Ultrasonic sensor arrangement for an ultrasonic transducer concealed on a road vehicle and method for its attachment

Abstract

Ultrasonic sensor arrangement (20) for an ultrasonic transducer concealed on a road vehicle, which converts electrical signals into ultrasonic vibrations and / or ultrasonic vibrations into electrical signals and is or becomes materially bonded to a surface of a body component (1) facing away from the environment (2) at a contact point (5) in order to set the body component (1) into vibrations when generating the ultrasonic signals and to emit an ultrasonic signal into an environment (2) on a side (3) of the body component facing the environment (2) and / or to convert vibrations of the body component (1) caused by ultrasonic echo signals reflected back from the environment (2) into electrical signals, characterized in that a target vibration range (51) of the body component (1) is limited by a cap (21),whose circumferential walls (23) are connected to the surface at their end faces and circumferentially enclose the contact point (5) at a distance from it, wherein the cap (21) is additionally designed to enclose a volume (27) above the desired vibration area (51) of the surface on the side (4) of the body component (1) facing away from the environment (2) almost completely closed, optionally together with a converter housing (26) inserted into a receiving opening (25) of the cap (21).

Description

[0001] The invention relates to an ultrasonic sensor arrangement for a road vehicle and a method for concealing the installation of an ultrasonic transducer in a road vehicle, wherein the ultrasonic sensor arrangement with the corresponding ultrasonic transducer is used in the road vehicle for environmental sensing.

[0002] It is known from the prior art to use sensors to detect the surroundings of a motor vehicle and to evaluate the sensor data in order to detect objects in the surroundings, in particular by determining one or more distances to objects and inferring their presence from these distances. The results obtained in this way are used for various driver assistance systems. For example, the measurement results are used to issue acoustic and / or visual signals to the driver of a road vehicle when the driver approaches an object in the vehicle's vicinity, especially when parking. For the purposes of this text, "road vehicles" refers to all motorized land vehicles.

[0003] Various sensors are known in the prior art for performing environmental sensing. For sensing in the immediate vicinity of the vehicle, which is of particular interest at low speeds, for example when parking, sensors are frequently used in the prior art that emit a signal which is reflected by objects in the vicinity of the vehicle and subsequently detected by the sensor. In one type of measuring sensor, the time of flight between the emission of a transmitted signal and the reception of a reflected transmitted signal, also known as an echo signal, is evaluated. If the propagation speed of the signal is known, the distance traveled by the transmitted signal and the echo signal, and thus the distance to the nearest object, can be deduced from the time of flight.If several sensors are used, which are arranged at a distance from each other on the vehicle, the positions of objects in the surrounding area that send back the echo pulses can also be determined using triangulation methods.

[0004] For the most accurate detection possible, a high signal strength of the reflected signal is desirable. This results in a good signal-to-noise ratio, which is ultimately responsible for the detection quality. Therefore, according to the prior art, ultrasonic sensors are usually integrated into the bumper by creating openings in an outer surface of the bumper into which the transmitting and / or receiving sensors are inserted. Often, the transmitting and receiving devices are integrated into a single ultrasonic transducer, with the same vibrating element being used for both transmitting and receiving the ultrasonic signal. For example, prior art includes ultrasonic transducers that use piezoelectric materials to convert electrical current into mechanical vibrations or mechanical vibrations into electrical signals.

[0005] Such ultrasonic sensors or ultrasonic transducers, which differ in terms of construction and technology used, are known, for example, from the publications DE 197 14 606 A1 and DE 100 18 807 A1.

[0006] In addition to the technology, the demands of manufacturers and buyers regarding the arrangement and design of the component in an end product into which the ultrasonic sensor is to be integrated have also increased recently.

[0007] For example, the sensors and their holders are pre-painted in a matching car color or chrome-plated. Thus, as essentially described in patent DE 100 23 065 B4, mounting holes are punched into painted bumpers, the pre-painted holders are glued in place, and the also pre-painted sensors are clipped into the holder (together with a plastic ring for acoustic decoupling of the sensor from the bumper). In DE 100 23 065 B4, the sensors are therefore not concealed but designed in the same color, making them barely visible.

[0008] Another solution is provided in DE 44 10 895 A1. This patent application describes a method for the concealed installation of a sensor in a motor vehicle exterior part, wherein the sensor is fixedly arranged at a predetermined location on the vehicle exterior part, preferably with the membrane flush with the outer surface of the vehicle exterior part, and wherein at least the location of the sensor is provided with a cover adapted to the contour of the vehicle exterior part. The patent application also describes an associated device.

[0009] US Patent 2007 / 0115102 A1 describes an ultrasonic sensor for a vehicle, comprising a housing fixed to the inner surface of a circumferential element of the vehicle, an ultrasonic vibrator for transmitting and receiving ultrasound, and an ultrasonic transmission element made of a different material than the housing and exhibiting an average acoustic impedance between that of the ultrasonic vibrator and that of the circumferential element. The ultrasonic vibrator is housed within the casing and attached to an end section of the casing facing the circumferential element. The ultrasonic transmission element is located at the end section of the casing and contacts both the ultrasonic vibrator and the vehicle's circumferential element. The casing is preferably snapped onto projections of the circumferential element.

[0010] To prevent an ultrasonic vibrator from being contaminated by a foreign object or intentionally damaged, JP S62-240890 A specifies that the transmitting and receiving ultrasonic vibrator be mounted on an inner wall of a vehicle's bumper. For this purpose, a section of the bumper is made thinner. A vibrating surface of the ultrasonic vibrator is attached directly and tightly to this thin-walled section of the bumper, causing the thinner surface to vibrate and transmit ultrasonic waves to the surface of the bumper. Waves reflected by an object are transmitted back to the vibrating surface of the ultrasonic vibrator by the vibration of the thinner section.Since the obstacle detector is designed to detect objects with the ultrasonic vibrating element mounted on the inner wall of the bumper, it can be prevented that the ultrasonic vibrating element is contaminated with a foreign body such as mud on the surface of the ultrasonic vibrating element or is intentionally damaged.

[0011] For aerodynamic, optical, and manufacturing reasons, it is desirable not to penetrate the surfaces of bumpers, which are often painted the same color as the other body parts of the vehicle. Therefore, sensors that are integrated into body parts, particularly bumpers, of vehicles and are not visible from the outside are known from the prior art. Such an installation of an ultrasonic sensor or ultrasonic sensor array, which is not visible from the outside during normal operation of the vehicle, is referred to as a concealed sensor array. These arrays are thus positioned behind an outer surface, adjacent to that surface of a body component.

[0012] WO 2008 / 125260A1 discloses an arrangement of an ultrasonic transducer designed as a piezoceramic element, which is integrated into a piezoceramic module. The piezoceramic module, which rests directly against the piezoceramic element on its surface facing away from the outer component, is also attached to the outer component by sections that project laterally beyond the piezoceramic element. This is intended to create a mechanical impedance difference between a portion of the outer component and the rest of the outer component, whereby only the portion is excited to vibrate by the piezoceramic element. In some embodiments, ribs are provided on an edge of the portion on the side of the piezoceramic module facing away from the outer component to create the impedance difference.Other embodiments involve modifications to the mass and / or stiffness in the sub-area of ​​the outer component to create an impedance difference.

[0013] From US patent 2007 / 0024432 A1, a concealed arrangement of an ultrasonic sensor is known, which is positioned adjacent to the front wall of a housing. The housing is mounted and attached to an external body component with its front wall in a surface-adherent manner on the side facing away from the environment. The housing is open on the side facing away from the front wall. The piezoceramic element used as the ultrasonic transducer rests flat against the front of the housing. A vibration absorber surrounds the piezoceramic element towards the side walls and the open side. An additional sound-absorbing element is arranged between the vibration absorber and the piezoceramic element on the rear side facing away from the front.In the described embodiment, however, a partial area of ​​the outer body component is excited to vibrate, extending laterally beyond the area against which the housing rests, in which the piezoceramic element used for conversion is arranged.

[0014] From DE 10 2007 045 809 A1, an obstacle detector device is known that comprises a wall section and an ultrasonic sensor. The wall section includes a base section with an inner surface, and the base section extends parallel to an imaginary plane. The ultrasonic sensor is arranged on an inner surface of the base section to transmit and receive the ultrasonic wave via the base section. The ultrasonic sensor contains an ultrasonic transducer and is in contact with the base section via a contact section on the inner surface of the base section. The wall section includes a plurality of stiffness-changing sections arranged on a different section of the inner surface, in an arrangement direction away from the contact section, different from the contact section. The stiffness-changing sections are, for example, arranged as circumferential ribs on the inner surface of the wall section. An outer surface is flat and smooth without openings.

[0015] In the prior art, sensor arrangements for the concealed installation of ultrasonic sensors, where the ultrasonic transducer is located on the side of an outer body panel facing away from the environment to be monitored, ultrasound is emitted not only into this environment but also into the space behind it, i.e., the space in front of the side of the body panel facing away from the environment. Thus, in addition to being emitted into the surroundings of a road vehicle, ultrasound is also emitted into the "interior" of the vehicle. A disadvantage of this is that, typically, other structural parts or vehicle components are located "inside" the vehicle at a distance from the outer body panel, which obstruct the ultrasonic radiation emitted into the vehicle.The ultrasound waves reflect back off the outer body panel, causing it to vibrate. This vibration is detected by the ultrasonic transducer as an echo signal. Due to the short distance between these reflective objects inside the vehicle and the outer body panel, these high-intensity echo signals occur during or immediately after the ultrasound signal is emitted. This makes it difficult or impossible to detect objects located in the immediate vicinity of the vehicle.

[0016] The invention is therefore based on the objective of creating an improved ultrasonic sensor arrangement for concealed installation in a road vehicle and a method for its installation in order to avoid or at least strongly suppress disruptive unintentional emission of ultrasound.

[0017] The invention is solved in an inventive manner by an ultrasonic sensor arrangement with the features of claim 1 and a method with the features of claim 9. Advantageous embodiments of the invention are set forth in the dependent claims.

[0018] The invention is based on the idea of ​​covering an entire sub-area, which is to be excited to vibrate when sending or receiving ultrasound signals, with a flat, closed component, for example a cap, which does not lie flat against the sub-area in order not to be excited to vibrate itself over its entire surface.

[0019] In a preferred embodiment of the invention, the ultrasonic sensor arrangement is provided for a concealed ultrasonic transducer installed on a road vehicle, which converts electrical signals into ultrasonic vibrations and / or ultrasonic vibrations into electrical signals and is or becomes materially bonded to a surface of a body component facing away from the environment at a contact point, in order to set the body component into vibrations when generating the ultrasonic signals and to emit an ultrasonic signal into the environment on a side of the body component facing the environment and / or to convert vibrations of the body component caused by ultrasonic echo signals reflected back from the environment into electrical signals, wherein a desired vibration range of the body component is limited by a cap.the circumferential walls of which are connected to the surface at their end faces and completely enclose the contact point, the cap being additionally designed to almost completely enclose a volume above the target vibration range of the surface on the side of the body component facing away from the environment, optionally together with a transducer housing inserted in a receiving opening of the cap. It is understood that the circumferential walls of the cap, with their end faces attached to the surface, are not in direct acoustic contact with the ultrasonic transducer. This means that a gap exists around the contact point between the ultrasonic transducer and, if applicable, a housing adjacent to the contact point, and the circumferential walls of the cap, whose end faces are attached to the surface.

[0020] The cap prevents the ultrasonic radiation emitted into a rear area, which is generated when the desired vibration area is set into oscillation, from escaping into a rear space. To prevent ultrasonic radiation from being reflected back onto the desired vibration area by the walls of the cap, a preferred embodiment provides for a sound absorber to be arranged within the volume enclosed by the cap.

[0021] In one embodiment of the invention, the sound absorber is designed as a solid element, preferably with a receiving opening for the ultrasonic transducer or its housing. The sound absorber can, for example, consist of a foamed material or another elastic material that exhibits high sound absorption in the ultrasonic frequency range in which the ultrasonic signals are generated by the ultrasonic transducer. The material of the cap is generally a material that forms a sound-hard surface, since the cap material must have sufficient stiffness to delineate the desired vibration range, in which the body component performs transverse vibrations when excited by the ultrasonic transducer, from the rest of the body component and to prevent the propagation of the transverse waves generated during ultrasonic excitation.A sound absorber already formed as a solid element is easier to handle than embodiments in which the sound absorber is injected as foam into the enclosed volume. However, such embodiments have the advantage that any gap that may exist between the cap and an ultrasonic transducer housing, which is arranged in a receiving opening in the cap, can be optimally sealed, at least to some extent, by the sound absorber. Likewise, hybrid forms are also conceivable, in which the sound absorber is essentially formed as a solid element and only the gaps left after the cap and the ultrasonic transducer, including its housing, are arranged on the body component are filled and sealed by means of a foamed sound absorber.

[0022] To avoid hindering the desired vibration of the surface's target vibration range by the sound absorber, the sound absorber is preferably arranged at a distance from the surface of the body component within the enclosed volume. To achieve this, for example, an ultrasonic transducer designed as a solid element can be fixed to a rear wall spaced from the end faces of the surrounding walls, or to the surrounding walls, preferably only partially, using an elastic adhesive. The fixing is designed to minimize sound coupling between the sound absorber and the cap material.

[0023] In a preferred embodiment, the cap is formed separately from the body panel and bonded to it. Here, a connection that is not only materially bonded but also, as far as possible, force-fit is desired in order to ensure optimal limitation of the target vibration range. Transverse vibrations within the target vibration range should not be able to propagate beyond the section where the end faces of the cap contact the body panel around the entire perimeter of the target vibration range. To achieve this, the cap can include ribs or similar features on the side facing away from the end faces of the walls that are bonded to the body panel.One advantage of designing the cap separately from the body panel is that the same body panels can be used for road vehicles equipped with an environmental sensing device with an ultrasonic sensor array, as well as for vehicles without such a device. Additionally, the ultrasonic sensor arrays for such an environmental sensing system and other vehicle systems based on it can be easily retrofitted to already completed vehicles. However, in another embodiment, the cap can be formed integrally with the body panel as a single piece.

[0024] In both described embodiments, it is advantageous if the cap serves as a holder for a transducer housing. For this purpose, the cap preferably has a receiving opening for the transducer housing, so that the transducer and housing can be replaced together if necessary. The ultrasonic transducer is arranged in the transducer housing at a front face, with which the transducer housing and the ultrasonic transducer are bonded to the body panel at the contact point. The ultrasonic transducer and the transducer housing are designed so that no ultrasonic signals are emitted into the rear of the vehicle.For this purpose, the ultrasonic transducer housing can also have a closed surface on the rear side and sound insulation between the actual transducer element and the rear wall of the housing, as is also provided in the volume enclosed by the cap.

[0025] However, other embodiments may provide that the ultrasonic transducer is first attached to the body component at the contact point, then the sound absorber and finally the cap are arranged over the already fixed ultrasonic transducer, possibly together with the sound absorber, and attached to the body component with the end faces.

[0026] Furthermore, the cap is shaped in such a way that it assigns an optimal surface form to the desired vibration range, which is advantageous for optimal ultrasound radiation into the vehicle's surroundings. While it is generally desirable to achieve the broadest possible radiation of ultrasound signals in the azimuthal direction, i.e., parallel to a surface on which the vehicle is moving, radiation perpendicular to this, which is linked to an elevation angle, is generally undesirable in order to concentrate as much of the radiation energy as possible in the horizontal angle range and, on the other hand, to minimize energy radiation directed towards the road surface, where it could generate reflections from irregularities such as manhole covers, speed bumps, and similar features.

[0027] In a preferred embodiment, the opening of the cap's volume towards the surface of the body component facing away from the environment has a larger extent in the plane of the end faces along one direction than perpendicular to it. The arrangement is then preferably such that the direction along which the opening of the cap, defined by the end faces, has a larger extent is oriented horizontally on a body component in the road vehicle. The extent along this direction is preferably selected such that the side lobes caused by mode conversion in the body component during its vibration are radiated almost unimpeded in the horizontal direction.In the direction perpendicular to this, however, an attempt is made to radiate only the main lobe, which is essentially caused by longitudinal vibrations along the propagation direction of the original pressure wave of ultrasound that caused the excitation, into the surroundings.

[0028] In embodiments where only the main beam is to be emitted, the opening of the cap's volume can also be restricted in its horizontal dimension. The horizontal direction of the cap refers here to the direction that is horizontally oriented when installed in the vehicle. Some embodiments provide a circular opening in the volume enclosed by the cap if only the main beam is intended to be emitted.

[0029] A preferred method for attaching a concealed ultrasonic transducer comprises the following steps: bonding an ultrasonic transducer, which converts electrical signals into ultrasonic vibrations and / or ultrasonic vibrations into electrical signals, at a contact point on a surface of a body component facing away from its environment, in order to cause the body component to vibrate when generating the ultrasonic signals and to be able to emit an ultrasonic signal into the environment on a side of the body component facing the environment and / or to be able to convert vibrations of the body component caused by ultrasonic echo signals reflected back from the environment into electrical signals; bonding end faces of circumferential walls of a cap to the surface of the body component facing away from its environment.so that the surrounding walls completely enclose the contact point, thereby defining a target vibration range of the body component, and the cap almost completely encloses a volume above the target vibration range of the surface on the side of the body component facing away from the environment, possibly together with the transducer housing inserted into a receiving opening in the cap. "Almost completely closed" in this context means that the cap may have feed-through openings, for example for the transducer housing or electrical leads. However, these openings are either closed by a further sealing element or filled by the element inserted into or through the opening, the cable or the transducer housing, so that the volume enclosed by the cap and any space outside the cap, except for any potentially existing,The gaps, which are kept as small as possible in terms of their opening width and length, are sealed against each other. These gaps can be sealed with a sound-absorbing material.

[0030] In a further development, it is planned that a sound absorber is placed in the enclosed volume above the target vibration range on the side of the body panel facing away from the surroundings. This can be done simultaneously with the bonding of the cap or by injecting a foaming material after the cap has been positioned and, if necessary, even after the ultrasonic transducer has been installed. To avoid impairing the vibration capability of the target vibration range, it is advantageous to operate the ultrasonic transducer during the foaming process and to set the vibration range into vibration, so that the foamed material does not fill the entire volume, but leaves a section unfilled where the body panel vibrates.

[0031] The invention is explained in more detail below with reference to a drawing. The drawing shows: Fig. 1a, Fig. 1b an unstimulated ( Fig. 1a) and suggested ( Fig. 1b) Bodywork component to illustrate a fashion conversion; Fig. 2 a graphic representation of a laser vibrometer measurement to illustrate the sound emission from a body component on which an ultrasonic transducer is concealed; Fig. 3 a graphical representation of a schematic laser vibrometer measurement to illustrate the sound field radiation as desired; Fig. 4 an exploded view of an ultrasonic sensor arrangement; Fig. 5 a schematic top view of an ultrasonic sensor arrangement; Fig. 6 a sectional view of the ultrasonic sensor arrangement according to Fig. 5; and Fig. 7 another sectional view of the ultrasonic sensor arrangement according to Fig. 5.

[0032] In Fig. 1a is a schematically represented cross-sectional view of a flat body component 1. The body component 1 could, for example, be an outer wall of a bumper of a road vehicle. The body component 1 comprises a side 3 facing an environment 2 and a side 4 facing away from the environment. Fig. Figure 1a shows the body panel at rest without any excitation. If the body panel 1 is excited on the side 4 facing away from the environment 2 by means of an ultrasonic transducer (not shown) at a contact point 5 by means of a pressure wave 8, the direction of propagation of which is indicated by a broad arrow 6, a pressure wave 8 propagates through the body panel 1 parallel to the direction of action of the pressure wave 8. This pressure wave 8 propagates through the body panel 1 perpendicular to its planar extent and generates an ultrasonic pressure wave emitted into the environment 2 parallel to the direction of action of the pressure wave 8, which forms a main lobe 9 of the emitted sound field in the environment 2. In addition, a transverse vibration also forms in the body panel 1, as shown in Fig. Figure 1b illustrates this. The small arrows 7 indicate the local direction of vibration of the body component 1 at an exemplary point in time. Due to this partial mode conversion from the longitudinal vibration of a pressure wave 8 into a transverse vibration, additional side lobes 10 are emitted at an opening angle relative to the original propagation direction of the pressure wave 8. In particular, the radiation of the side lobes 10 occurs not only forward into the surroundings 2, but also into a rearward space 11 on the side 4 of the body component facing away from the surroundings.

[0033] In Fig. Figure 2 schematically depicts the measurement result of a laser vibrometer measurement on a body component 1 designed as a flat surface. An ultrasonic transducer 16 is arranged at a surface-extended contact point 5 in the center of the component, on the side 4 facing away from the surroundings 2. The main lobe 9 and the side lobes 10, which are emitted both into the surroundings 2 and into the rear space 11, are clearly visible in the laser vibrometer measurement result. However, the side lobes 10 emitted into the rear space 11 typically cause echo pulses due to other vehicle components (not shown) located in the rear space 11. These echo pulses make a meaningful evaluation of the echo signals reflected back from the surroundings 2 virtually impossible.

[0034] It should be noted here that, due to the time-of-flight method used for environmental detection, it is not possible to temporally separate the echo pulses originating from the rear compartment 11 from those originating from the monitored environment 2. In particular, it must be considered that, due to the often small distances to other vehicle components in the rear compartment 11, the reflected sound energies in the rear compartment are considerable, so that multiple reflections can occur. This significantly increases the apparent time of flight of the echo pulses, making it impossible to distinguish them from echo pulses originating from a relatively large distance range in the vehicle's environment 2.

[0035] In Fig. Figure 3 schematically depicts a sound field as desired. The main lobe 9 and the side lobes 10 are emitted into the area 2 in front of the body component 1. However, no ultrasound is emitted into the rear space 11. The extent of the vibration area from which the main lobe 9 and the side lobes 10 are emitted is denoted by l.

[0036] To achieve such a situation, an ultrasonic sensor arrangement 20 can be used, as shown schematically in an exploded view in the Fig. Figure 4 shows a section of a body component 1. A cap 21, preferably with end faces 22 of circumferential side walls 23, is bonded to this component. The circumferential side walls 23 and a rear wall 24, preferably formed in one piece, enclose a volume completely, except for a receiving opening 25 for a converter housing 26. The receiving opening 25 is adapted to the converter housing such that the opening is completely closed by the converter housing when the converter housing is arranged in the cap or bonded to a contact point 5 on the side 4 of the body component 1 facing away from the environment 2. The end faces 22 of the side walls 23 define an opening in the enclosed volume.The geometric shape of the opening corresponds to a shape of a target vibration area 51 of the body component 1, which, when the ultrasonic transducer, arranged in the ultrasonic transducer housing 26, is excited, excites the body component to emit ultrasound into the environment 2. Along a first direction 31, the cap 22 has a significantly larger extent than along a second direction 32 oriented perpendicular to the first direction. An opening length l of the cap 21 along the first direction 31 is dimensioned such that it covers an area on the side 4 of the body component 1 facing away from the environment 2, which encloses the area from which the main lobe 9 and the side lobes 10 are emitted into the environment 2 in a plane spanned by the first direction 31 and the main propagation direction 33 of the main lobe 9 of the ultrasonic field 33 (cf. ). Fig. 3) The length of the cap is therefore l + 2Δl, where l is the "length" of the desired oscillation range and Δl is the wall thickness of the side walls 23 at the end faces 22. Parallel to the second direction 32, the opening of the cap 21 has an opening width b. The opening width b is chosen such that the cap 21 only encloses the area at the contact point from which the main lobe of the ultrasonic radiation is emitted.

[0037] A sound absorber 41 is arranged between the rear wall 24 of the cap 21 and the side 4 of the body component 1 facing away from the environment 2. The sound absorber 41 is thus located within the volume enclosed by the cap 21, between the rear wall 24 and the side 4 of the body component 1 facing away from the environment. This ensures that the sound absorber 41 maintains a distance from the surface of the body component 1 on the side 4 facing away from the environment 2. The sound absorber 41 also features a receiving opening 42 for the transducer housing 26. In the illustrated embodiment, the sound absorber 41 is designed as a solid element made of an ultrasound-absorbing material.

[0038] In Fig. Figure 5 shows a top view of the ultrasonic sensor assembly 20, viewed from the body component 1 onto which the ultrasonic sensor assembly 20 is mounted. The end face 22 of a closed, circumferential side wall 23 of the cap 21 is clearly visible. The sound absorber 41 is arranged within the volume enclosed by the cap. In the center, the front of the transducer housing is visible, which is positioned in the receiving opening 42 of the sound absorber 41 or the receiving opening 25 of the cap 21. The base area of ​​the front of the transducer housing essentially determines the size of the surface area of ​​the contact point on the side of the body component facing away from the surroundings. Furthermore, the section lines A and B are shown, which correspond to the respective sectional views of the Fig. 6 and Fig. 7 correspond.

[0039] The actual transducer element (not shown) is arranged flatly on the front surface of the inside of the pot-shaped transducer housing. An opening remaining to the rear space is secured against sound radiation by a sealing element (not shown) and / or sound-absorbing materials. It can be seen that the thickness of the sound absorber 41 perpendicular to the end faces 22 of the surrounding side walls 23 is less than the depth t of the volume 27 enclosed by the cap.This ensures that a gap remains between a front side 43 of the sound absorber and the side 4 of the body component 1 facing away from the environment, so that transverse vibrations can form in the desired vibration area 51 enclosed by the surrounding side walls 23 in order to emit the side lobes in a horizontal plane as defined by the first direction 31 and the main propagation direction 33.

[0040] As from Fig. As can be seen in Figure 7, the surrounding side walls are spaced apart from the contact point 5 with respect to the second direction 32, so that no direct sound coupling from the transducer housing to the surrounding side walls 23 of the cap 21 occurs. The cup-shaped transducer housing can have a surrounding flange-like projection 61, which is designed to completely close the receiving opening 25 in the rear wall 24 of the cap 21 and simultaneously extends backward over the sound absorber 41. The described embodiment enables optimal sound radiation into the surroundings and suppresses sound propagation into the rear space 11, thus preventing disruptive reflections from the rear space 11.

[0041] In the Fig.In the embodiments of the invention shown in Figures 4 to 7, in addition to the emission of the main lobe, emission of side lobes in a first direction 31 is also provided. In other embodiments, it may be provided that the side lobes are not emitted along either the first direction 31 or the second direction 32. In such a case, the length l can be reduced and, for example, chosen to be identical to the width b. In such a case, for example, a circular opening of the enclosed volume 27, and thus of the desired vibration range 51, may result.

[0042] The features described in the individual figures can be used in any combination to realize the invention. Reference symbol list 1 body component 2 Environment 3. Side facing the environment 4. Side facing away from the surroundings 5 Contact point 6 wide arrow 7 small arrow 8. Direction of propagation of the pressure wave 9 Main leg 10 side clubs 11 rear room 15 Middle 16 ultrasound transducers 20 Sensor arrangement 21 cap 22 end faces 23 surrounding side wall / surrounding side walls 24 Back panel 25 Intake opening 26 converter housings 27 enclosed volume 31 first direction 32 second direction l length Δl wall thickness 33 Main direction of spread b width 41 sound absorbers 42 Intake opening 43 Front d Material thickness (sound absorber) t Depth of the enclosed volume 51 Target vibration range 61 flange-like lead

Claims

[1] Ultrasonic sensor arrangement (20) for an ultrasonic transducer concealed on a road vehicle, which converts electrical signals into ultrasonic vibrations and / or ultrasonic vibrations into electrical signals and is or becomes materially bonded to a surface of a body component (1) facing away from the environment (2) at a contact point (5) in order to cause the body component (1) to vibrate when generating the ultrasonic signals and to emit an ultrasonic signal into an environment (2) on a side (3) of the body component facing the environment (2) and / or to convert vibrations of the body component (1) caused by ultrasonic echo signals reflected back from the environment (2) into electrical signals, characterized by, that a target vibration range (51) of the body component (1) is limited by a cap (21) whose circumferential walls (23) are connected to the surface at their end faces and circumferentially enclose the contact point (5) at a distance from it, wherein the cap (21) is additionally designed to enclose a volume (27) above the target vibration range (51) of the surface on the side (4) of the body component (1) facing away from the environment (2) almost completely closed, optionally together with a converter housing (26) inserted into a receiving opening (25) of the cap (21). [2] Ultrasonic sensor arrangement (20) according to claim 1, characterized by , that a sound absorber (41) is arranged in the enclosed volume (27). [3] Ultrasonic sensor arrangement (20) according to claim 2, characterized by that the sound absorber (41) is a solid element with a receiving opening (42) for the ultrasonic transducer or its housing (26). [4] Ultrasonic sensor arrangement (20) according to claim 2, characterized by , that the sound absorber (41) is injected as foam into the enclosed volume (27). [5] Ultrasonic sensor arrangement (20) according to one of claims 2 to 4, characterized by , that the sound absorber (41) is arranged at a distance from the surface of the body component (1) in the enclosed volume (27). [6] Ultrasonic sensor arrangement (20) according to one of the preceding claims, characterized by , that the cap (21) is formed separately from the body component (1) and is glued onto the body component (1). [7] Ultrasonic sensor arrangement (20) according to any one of claims 1 to 5, characterized by , that the cap (21) is formed integrally with the body component (1) in one piece. [8] Ultrasonic sensor arrangement (20) according to one of the preceding claims, characterized by , that the cap (21) is designed as a holder for the converter housing (26). [9] Method for installing a concealed ultrasonic transducer comprising the steps: material-bonded connection of an ultrasonic transducer, which converts electrical signals into ultrasonic vibrations and / or ultrasonic vibrations into electrical signals, at a contact point (5) on a surface of a body component (1) facing away from an environment (2), in order to set the body component (1) into vibrations when generating the ultrasonic signals and to be able to emit an ultrasonic signal into an environment (2) on a side (3) of the body component (1) facing the environment (2) and / or to be able to convert vibrations of the body component (1) caused by ultrasonic echo signals reflected back from the environment (2) into electrical signals, Bonding end faces (22) of circumferential walls (23) of a cap (21) to the surface of the body component (1) facing away from the environment (2), such that the circumferential walls (23) completely enclose the contact point (5) and thereby define a target vibration range (51) of the body component (1) and the cap (21) encloses a volume (27) above the target vibration range (51) of the surface on the side (4) of the body component (1) facing away from the environment (2) almost completely closed, optionally together with the converter housing (26) inserted into a receiving opening (25) of the cap (21). [10] Method according to claim 9, characterized by , that a sound absorber (41) is arranged in the enclosed volume (27) above the target vibration range (51) on the side (4) of the body component (1) facing away from the environment (2).

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