JPS60173996

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DESCRIPTION JPS60173996
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an
ultrasonic transducer, and more particularly to an ultrasonic transducer provided at the rear of a
vehicle to detect the presence of an obstacle behind the vehicle. [Background Art] In recent years,
an ultrasonic transducer has been installed on a vehicle's vehicle bumper, etc., and an ultrasonic
wave is emitted to the rear of the vehicle, and the time to the reflected wave is reflected by the
obstacle and returns to the obstacle A rear obstacle detecting device has been proposed which
detects the rear end of the vehicle and makes the backward movement of the vehicle safe. The
ultrasonic transducer used in such a device usually comprises an ultrasonic transducer and a
reflection plate for reflecting and transmitting the ultrasonic wave emitted from the transducer in
the horizontal direction, but the installation location of the transducer As mentioned above, there
are many positions relatively close to the road surface as described above, and when splashed
mud water or the like adheres to the vibrator or the reflection plate, the function is deteriorated.
Then, in order to prevent adhesion of muddy water etc., it is possible to store a vibrator and a
reflecting plate in a cylindrical housing, but a part of ultrasonic waves transmitted is reflected by
a cylinder wall and the road surface direction below. There is a problem that the reflected wave
from the road surface is reflected by the cylinder wall and received by the cylinder wall, and an
object near the road surface is erroneously detected as an obstacle. SUMMARY OF THE
INVENTION In view of the above problems, the present invention provides an ultrasonic
transducer having a cylindrical housing, in which reflection of ultrasonic waves at the cylindrical
wall of the housing is reduced to improve the directivity characteristic of the ultrasonic
transducer. Intended to provide. In the ultrasonic transducer according to the present invention,
a projection is formed at a position along at least the opening of the inner wall of the housing,
and the projection has a smooth curved surface at least in the housing axial direction. is there.
[Embodiment 1] In FIG. 1, an ultrasonic transducer 1 is embedded in a vehicle interior area R of a
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vehicle similarly formed of a resin foam molded body R1 with a skin R2 of resin. The transducer
1 is generally in the form of a square tube (see FIG. 2), with its opening located on the surface of
the pamper R and directed rearward (leftward in FIG. 1) of the vehicle. That is, the transmitter /
receiver 1 has the resin cylindrical housing 11 open at one end, and the housing 11 is screwed
and fixed to the surface R1 of the bread scrap R at several places of the open end face (not
shown) ). A reflector 12 is provided in the housing 11 along the closed end face. The reflection
plate 120 is a paraboloid with its lower surface gradually curved backward. A holding member
13 made of rubber is provided on the upper part of the housing 11 so as to be exposed in the
cylinder, and an ultrasonic transducer 14 is disposed in the recess of the holding member 3
obliquely forward. The vibrator 14 is positioned at the focal point of the reflecting surface 121 of
the reflecting plate 12.
The closed end face of the housing 11 is provided with a long hole 112 for draining along the
upper end of the reflection plate 12, while the lower surface of the holding member 13 has a
projection obliquely toward the upper end of the reflection plate 12. 131 is formed. The
protrusion 131 has a rear surface 131 a facing the ultrasonic transducer 14 as a smooth curved
surface. A cylindrical hood 15 made of rubber is fitted into the housing 11 from the opening for
improving the appearance. The hood 15 covers the surface of the bread chips R on the opening
periphery of the housing 11 and the inner peripheral surface of the housing 11. Then, round
bars 16a and 16b are respectively joined to the inner peripheral surface of the open end of the
hood 15 along the open end at substantially opposite positions above and below to form a
protrusion. The radius of the round bars 16a, 16b is 1?4 to 5 times the wavelength of ultrasonic
waves used. The reflecting surface 121 of the reflecting plate 12 is also curved in the width
direction to prevent the ultrasonic wave from being dispersed to the left and right. The ultrasonic
transducer 14 is connected to a rear obstacle detection device mounted on a vehicle via a lead
wire of the recessed path. The ultrasonic waves emitted from the vibrator 14 are reflected by the
reflecting surface 121 and are transmitted outward from the opening in the horizontal direction
parallel to the housing axis. Then, the reflected wave that is reflected by the obstacle of the
concave road that exists in the rear of the vehicle and is incident on the opening parallel to the
housing axis is reflected again by the reflecting surface 121 and reaches the vibrator 1. Here,
FIG. 3 shows the directivity characteristics of the ultrasonic transducer l. That is, the drawing
shows the reception sensitivity of the ultrasonic wave incident into the housing 11 at an angle
from the vertical direction with respect to the housing axis. Negative angles in the figure indicate
downwards. The line y in the figure shows the directional characteristics when the round bars
16a and 16b are not provided, and it is known from the figure that ultrasonic waves incident in a
horizontal direction parallel to the housing axis are most sensitively received. The sensitivity of
the incident ultrasonic waves is also relatively high, and this may cause a reflected wave from the
road surface to be received to falsely detect an obstacle. The inventors considered that the
incident ultrasonic waves were repeatedly reflected by the inner wall of the hood 15 to reach the
ultrasonic transducer 14 as a cause of the high sensitivity of the ultrasonic waves incident from
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the lower side. Therefore, it has a smooth curved surface and its radius to prevent ultrasound
from being reflected as a phase-matched wave in a specific direction and also to cause the
cancellation of ultrasound by diffraction effects. Are provided in the opening of the hood 15 as
described above. The reception sensitivity at this time is shown by line X in FIG.
The provision of the round bars 16a and xab effectively lowers the reception sensitivity to the
incoming ultrasonic waves from below, thereby causing curbs and the like near the road surface
without interference with the Ryavampa R. There will be no false detection as an obstacle. On the
other hand, in the above-mentioned transducer 1, the rainwater invading through the route as
shown by the chain line in FIG. 1 rises along the reflecting surface 121, and most of the
rainwater is discharged from the long hole 112. However, part of the rain water collides with the
lower surface of the holding member 131 and scatters to the vibrator 14 side. Thus, in the
present invention, it is effectively prevented that the rainwater scattered by the projections 131
formed on the holding member 13 infiltrates into the vibrator 14 (arrows in the figure). In the
present invention, since the rear surface 131a of the projection 131 facing the vibrator 14 is a
smooth curved surface, the directivity characteristic of the transducer 1 is not adversely affected.
That is, in FIG. 4, a line X 'indicates the directivity characteristic of the present invention, and a
line y' indicates the directivity characteristic when the rear surface 131a is a plane. As is known
from the drawing, by forming the rear surface 131a as a smooth curved surface, it is possible to
suppress the reception sensitivity to ultrasonic waves incident on the transmission / reception
device 1 from below. [Embodiment 2] In FIG. 5, on the upper and lower inner peripheral surfaces
of the hood 15, chevron shaped ridges 151 having a smooth curved surface in section are
formed repeatedly toward the closed end from the opening. The radius of curvature of the
protrusion 151 is 1/4 to 5 times the wavelength of the ultrasonic wave to be used. In the figure,
reference numeral 152 denotes a water draining hole for draining the water accumulated
between the protrusions 151, and it is a plurality of film spots in the width direction along the
protrusions 151. According to the present embodiment, the sensitivity to ultrasonic waves
incident from below can be suppressed to a further lower level than in the above embodiment.
The protrusions 151 are not necessarily required to be formed at an equal pitch. [Embodiment 3]
In FIG. 6, on the upper and lower sides of the hood 15, spheres 17 having a radius of 1?4 to 5
times the wavelength of ultrasonic waves are arranged along the upper and lower sides.
According to this embodiment, the same effect as that of the first embodiment can be obtained.
The spheres 17 do not necessarily have to be equally spaced. In the above embodiments, the
projections are formed on the upper and lower surfaces of the housing opening to improve the
directivity of the ultrasonic transducer in the vertical direction, but if the projections are formed
on the left and right surfaces, the directivity in the left and right directions is improved. be able
to. [Effects of the Invention] As described above, the ultrasonic transducer according to the
present invention is characterized in that the projection having a smooth curved surface at least
in the axial direction of the housing is formed at a position along at least the opening of the inner
wall of the cylindrical housing. The directivity characteristic is improved by reducing the
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reflection of the ultrasonic wave in the cylinder wall, and in particular, in the rear obstacle
detection device of the vehicle using the ultrasonic wave, the false detection of the obstacle is
prevented in advance. .
[0002]
Brief description of the drawings
[0003]
1 to 4 show a first embodiment of the present invention, and FIG. 1 is a whole cross-sectional
view of an ultrasonic transducer according to the present invention provided in a carrier, and
FIG. 2 is an arrow A in FIG. Figure 3 is a front view of the ultrasonic transducer, and Figures 3
and 4 show the directivity characteristics of the ultrasonic transducer, and Figure 5 is an
ultrasonic transducer showing a second embodiment of the present invention. FIG. 6 is a front
view of an ultrasonic transducer showing a third embodiment of the present invention.
R ...... Ryapanpayu ...... ultrasonic transducer 11 ...... housing 12 ...... reflector 14 ...... ultrasonic
transducer 16a, 16b иииииииииии Round rod (protrusions with a circular cross-section) 51
ииииииииииииииииииииииииииииииииииииииииииииииииии иии Degree) fX 4 times ? (button Fig. 5
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