ULTRASOUND SENSOR FOR A MOTOR VEHICLE AND MOTOR VEHICLE

Description

[0001] The present invention relates to the field of ultrasonic sensors for motor vehicles and more particularly to an ultrasonic sensor for a motor vehicle and a motor vehicle.

[0002] Ultrasonic sensors comprising a housing and an ultrasonic membrane arranged in a housing opening of the plastic housing are known, for example from DE 10 202 200 639 A1. Such an ultrasonic sensor can be used to measure a distance to an object in the vehicle's surroundings or to an object in the vehicle's interior using the pulse-echo method. The ultrasonic membrane, excited by a sound transducer element attached to it, emits energy in the form of an ultrasonic signal. The sound transducer element then detects vibrations of the ultrasonic membrane resulting from an echo signal returning from the vehicle's surroundings or the interior. The distance to the object is determined based on the signal propagation time. Such measurements are used, for example, by a vehicle's parking assistance system.

[0003] After the ultrasonic signal is transmitted, the structural vibrations of the ultrasonic sensor that were excited during the transmission of the ultrasonic signal must first decay. During this decay time, the ultrasonic sensor is blind and cannot detect any echo signal.

[0004] It is therefore desirable to improve the structural dynamics of an ultrasonic sensor. In particular, transfer paths to structural elements capable of efficiently storing energy, such as the plastic housing and, in particular, the metallic contact elements arranged therein, should be eliminated as far as possible. This is conventionally achieved, for example, by placing a decoupling element, such as a silicone ring, between the ultrasonic membrane and the plastic housing.

[0005] In DE 19 212 299 639 A1, ribs are arranged on the decoupling ring in a contact area between the decoupling ring and the ultrasonic membrane pot or the plastic housing to reduce the rigidity of the decoupling ring.

[0006] DE 10 2013 022 048 A1 also teaches such an ultrasonic sensor with a decoupling ring structured by ribs.

[0007] DE 10 2106 2321 535 A1 teaches an ultrasonic transducer with a housing and a diaphragm cup. The diaphragm cup is housed in a receiving area of ​​the housing. The receiving area has several elevations on a radially circumferential axial stop surface arranged perpendicular to the longitudinal axis. These elevations are also arranged radially circumferentially and their function is not disclosed. The receiving area encloses the diaphragm cup with an elastic decoupling ring positioned flush between them.

[0008] US 2016 / 0008796 A1 teaches that, in an ultrasonic transducer, a preferably elastic fixing element couples a diaphragm cup, referred to as a "case," to the housing. The elastic fixing element has circumferential ribs on an outer periphery that engage in recesses in a plastic element that are shaped to correspond to the ribs.

[0009] Against this background, the object of the present invention is to provide an ultrasonic sensor with improved structural dynamics.

[0010] According to a first aspect, an ultrasonic sensor for a motor vehicle according to claim 1 is proposed.

[0011] In particular, the decoupling element does not fully contact the inner surface of the plastic housing in an area in which the ribs are formed.

[0012] In particular, the decoupling area between each two adjacent ribs does not lie or does not lie completely on the inner surface of the plastic housing.

[0013] Particularly preferably, the decoupling element in the region in which the ribs are formed rests only on the tips of the ribs.

[0014] Accordingly, a portion of the inner surface of the plastic housing that is in contact with the decoupling element (hereinafter also referred to as the "supporting portion" of the inner surface) is advantageously reduced compared to comparative examples in which no ribs are provided on the inner surface of the plastic housing and / or in which, despite ribs being provided on the inner surface of the plastic housing, the decoupling element also rests between the ribs on the inner surface of the plastic housing, for example because it is pressed into the spaces between the ribs and / or has a shape complementary to the ribs.

[0015] The decoupling element is particularly made of a soft material that is at least softer than the plastic housing and softer than a material of the diaphragm assembly. The diaphragm assembly is made of aluminum, for example. The decoupling element can be made of silicone, for example. Plastic and aluminum can therefore also be referred to as "hard" materials.

[0016] The proposed reduction in the load-bearing component can, due to the structural vibrations of the membrane assembly, alternately cause increased compression of the soft decoupling element and increased relaxation of the, preferably prestressed, connection between the soft decoupling element and the hard plastic housing. This reduces the energy transfer from the ultrasonic membrane via the decoupling element to the plastic housing. Thus, acoustic decoupling can advantageously be provided at an interface between the decoupling element and the plastic housing.

[0017] The ribs are formed on the inner surface of the hard plastic housing and not on the soft decoupling element. Thus, the ribs are formed on the harder or stronger component. Accordingly, even during preloaded assembly, the decoupling element is hardly deformed, and the load-bearing portion remains reduced even after assembly.

[0018] The inner surface of the plastic housing is in particular a surface that defines an edge surface of the housing opening.

[0019] The decoupling element is arranged, in particular, between the inner surface of the plastic housing and the membrane assembly such that the membrane assembly and the plastic housing do not directly touch each other anywhere. In other words, the decoupling element is arranged, in particular, in an entire area in which the membrane assembly and the inner surface of the plastic housing overlap.

[0020] Silicone as a material for the decoupling element is also advantageous in that its behavior hardly changes over the range of operating temperatures typical for the automotive sector.

[0021] In addition to the ultrasonic diaphragm, the diaphragm assembly can detect other components of the ultrasonic sensor that are allowed to oscillate together with the diaphragm, either because this is technically necessary or because these components have a low or negligible weight. All other components of the ultrasonic sensor, in contrast, are housed in the plastic housing and are thus acoustically decoupled from the diaphragm assembly.

[0022] In particular, the membrane assembly can comprise a sound transducer element, such as a piezoelectric element or the like, for exciting and detecting vibrations of the ultrasonic membrane. The sound transducer element can be glued or otherwise fixed to the inner side of the ultrasonic membrane. The membrane assembly can further comprise a jacket-shaped side wall against which the decoupling element can rest. In this case, at least a portion of the jacket wall can be arranged in the housing opening of the plastic housing, with the decoupling element being arranged between the housing opening and the portion of the jacket wall, and another portion of the jacket wall and the ultrasonic membrane can protrude from the plastic housing.

[0023] The term "arranged in a housing opening of the plastic housing" can therefore be understood to mean that at least a portion of the membrane assembly is arranged within the housing opening of the plastic housing.

[0024] According to one embodiment, the decoupling element lies flat against the membrane assembly.

[0025] In particular, the decoupling element rests against the membrane assembly over its entire surface and / or flush with it. In other words, no ribs are formed on the membrane assembly, and a portion of the membrane assembly's outer surface that is in contact with the membrane assembly's decoupling element is not reduced.

[0026] Accordingly, in addition to the acoustic decoupling, a damping effect is achieved, since the full-surface or flush design of the interface between the decoupling element and the diaphragm assembly without ribs allows vibration energy of the diaphragm assembly to be dissipated in the decoupling element through internal friction. Furthermore, the fixation of the diaphragm assembly in the attached decoupling element in the plastic housing is simplified.

[0027] According to a further embodiment, the membrane assembly is mounted under prestress in the housing opening.

[0028] In particular, the membrane assembly and the decoupling element can be mounted together under prestress in the housing opening.

[0029] Accordingly, advantageously, no fixing means are required to fix the diaphragm assembly to the plastic housing, which could represent a "leakage" for vibration energy.

[0030] The diaphragm assembly comprises a diaphragm cup having a bottom forming the ultrasonic diaphragm and a shell formed integrally with the bottom, wherein the diaphragm cup is inserted into the housing opening along an axial direction of the housing opening.

[0031] The diaphragm cup can, in particular, be a one-piece deep-drawn component made of aluminum. "One-piece" construction refers, in particular, to primary forming in a single operation.

[0032] "Inserted into the housing opening" means, in particular, that at least a portion of the diaphragm cup (specifically, a portion of the casing) is inserted into the housing opening. The diaphragm cup is, in particular, partially inserted into the housing opening and partially protrudes from the housing opening, with the base of the diaphragm cup facing axially outward and not inserted into the housing opening.

[0033] In particular, the axial direction of the housing opening can coincide with an axial direction of the diaphragm cup. Furthermore, in a section where the casing of the diaphragm cup is inserted into the housing opening, an outer circumference of the casing of the diaphragm cup can coincide with a circumference of the housing opening, or essentially coincide in such a way that a gap remains in which the decoupling element is arranged between the outer circumference of the casing and the inner surface of the plastic housing in the housing opening.

[0034] The shell of the diaphragm cup, the housing opening into which the diaphragm cup is inserted, and the base of the diaphragm cup, which is located outside the plastic housing, can each have a substantially round, oval, or elliptical cross-section. A non-completely round cross-section can result in an anisotropy of the ultrasonic diaphragm's radiation characteristics, which is advantageous for environmental measurement.

[0035] The membrane cup's casing protects the ultrasonic sensor from the ingress of water and foreign matter in the section where it is not inserted into the housing opening. In the section where the casing is inserted into the housing opening, a flush and tight seal is achieved thanks to the decoupling element, which rests against the casing's entire surface.

[0036] At least some of the ribs on a shell portion of the inner surface of the plastic housing project radially inward and extend in the axial direction of the housing opening.

[0037] Accordingly, radial structural vibrations of the diaphragm cup can be advantageously acoustically decoupled from the plastic housing. Furthermore, the fact that the ribs on the shell section of the inner surface extend in a radial direction simplifies the insertion of the diaphragm cup and the decoupling element into the housing opening of the plastic housing along the inner surface of the plastic housing during assembly. This is especially true when the diaphragm cup is installed in the housing opening under a defined preload.

[0038] It should be noted that the housing opening may be substantially cylindrical and the shell portion of the inner surface of the plastic housing may accordingly define a shell-shaped edge surface of the housing opening.

[0039] According to a further embodiment, the ribs extending in the axial direction form an insertion bevel for inserting the diaphragm cup and the decoupling element.

[0040] This means that the amount by which the axially extending ribs project radially into the housing opening can gradually increase along the axial extent of these ribs from the outside to the inside. In other words, the ribs can define a larger free diameter of the housing opening at an axially outward position than at an axially inward position.

[0041] Accordingly, the insertion of the diaphragm cup and the decoupling element is simplified at the time of assembly. In particular, the preload of the assembly can gradually increase as the diaphragm cup and the decoupling element are inserted into the housing opening.

[0042] According to a further embodiment, at least a portion of the decoupling element is arranged in an entire first overlap region in which an outer surface of the jacket of the diaphragm cup and the jacket portion of the inner surface of the plastic housing overlap each other, lies flat against the jacket of the diaphragm cup and encloses the jacket of the diaphragm cup in an annular manner, wherein the ribs running in the axial direction are formed in the jacket portion of the inner surface of the plastic housing in the first overlap region.

[0043] Accordingly, the decoupling element can be arranged between the entire first overlap region, in which the diaphragm cup (the outer surface of the shell) and the shell section of the inner surface of the plastic housing radially overlap. The proposed acoustic decoupling is achieved by providing the axially extending ribs in the first overlap region and reducing the load-bearing portion of the shell section of the inner surface of the plastic housing. In addition, the decoupling element can have a damping effect due to the planar, in particular full-surface, contact of the decoupling element with the shell of the diaphragm cup.

[0044] According to a further embodiment, at least some of the ribs protrude at a bottom portion of the housing opening in the axial direction of the housing opening and extend annularly in a circumferential direction of the housing opening.

[0045] Accordingly, axial structural vibrations of the diaphragm cup can be advantageously acoustically decoupled from the plastic housing. Because the ribs extend in a ring-shaped manner in the circumferential direction of the housing, i.e., in particular, around the entire circumference of the housing opening, a sealing effect can be achieved.

[0046] It should be noted that, in addition to the skirt portion, the inner surface of the plastic housing may also have a bottom portion that defines at least portions of an edge surface at the bottom portion of the housing opening. Accordingly, the ribs projecting in the axial direction are also ribs formed on the inner surface of the plastic housing.

[0047] According to a further embodiment, the bottom section of the housing opening is formed by an annular console formed integrally with the plastic housing, located in the axial direction and projecting radially inward.

[0048] The bracket can form a stop for the casing of the diaphragm cup. Thus, the positioning of the bracket can determine how far the diaphragm cup can be inserted into the housing opening during installation of the ultrasonic sensor. Because the bracket is ring-shaped, i.e., open particularly in a central area, it is still possible to use a decoupling wire or similar to connect the ultrasonic diaphragm of the diaphragm cup to electronic components located on the other side of the bracket inside the plastic housing.

[0049] According to a further embodiment, at least a portion of the decoupling element is arranged in an entire second overlap region in which an end face of the jacket of the diaphragm cup and the bottom portion of the housing opening overlap each other, and lies flat against the end face of the jacket of the diaphragm cup, wherein the annular ribs extending in the radial direction are formed on the bottom portion of the housing opening in the second overlap region.

[0050] Accordingly, the decoupling element can be arranged between the entire second overlap area, in which the diaphragm cup (the end face of the casing) and the bottom section of the housing opening (the surface of the annular bracket) axially overlap each other. The proposed acoustic decoupling is achieved by providing the annular or circumferential ribs in the second overlap area and reducing the load-bearing portion of the bottom section (the bracket surface). In addition, the decoupling element can have a damping effect due to the planar, in particular full-surface, contact of the decoupling element with the end face of the casing of the diaphragm cup.

[0051] In particular, the casing of the diaphragm pot can be widened on its end face facing the console, for example widened outwards like a flange, in order to increase the axial overlap area and further improve the damping of axial vibrations.

[0052] According to a further embodiment, an annular cover is placed from the outside onto the diaphragm pot and the plastic housing, covers exposed sections of the decoupling element and is connected from the outside to the plastic housing, wherein the annular cover is a two-component material with a hard and a soft material component and the soft material component rests on the outer surface of the jacket of the diaphragm pot, on the exposed sections of the decoupling element and on a front edge of the plastic housing.

[0053] The soft material component is at least softer than the hard material component. The soft material component can be formed, in particular, from the same material as the decoupling element, for example, silicone. The hard material component can be formed, in particular, from the same material as the plastic housing, for example, plastic.

[0054] The lid (especially the hard material component of the lid) can be connected to the plastic housing from the outside, for example by laser welding.

[0055] The cover can serve as a fastening element for securing the diaphragm cup to the housing. The diaphragm cup is advantageously secured to the housing in such a way that there is no direct contact between the diaphragm cup and the plastic housing at any point. Also, there is preferably no contact between the diaphragm cup and the hard material component of the cover. The cover can only rest against the diaphragm cup with the soft material component. This counteracts energy transfer from the diaphragm cup via the cover to the plastic housing.

[0056] According to a second aspect, a motor vehicle with at least one ultrasonic sensor as described above is proposed.

[0057] The features, advantages and embodiments described for the ultrasonic sensor of the first aspect also apply accordingly to the motor vehicle of the second aspect.

[0058] The motor vehicle can, in particular, be a passenger car or a truck. The motor vehicle can have an assistance system, such as a driver assistance system or a parking assistance system, which can be configured, in particular, for partially or fully autonomous driving of the vehicle. Partially autonomous driving is understood, for example, to mean that the assistance system controls a steering device and / or an automatic gearshift. Fully autonomous driving is understood, for example, to mean that the assistance system also controls a drive device and a braking device. The assistance system can be implemented using hardware and / or software. In a hardware implementation, the assistance system can be embodied, for example, as a computer or a microprocessor.In a software implementation, the assistance system can be embodied as a computer program product, as a function, as a routine, as part of a program code, or as an executable object. In particular, the assistance system can be embodied as part of a higher-level control system of the vehicle, such as an ECU (Engine Control Unit). The assistance system can use the proposed ultrasonic sensor to monitor or measure the surroundings of the motor vehicle using ultrasonic measurements based on the pulse-echo method.

[0059] It will be understood that improvements and modifications may be made to the present invention described in detail above and below without departing from the scope of the invention as disclosed in the appended claims.

[0060] Further advantageous embodiments and aspects of the invention are the subject of the dependent claims and the exemplary embodiments of the invention described below. The invention is explained in more detail below using preferred exemplary embodiments with reference to the accompanying figures. Fig. 1 shows a schematic vertical sectional view of an ultrasonic sensor according to a first embodiment; Fig. 2 shows a simplified view of an ultrasonic sensor according to a second embodiment; Fig. 3 shows a horizontal section AA of the views in Fig. 2 , 4 , 5 and 6 ; Fig. 4 shows a vertical section BB of the view from Fig. 3 ; Fig. 5 shows a vertical section CC of the view from Fig. 3 ; Fig. 6 shows a vertical section DD of the view from Fig. 3 ; and Fig. 7 shows a motor vehicle according to a third embodiment.

[0061] In the figures, identical or functionally equivalent elements have been given the same reference numerals unless otherwise stated.

[0062] Fig. 1 shows a schematic sectional view of an ultrasonic sensor 1 according to a first exemplary embodiment. The ultrasonic sensor has a plastic housing 2 and a membrane assembly 3. The membrane assembly is arranged in a housing opening 4 of the plastic housing 2 and, in particular, comprises an ultrasonic membrane (not explicitly shown). A decoupling element 6 is arranged between an inner surface 5 of the plastic housing 2, which defines an edge of the housing opening 4, and the membrane assembly 3.

[0063] The decoupling element is made of a soft material, such as silicone. The plastic housing 2, in contrast, is made of a hard material. The membrane assembly 3, for example, is also made of a hard material, such as aluminum.

[0064] A plurality of ribs 7 are formed on the inner surface 5 of the plastic housing 2. The decoupling element 6 rests against the ribs 7. Accordingly, the contact portion of the inner surface 5 of the plastic housing (the portion of the inner surface 5 that is in contact with the decoupling element 6) is significantly less than 100% and, in particular, reduced compared to a case in which the ribs 7 were not provided. This means that there is not full-surface contact between the decoupling element 6 and the inner surface 5 of the plastic housing 2.

[0065] Fig. 1 shows only suggested aspects of the ultrasonic sensor 1. Of course, the ultrasonic sensor 1 can also have further elements not shown. Thus, the membrane group 3 can further comprise a sound transducer element such as a piezo element or the like, which can be glued from the inside to the ultrasonic membrane of the membrane assembly 3 and serves to excite and detect vibrations of the ultrasonic membrane of the membrane assembly 3. The sound transducer element (not shown) can be electrically contacted with a decoupling wire (not shown). In the housing 2, furthermore, in a Fig. 1 A circuit board with electronic components for controlling the sound transducer element and for communication with a control unit external to the ultrasonic sensor 1 may be provided in an area not shown.

[0066] In the Fig. 1 In the ultrasonic sensor 1 shown, the contact area of ​​the inner surface 5 of the plastic housing 2 is reduced, and the ribs 7 are formed on the side of the harder of the two elements (the plastic housing 2). Accordingly, the contact area advantageously remains reduced even when the diaphragm assembly 3 is mounted under prestress in the housing opening 4. This advantageously achieves particularly good acoustic decoupling between the diaphragm assembly 3 and the plastic housing 2, and assembly is simplified.

[0067] According to a preferred development of the first embodiment, which is shown in Fig. 1 As shown, a portion of an outer surface of the diaphragm assembly that is in contact with the decoupling element 6 is not reduced. In other words, the decoupling element 6 lies flush or over its entire surface against the diaphragm assembly 3. Accordingly, vibration energy of the diaphragm assembly 3 can advantageously be dissipated in the decoupling element 6 through internal friction, and the decoupling element 6 also performs a damping function.

[0068] Fig. 2 shows a simplified view of an ultrasonic sensor 1 according to a second embodiment. The following mainly describes differences between the second and first embodiments.

[0069] The ultrasonic sensor 1 has a plastic housing 2 in which the electronic components and the like (not shown) discussed above with reference to the first example are arranged. The membrane assembly of the ultrasonic sensor 1 is designed as a membrane pot 3, which has a base 8 and a casing 9 (shell-shaped wall) and in its interior (in Fig. 2 (not visible) is hollow. The diaphragm cup 3, consisting of a base 8 and a casing 9, is formed as a single-piece deep-drawn aluminum component. The base 8 of the diaphragm cup 3 forms the ultrasonic diaphragm of the ultrasonic sensor 1 and is therefore also referred to as the ultrasonic diaphragm 8.

[0070] In Fig. 2 It can be seen that a section of the diaphragm cup 3 protrudes from the plastic housing 2. An annular cover 10 is placed on the outside of the diaphragm cup 3 and the plastic housing 2 and is connected to the plastic housing 2 from the outside. Fig. 2 The part of the diaphragm pot 3 (the casing 9) which is not visible is Fig. 2 also not visible housing opening (4 in Fig. 3 , 4 , 5 ) of the plastic housing 2.

[0071] An internal structure of an area of ​​the ultrasonic sensor 1 in which the diaphragm pot 3 is inserted into the housing opening (4 in Fig. 3 , 4 , 5 ) is now being introduced, based on the Fig. 3-6 described. Fig. 3 shows a horizontal section AA of the view from Fig. 2 ; Fig. 4 shows a vertical section BB of the view from Fig. 3 : Fig. 5 shows a vertical section CC of the view from Fig. 3 ; and Fig. 6 shows a vertical section DD of the view from Fig. 3 . The directions x and y in Fig. 3-5 describe a first (x) and a second (y) radial direction. In particular, Fig. 3 The arrows marked x and y point radially outwards. The direction z in Fig. 3-5 denotes an axial direction (axial direction of the jacket 9 of the diaphragm cup 3 ( Fig. 2 ) and the axial direction of the housing opening 4 of the plastic housing 2). Specifically, the arrow marked z points axially outward. The axial outward direction is also referred to as the "upward" direction, and the axial inward direction is also referred to as the "downward" direction. The terms "up" and "downward," "above" and "below" refer to the drawing and are intended to represent the actual spatial orientation of the ultrasonic sensor 1 ( Fig. 2 ) in any way.

[0072] It will be Fig. 4-6 Reference is made to the drawing. The plastic housing 2 is open at the top and surrounds a substantially cylindrical inner housing opening 4, which extends axially inward or downward from a level of an upper or front edge 11 of the plastic housing 2. An axially inner section of the jacket 9 of the diaphragm cup 3 is arranged in the housing opening 4. A silicone ring 6 (example of a decoupling element) is arranged between the jacket section 9 and the inner surface 5 of the plastic housing 2.

[0073] An annular bracket 12 ( Fig. 4-6 ) forms a bottom section of the housing opening 4. Another bottom section 14 of the housing opening 4 runs imaginarily through the open central area, which is bordered by the annular bracket 10. The bracket 12 is formed integrally with the plastic housing 2. The inner surface 5 of the plastic housing thus also encompasses a surface of the bracket 12. Other components of the ultrasonic sensor 12, such as electronic components (not shown) for controlling a piezo element (not shown) attached to the underside of the ultrasonic membrane 8, and the like, are arranged in a housing interior 13 below the bracket 12. In other words, the "housing opening 4" refers to an opening or recess in the plastic housing 2 specifically provided for accommodating at least a portion of the membrane cup 3. However, the housing opening 4 does not necessarily encompass the entire interior 13 of the ultrasonic sensor 1.

[0074] As in Fig. 4-6 As shown, a plurality of first ribs 71 are arranged on the upper side of the bracket 12 - and thus on an inner surface 5 of the plastic housing 2. The first ribs 71 protrude outwards or upwards in the axial direction of the housing opening 4 and run annularly in a circumferential direction around the entire circumference of the housing opening 4. An end face 15 of the casing 9 of the diaphragm cup 3 is flange-shaped at its axially inner or lower end. In an area in which the end face 15 of the casing 9 of the diaphragm cup 3 and the upper side of the bracket 12, which defines a bottom section of the housing opening 4, overlap, a section of the silicone ring 6 is arranged between the end face 15 of the casing and the bracket 12. The first ribs 71 are also arranged in the same overlap area on the inner surface of the plastic housing 5 in the area of ​​the bracket 12.The silicone ring 6 (a horizontal section of the silicone ring 6) rests in this overlap area against the end face 15 of the casing 9 of the diaphragm cup 3. Thus, the energy of axial vibrations of the diaphragm cup 3 can be transferred into the silicone ring 6 and dissipated there through internal friction. In contrast, due to the first ribs 71 arranged on the surface of the bracket 12 in the overlap area, a portion of the inner surface 5 of the plastic housing that is in contact with the silicone ring 6 is reduced in the area of ​​the bracket 12 compared to a case where the first ribs 71 are not provided. Thus, during axial structural vibrations of the diaphragm cup 3, the silicone ring 6 is alternately compressed and relaxed in the overlap area of ​​the end face 15 of the casing 9 and the inner surface 5 of the plastic housing 2 on the top side of the bracket 12, and acoustic decoupling can be provided, i.e., the energy transfer from the ultrasonic membrane 3 to the console 12 and thus to the plastic housing 2 can be reduced.

[0075] A further vertical section of the silicone ring 6 is arranged in an overlap region between an outer surface 17 of the casing 9 of the diaphragm pot 3 and a casing section of the inner surface 5 of the plastic housing 2 in the region of a casing 21 of the housing opening 4 formed by the plastic housing 2.

[0076] Particular attention is paid to the AA section in Fig. 3 Reference is made. In the overlap area between the outer surface 17 of the casing 9 of the diaphragm pot 3 and the casing section of the inner surface 5 of the plastic housing 2, the silicone ring 6 lies continuously over its entire surface on the outer surface 17 of the casing 9 of the diaphragm pot 3 ( Fig. 4 ). Thus, the energy of radial vibrations of the diaphragm pot 3 can be transferred into the silicone ring 6 and dissipated there by internal friction. In contrast, a plurality of second ribs 72 are formed on the jacket section of the inner surface 5 of the plastic housing 2, which protrude radially inward. The contact between the silicone ring 6 and the plastic housing 2 is thus essentially reduced to the tips of the ribs 72; free cavities 16 are formed between the ribs 72, in which there is no contact between the silicone ring 6 and the inner surface 5 of the plastic housing 2. Accordingly, during radial structural vibrations of the diaphragm pot 3, the silicone ring 6 is alternately compressed and relaxed in the overlap region of the outer surface 17 of the jacket 9 and the jacket section of the inner surface 5 of the plastic housing 2, and acoustic decoupling can be provided, i.e., the energy transfer from the ultrasonic membrane 3 to the plastic housing 2 can be reduced.

[0077] In the cut CC, which is in Fig. 5 shown, it can be seen that the second rib 72 shown there extends in the axial direction over the entire overlap area from the outer surface (17 in Fig. 3 ) of the jacket 9 of the diaphragm pot 3 with the jacket section of the inner surface 5 of the plastic housing 2 in the area of ​​the jacket 21. Furthermore, in Fig. 5 It can be seen that the axially extending rib 72 forms an insertion bevel. The insertion bevel can serve to simplify the insertion of the diaphragm cup 3 with the attached silicone ring 6 into the housing opening 4. Particularly when the diaphragm cup 3 is mounted under a defined preload, the insertion bevel can also be used to specify the desired position of the diaphragm cup 3.

[0078] In the cut DD, which is in Fig. 6 As shown, a cavity 16 is provided by way of example between two of the second ribs (72 in Fig. 3 , 5 ) can be recognized. In other words, in sections between two second ribs (72 in Fig. 3 , 5 ) no contact between the silicone ring 6 and the jacket section of the inner surface 5 of the plastic housing 2 in the area of ​​the jacket 21.

[0079] Further with reference to Fig. 4-6 An annular cover 10 is placed externally onto the diaphragm cup 3 and the plastic housing 2. The annular cover 10 is a two-component material with a hard component 18 and a soft component 19. The hard component 18 of the cover 10 is laser-welded externally to the wall 15 of the plastic housing 2. The soft component 19 of the cover rests against and covers the front edge 11 of the plastic housing 2 (the casing 21), the silicone ring 6, and the outer surface 17 of the casing 9 of the diaphragm assembly 3. The cover serves to fix and seal the connection between the diaphragm cup 3 and the plastic housing 2. Only the soft component 19 of the cover 10 rests against those components, namely the diaphragm cup 3 and the silicone ring 6, for which structural vibrations are permitted according to the proposed structure. The soft component 19 of the cover 10 can also be silicone.Accordingly, hardly any vibration energy is transferred through the cover 10 to the plastic housing 2.

[0080] Fig. 7 shows a schematic plan view of a motor vehicle 20 according to a third exemplary embodiment. The motor vehicle has an ultrasonic sensor 1, which may be an ultrasonic sensor according to the first or second exemplary embodiment. The ultrasonic sensor 1 is installed on the side of the motor vehicle 20 and is used by a control unit (not shown) of the motor vehicle 20, which forms a parking assistance system, to measure the surroundings to the side of the motor vehicle.

[0081] Although the present invention has been described using exemplary embodiments, it can be modified in many ways.

[0082] So in Fig. 3 An anisotropic structure is shown in which the second ribs 72 are arranged only in a region that runs essentially in the second radial direction y. The shell 9 of the diaphragm cup 3 is elliptical, and accordingly, the ultrasonic diaphragm 8 is also elliptical. Fig. 3 The structure shown is essentially designed to dampen and acoustically decouple radial vibrations of the diaphragm pot 3 in the second radial direction y. Fig. 3 The structure shown is specifically tailored to the radiation characteristics of a specific ultrasonic membrane 8. However, it is of course also conceivable to provide the ribs 72 at other sections or along the entire circumference of the inner wall 5 of the plastic housing 2 if other or any radial vibrations in the first and / or second radial direction or in any linear combination thereof are to be decoupled.

[0083] The Fig. 7 The arrangement of the ultrasonic sensor 1 on the motor vehicle 20 shown is purely exemplary. It is understood that in practical embodiments, a plurality of proposed ultrasonic sensors 1 can be arranged around an outer skin of the vehicle 20 in order to reliably monitor the entire surroundings of the motor vehicle 20.

[0084] Based on the exemplary embodiments, structures of an ultrasonic sensor 1 were described in which particularly good acoustic decoupling between the diaphragm assembly 3 and the plastic housing 2 is provided by a reduced portion of an inner surface 5 of the plastic housing 2, which is in contact with a side of the decoupling element 6 facing away from the diaphragm assembly 3. The acoustic decoupling is thus shifted further outward, i.e., away from the diaphragm cup 3, compared to comparative examples in which no ribs are formed in the plastic housing or only ribs are formed on the decoupling element 6. The diaphragm assembly 3 can also be mounted under prestress while maintaining the reduced load-bearing portion.This results in a clearly defined separation of the technical effect of acoustic decoupling (on the outer surface of the decoupling element 6) on the one hand and the technical effect of acoustic damping (inside the decoupling element 6) on the other. The proposed ultrasonic sensors 1 can therefore exhibit improved structural dynamics. LIST OF REFERENCE SYMBOLS

[0085] 1Ultrasonic sensor 2Plastic housing 3Membrane assembly, diaphragm cup 4Housing opening 5Inner surface of the housing opening 6Decoupling element, silicone ring 7Ribs 8Base, ultrasonic diaphragm 9Jacket 10Annular cover 11Front edge of the plastic housing 12Bracket, bottom section of the housing opening 13Housing interior 14Further bottom section of the housing opening 15Front side of the jacket of the diaphragm cup 16Cavity 17Outer surface of the jacket of the diaphragm cup 18Hard component 19Soft component 20Motor vehicle 21Jacket of the housing opening 71First ribs 72Second ribs

Claims

1. Ultrasonic sensor (1) for a motor vehicle (20), wherein the ultrasonic sensor (1) has: a plastics housing (2), a diaphragm assembly (3), which is arranged in a housing opening (4) of the plastics housing (4) and comprises an ultrasonic diaphragm (8), and a decoupling element (6), which is arranged between an inner surface (5) of the plastics housing (2) and the diaphragm assembly (3), wherein a plurality of ribs (7, 71, 72) against which the decoupling element (6) rests are formed on the inner surface (5) of the plastics housing (2), and the ribs (7, 71, 72) are formed such that the decoupling element (6) does not rest over all of its surface area against the inner surface (5) of the plastics housing (2), wherein the diaphragm assembly comprises a diaphragm pot (3) with a base (8) forming the ultrasonic diaphragm (8), and a jacket (9) formed in one piece with the base (8), wherein the diaphragm pot (3) is inserted in the housing opening (4) along an axial direction of the housing opening, characterized in that at least some of the ribs (72) on a jacket section of the inner surface (5) of the plastics housing (2) project radially inwards and extend in the axial direction of the housing opening (4).

2. Ultrasonic sensor according to Claim 1, wherein the decoupling element (6) rests over all of its surface area against the diaphragm assembly (3).

3. Ultrasonic sensor according to either of the preceding claims, wherein the diaphragm assembly (3) is mounted under preloading in the housing opening (4).

4. Ultrasonic sensor according to one of Claims 1 to 3, wherein at least one section of the decoupling element (6) is arranged in an entire first overlap region, in which an outer surface (17) of the jacket (9) of the diaphragm pot (3) and the jacket section of the inner surface (5) of the plastics housing (2) overlap, lies flat against the jacket (9) of the diaphragm pot (3), and annularly encloses the jacket (9) of the diaphragm pot (3), wherein the ribs (72) extending in the axial direction are formed in the jacket section of the inner surface (5) of the plastics housing (2) in the first overlap region.

5. Ultrasonic sensor according to Claim 4, wherein the ribs (72) extending in the axial direction form an insertion bevel for inserting the diaphragm pot (3) and the decoupling element (6).

6. Ultrasonic sensor according to one of Claims 1 to 5, wherein at least some of the ribs (71) on a base portion (12) of the housing opening (4) project in the axial direction of the housing opening (4) and extend annularly in a circumferential direction of the housing opening (4) .

7. Ultrasonic sensor according to Claim 6, wherein the base portion of the housing opening (4) is formed by an annular bracket (12) which is formed in one piece with the plastics housing (2), lies on the inside in the axial direction, and projects radially inwards.

8. Ultrasonic sensor according to Claim 6 or 7, wherein at least one section of the decoupling element (6) is arranged in an entire second overlap region, in which an end face (15) of the jacket (9) of the diaphragm pot (3) and the base section (12) of the housing opening (4) overlap, and lies flat against the end face (11) of the jacket (9) of the diaphragm pot (3), wherein the ribs (71) extending annularly in the radial direction are formed on the base section (12) of the housing opening (4) in the second overlap region.

9. Ultrasonic sensor according to one of Claims 1 to 8, wherein an annular lid (10) is placed on the diaphragm pot (3) and the plastics housing (2) from the outside, covers exposed sections of the decoupling element (6), and is connected to the plastics housing (2) from the outside, wherein the annular lid (10) is a two-component material with a hard material component (18) and a soft material component (19), and the soft material component (19) rests against the outer surface (17) of the jacket (9) of the diaphragm pot (3), against the exposed sections of the decoupling element (6), and against an end-face edge (11) of the plastics housing (2).

10. Motor vehicle (20) with at least one ultrasonic sensor (1) according to one of Claims 1 to 9.