction perpendicular to the bottom surface portion 2c can be made
asymmetric.
[0085]
Further, in the ultrasonic transducer shown in FIG. 10 (c), the outer peripheral side wall 2b is
formed with a convex portion 18 projecting outward in the radial direction. In this manner, the
shape of the outer side wall 2b when viewing the housing 2 in a direction perpendicular to the
bottom surface portion 2c can be made asymmetric.
[0086]
Also, as a mark of the attachment position of the ultrasonic transducer regardless of the
directivity, the side wall of the outer casing 2b or the convex portions 2e, 2f may be simply
notched and processed into a cut portion, a step, a convex portion, etc. it can.
[0087]
In the present embodiment, the case where one convex portion 2e is provided on the extension
of the bottom surface portion 2c has been described, but even in the case where the convex
portion is not provided on the outer side wall 2b, the same as the present embodiment. By
providing a notch or the like on the outer side wall 2b, the same effect as the present
embodiment is obtained.
Further, as in the first embodiment, the number of convex portions can be two or more.
03-05-2019
23
[0088]
(Other Embodiments) In each of the above-described embodiments, although the case where the
inner side wall 2a and the outer side wall 2b are cylindrical has been described as an example,
the present invention is not limited to the cylindrical shape. The present invention is also
applicable to the case of the shape.
[0089]
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 in 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 transducer 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 side view of the ultrasonic transducer as a 1st example in
4th Embodiment, A arrow line view, and a figure which shows the attachment position of an
ultrasonic transducer. It is a figure which shows the measurement result of the directivity of the
ultrasonic transducer in 4th Embodiment. It is a side view of the ultrasonic transducer as another
example in a 4th embodiment, and an A arrow line view. It is the side view of the ultrasonic
transducer as the 1st-3rd examples 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 part of this ultrasonic transducer
vibrates.
Explanation of sign
[0090]
DESCRIPTION OF SYMBOLS 1 ... Piezoelectric vibration element, 2 ... housing | casing, 2a ... inner
side wall (inner housing | casing), 2b ... outer side wall (outside housing | casing), 2c ... bottom
face part (ultrasonic wave radiation surface) 2d ... groove part (thin part) 2e: first convex portion,
2f: second convex portion, 2i: second inner side wall (second inner casing), 3: sound absorbing
material, 4a, 4b: filler, 5: vibration absorber, DESCRIPTION OF SYMBOLS 6 ... Lead wire, 7 ...
03-05-2019
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Bumper, 10 ... Connection part of bottom face part and inner side wall, 11 ... Connection part of
bottom face part and outer side wall, 12, 16 ... Notch part, 14 ... Cut part, 15, 17 ... Stepped part,
18 ... convex part.
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