Ultrasonic sensor and vehicle

Abstract

The present invention relates to an ultrasonic sensor (5) and a vehicle, wherein the ultrasonic sensor (5) has: a housing (10), a membrane cup (20), and a piezoelectric transducer (30), wherein the membrane cup (20) has a substantially cylindrical wall (22) and a vibratable membrane (25) and is formed from a polymer, wherein the piezoelectric transducer (30) is integrated into the membrane (25) in that the piezoelectric transducer (30) is completely covered by the polymer of the membrane (25), and wherein the membrane cup (20) is at least partially inserted into the housing (10) and attached to the housing (10).

Description

[0001] Description

[0002] title

[0003] Ultrasonic sensor and

[0004] State of the art

[0005] The present invention relates to an ultrasonic sensor and a vehicle with such an ultrasonic sensor.

[0006] Ultrasonic sensors are known from the state of the art. Their measuring principle is based on the transmission and reception of acoustic waves. These waves are emitted in the inaudible range by means of a vibrating membrane, often made of aluminum, and can be reflected back to the ultrasonic sensors by objects in the vicinity.

[0007] Acoustic waves reflected in this way can be received by the membrane and converted into an electrical signal by means of a transducer, on the basis of which a propagation time measurement of the signal can be carried out to determine distances to objects in the vicinity of the ultrasonic sensors.

[0008] In connection with the use of ultrasonic sensors as environment sensors in vehicles, a coating facing the environment is often applied to the membranes of the ultrasonic sensors in order to integrate them as inconspicuously as possible into bumpers and / or deviating arrangement areas of vehicles by appropriately matching the color of the coating.

[0009] It is also known to use a polymer instead of aluminum for the manufacture of ultrasonic sensors, whereby the use of polymers can also refer to the design of the membrane itself. DE102017216868A1 discloses a sound transducer, in particular for an ultrasonic transducer, comprising a housing, a decoupling element, a membrane cup, and an electroacoustic transducer element. At least the membrane cup and a part of the housing are formed from a plastic material. The decoupling element is integrated into the membrane cup, in particular into the wall of the membrane cup and / or the at least part of the housing.

[0010] DE102015115419 A1 discloses an ultrasonic sensor for a motor vehicle with a membrane having a membrane base and a membrane shell wall, wherein the membrane base has a front side pointing in the transmission direction of the ultrasonic sensor emitting an ultrasonic signal and a rear side opposite the front side.

[0011] Disclosure of the invention

[0012] According to a first aspect of the present invention, an ultrasonic sensor and in particular an ultrasonic sensor for a vehicle is proposed, which comprises a housing, a diaphragm pot, and a piezoelectric transducer.

[0013] The diaphragm cup has a substantially cylindrical wall and a vibrating diaphragm and is formed from a polymer (e.g., polyamide, epoxy, etc.), which can advantageously be a fiber-reinforced polymer (e.g., using carbon fiber, glass fiber, etc.), without being limited thereto. The term "substantially cylindrical wall" is explicitly understood to include diaphragm cup designs in which the diaphragm cup has a flange and / or reinforcing elements and / or fastening elements and / or depressions and / or elevations and / or a certain inclination and / or extension and / or deformation of the outer surface, etc.

[0014] It is also advantageous if the diaphragm pot is formed in one piece, for example as an injection-molded part.

[0015] The piezoelectric transducer, which is preferably disc-shaped, is integrated into the diaphragm in that the piezoelectric transducer is completely covered by the polymer of the diaphragm. In the advantageous case in which the diaphragm cup is formed as an injection-molded part, the piezoelectric transducer can be embedded directly into the diaphragm during the injection-molding process. This offers the advantage, among other things, that the diaphragm cup, including the piezoelectric transducer, can be formed in a single production step, which can reduce production costs and / or material costs, for example. Furthermore, enclosing the piezoelectric transducer on all sides by the polymer of the diaphragm has the advantage of creating a particularly reliable connection between the diaphragm and the piezoelectric transducer.

[0016] Furthermore, the diaphragm cup is at least partially inserted into the housing and fastened to the housing. Fastening to the housing is preferably effected indirectly via a decoupling element configured to provide at least partial mechanical decoupling between the housing and the diaphragm cup, for example, to keep vibrations acting on the ultrasonic sensor away from the piezoelectric transducer as far as possible, thus ensuring the most trouble-free operation of the ultrasonic sensor. This does not preclude the diaphragm cup from being connected directly to the housing without such a decoupling element.

[0017] The decoupling element is designed, for example, as a silicone ring which is arranged on and / or integrated into a fastening element to be connected to the housing and which fixes the diaphragm pot within the housing in the assembled state of the ultrasonic sensor.

[0018] The subclaims show preferred developments of the invention.

[0019] In an advantageous embodiment of the present invention, the covering of the piezoelectric transducer by the polymer of the membrane provides that the piezoelectric transducer is covered on one or both sides in the direction of a main receiving axis or a main transmitting axis (i.e., a direction which is generally perpendicular to the membrane surface) with a polymer layer whose thickness corresponds to a quarter or an odd multiple of a quarter of a wavelength of a desired resonant frequency of the ultrasonic sensor. In this way, a resonance effect can be achieved by means of which a signal to be transmitted and / or received can be correspondingly amplified in the range of the resonant frequency. Particularly advantageously, a polymer layer with such a thickness is provided both on a side of the membrane facing the environment and on a side facing the interior of the housing of the ultrasonic sensor.This does not explicitly exclude the possibility that only the side of the membrane facing the environment or only the side facing the interior of the housing has such a thickness, while the other side has a different thickness, for example to achieve a different resonance behavior of the ultrasonic sensor.

[0020] Particularly advantageously, the membrane has a coating with a thickness of up to 300 pm, preferably up to 200 pm and particularly preferably up to 70 pm on a side which faces the surroundings of the ultrasonic sensor. The coating is, for example, a paint and / or powder coating and can be used, among other things, for optically adapting the outwardly visible membrane surface (e.g. matched to a color of an installation area of ​​the ultrasonic sensor on a vehicle) and / or for mechanically protecting the membrane and / or for specifically adapting a modulus of elasticity of the membrane. By adapting the modulus of elasticity, the resonance frequency of the ultrasonic sensor can be influenced, for example.The use of a polymer membrane also offers the unique advantage that any necessary corrosion protection and / or passivation of the membrane surface is eliminated, as the membrane is not made of aluminum or a comparable metal. This means that the coating thickness can be thinner than that of conventional aluminum membranes, resulting in material and cost savings, as well as greater flexibility in determining the coating thickness, which, among other things, results in greater flexibility in determining the resonance behavior of the ultrasonic sensor.

[0021] In a particularly advantageous embodiment of the present invention, electrical contact with the piezoelectric transducer is made via a first electrical conductor and a second electrical conductor, which are guided at least partially through the polymer of the diaphragm cup to a first electrical contact and a second electrical contact, which are exposed on the diaphragm cup for electrical contact with the housing, wherein the electrical contact of the housing is preferably provided for forwarding electrical transmission and / or reception signals between the piezoelectric transducer and an electrical circuit arranged in the housing, which is configured to generate the transmission signals and / or process the reception signals. The first electrical conductor and / or the second electrical conductor are designed, for example, as insulated or uninsulated wires or deviating therefrom.In a preferred case in which the polymer used to form the diaphragm cup is an electrically non-conductive polymer, the electrical contact can be formed particularly easily and cost-effectively by means of the first and second electrical conductors, since these do not have to be insulated from a conductive base material of the diaphragm cup used in the prior art (e.g., aluminum) in order to prevent a short circuit. A further advantage arises from the fact that the two electrical conductors are particularly insensitive to mechanical stress when guided at least partially through the polymer and / or on a surface of the polymer of the diaphragm cup. Particularly preferably, the first and second electrical conductors are directly integrated, analogous to the piezoelectric element, in a single injection molding process to form the diaphragm cup and / or the diaphragm.The first electrical contact and / or the second electrical contact are, for example, sections of the first conductor and / or the second conductor itself and / or additional contact elements (e.g., contact surfaces or contact pads) that are formed separately from the first and / or second electrical conductor and electrically connected to the first and / or second electrical conductor. These contacts can also be formed, for example, in the aforementioned individual injection molding process.

[0022] Advantageously, the first electrical contact and / or the second electrical contact are arranged on an inner surface of the diaphragm cup wall and / or on an outer surface of the diaphragm cup wall and / or on an end face of the diaphragm cup facing the housing interior, without thereby restricting the arrangement position of the first contact and / or the second contact on the diaphragm cup. Accordingly, it is also possible, for example, to arrange the first contact on the inner surface of the diaphragm cup wall and the second contact on the outer surface of the diaphragm cup, and in combinations of respective arrangement positions that deviate from these.

[0023] Preferably, the first electrical contact and the second electrical contact of the diaphragm cup are contacted with the housing via housing contacts provided on the housing and corresponding to an arrangement position of the first contact and the second contact. Such electrical contact between the diaphragm cup and the housing is advantageously established implicitly during assembly of the ultrasonic sensor when the diaphragm cup is attached to the housing, thereby significantly shortening the manufacturing process compared to the prior art, since the prior art typically requires a soldering process to connect wires electrically connected to the piezoelectric transducer to corresponding contacts of the housing.

[0024] In a further advantageous embodiment of the present invention, contact is made between the first electrical contact and the second electrical contact of the diaphragm cup and the housing via an at least partially electrically conductive decoupling element, via which the diaphragm cup and the housing are at least partially mechanically decoupled in the assembled state. This decoupling element is preferably the decoupling element described above (or a decoupling element deviating therefrom) in an embodiment in which the decoupling element has separate electrically conductive sections configured to separately connect the two lines of the piezoelectric transducer to the housing.The electrically conductive sections are formed, for example, by means of an electrically conductive coating on the decoupling element and / or by means of a wire integrated into the decoupling element and / or arranged on its surface and / or in a manner deviating therefrom.

[0025] Advantageously, the electrical contact between the diaphragm cup and the housing is established via spring contacts (e.g., as pogo pins, etc.) and / or soldered connections and / or welded connections. According to a second aspect of the present invention, a vehicle is proposed which has at least one ultrasonic sensor according to one of the preceding claims. The vehicle is preferably designed as a road vehicle (e.g., as a car, van, truck, bus, motorcycle, etc.), as a rail vehicle, or deviating therefrom. Particularly advantageously, the vehicle has a plurality of such ultrasonic sensors, which are provided, for example, for detecting the surroundings of the vehicle. Such surroundings detection is used, for example, for a (partially) automated driving system of the vehicle and / or for a driver assistance system of the vehicle.The features, combinations of features and the advantages resulting from them correspond to those explained in connection with the first-mentioned aspect of the invention in such a way that, in order to avoid repetition, reference is made to the above explanations.

[0026] Short description of the drawings

[0027] Embodiments of the invention are described in detail below with reference to the accompanying drawings. In the drawing:

[0028] Figure 1 is a schematic view of an exemplary embodiment of an ultrasonic sensor according to the invention;

[0029] Figure 2 is a schematic view of an exemplary embodiment of a diaphragm pot according to the invention;

[0030] Figure 3 is a schematic view of another exemplary embodiment of a diaphragm pot according to the invention;

[0031] Figure 4 is a schematic view of another exemplary embodiment of a diaphragm pot according to the invention; and

[0032] Figure 5 is a schematic view of an exemplary embodiment of a vehicle according to the invention.

[0033] Embodiments of the Invention Figure 1 shows a schematic view of an exemplary embodiment of an ultrasonic sensor 5 according to the invention, which comprises a housing 10 made of a polymer, a diaphragm cup 20 also made of a polymer, a piezoelectric transducer 30, and a fastening element 90, which is also made of a polymer. The individual components are shown here in a separated state (in a partially exploded view) for clarity.

[0034] The ultrasonic sensor 5 is designed here as an example as an ultrasonic sensor 5 for a passenger car.

[0035] The diaphragm cup 20 has a substantially cylindrical wall 22 and a vibrating diaphragm 25 and is formed in one piece by an injection molding process. During the manufacture of the diaphragm cup 20, the piezoelectric transducer 30 is integrated into the diaphragm 25 during the injection molding of the diaphragm cup 20, so that the piezoelectric transducer 30 is covered on both sides by a polymer layer 40 of the diaphragm 25.

[0036] During the manufacture of the ultrasonic sensor 5, the diaphragm cup 20 is inserted into the housing 10 with an end face 27 facing forward and is fastened to the housing 10 by means of the fastening element 90. For mechanical decoupling of the diaphragm cup 20 from the housing 10, a decoupling element 80 designed as a silicone ring is provided on the fastening element 90.

[0037] Furthermore, the one surface of the membrane 25 facing the environment has a coating 50, which here has a thickness of 70 pm.

[0038] Figure 2 shows a schematic view of an exemplary embodiment of a diaphragm cup 20 according to the invention. Due to numerous similarities between the diaphragm cup 20 shown in Figure 1 and the diaphragm cup 20 shown in Figure 2, only the differences between these figures are described below to avoid repetition.

[0039] The diaphragm cup 20 in Figure 2 has a first electrical conductor 60 formed as a wire, which is guided through the polymer of the diaphragm cup 20 to a first electrical contact 70 (here a contact pad) on the end face 27 of the diaphragm cup 20 and electrically connects a first terminal (not shown) of the piezoelectric transducer 30 to the first electrical contact 70.

[0040] In addition, the diaphragm cup 20 in Figure 2 has a second electrical conductor 65 designed as a wire, which is guided through the polymer of the diaphragm cup 20 to a second electrical contact 75 (here also a contact pad) on the end face 27 of the diaphragm cup 20 and electrically connects a second terminal (not shown) of the piezoelectric transducer 30 to the second electrical contact 75.

[0041] The first electrical contact 70 and the second electrical contact 75 of the diaphragm cup 20 are connected to the housing 10 (see Figure 1) via housing contacts provided on the housing 10, which correspond to an arrangement position of the first contact 70 and the second contact 75. The housing contacts are designed, for example, as spring contacts to ensure a reliable electrical connection.

[0042] Figure 3 shows a schematic view of another exemplary embodiment of a diaphragm cup 20 according to the invention, which differs from the diaphragm cup 20 shown in Figure 2 only in that the electrical contacts 70, 75 of the diaphragm cup 20 in Figure 3 are arranged on an inner surface of the wall 22. Since the further structure of the diaphragm cup 20 shown in Figure 3 is otherwise identical to that in Figure 2, reference is made to the description of Figure 2 to avoid repetition.

[0043] Figure 4 shows a schematic view of a further exemplary embodiment of a diaphragm pot 20 according to the invention, wherein the electrical conductors 60, 65 and the electrical contacts 70, 75 of the diaphragm pot 20 are not shown here for better clarity.

[0044] From Figure 4 it can be seen that a polymer layer 40 of the membrane 25 facing the surroundings of the membrane pot 20, which polymer layer surrounds the piezoelectric transducer 30 on one side, has a thickness d1 which corresponds to a quarter of a wavelength of a desired resonance frequency of an ultrasonic sensor 5 (see e.g. Figure 1) in which the membrane pot 20 is arranged.

[0045] In addition, it can be seen that a polymer layer 40 of the membrane 25, which surrounds the piezoelectric transducer 30 on a side opposite the above-mentioned side, has a thickness d2 which also corresponds to a quarter of the wavelength of the desired resonance frequency of the ultrasonic sensor 5 (see, for example, Figure 1) in which the membrane pot 20 is arranged.

[0046] Based on the selected thicknesses d1 and d2, an advantageous amplification of the transmitted and received signals of the ultrasonic sensor 5 can be achieved in the range of its resonance frequency.

[0047] Figure 5 shows a schematic view of an exemplary embodiment of a vehicle 100 according to the invention, which is designed here as a passenger car and has an environment detection system 110 which is connected in terms of information technology to a plurality of ultrasonic sensors 5 according to the invention in order to implement a function of a driver assistance system (e.g. a parking aid) based on the ultrasonic sensors 5.

Claims

Claims 1 . Ultrasonic sensor (5) comprising: a housing (10), a diaphragm cup (20), and a piezoelectric transducer (30), wherein the diaphragm cup (20) has a substantially cylindrical wall (22) and an oscillatable diaphragm (25) and is formed on the basis of a polymer, the piezoelectric transducer (30) is integrated into the diaphragm (25) by the piezoelectric transducer (30) being completely covered by the polymer of the diaphragm (25), and the diaphragm cup (20) is at least partially inserted into the housing (10) and fastened to the housing (10).

2. Ultrasonic sensor (5) according to claim 1, wherein the diaphragm pot (20) is manufactured by means of an injection molding process in which the piezoelectric transducer (30) is integrated into the diaphragm (25), and / or the polymer of the diaphragm pot (20) is a fiber-reinforced polymer.

3. Ultrasonic sensor (5) according to one of the preceding claims, wherein the covering of the piezoelectric transducer (30) by the polymer of the membrane (25) provides that the piezoelectric transducer (30) is covered on one side or both sides in the direction of a main receiving axis or a main transmitting axis with a polymer layer (40), the thickness (d1, d2) of which corresponds to a quarter or an odd multiple of a quarter of a wavelength of a desired resonance frequency of the ultrasonic sensor (5).

4. Ultrasonic sensor (5) according to one of the preceding claims, wherein the membrane (25) on a side which is exposed to an environment of the ultrasonic sensor (5) facing, has a coating (50) with a thickness of up to 300 pm, preferably up to 200 pm and particularly preferably up to 70 pm.

5. Ultrasonic sensor (5) according to one of the preceding claims, wherein electrical contacting of the piezoelectric transducer (30) takes place via a first electrical conductor (60) and a second electrical conductor (65), which are guided at least partially through the polymer of the diaphragm pot (20) to a first electrical contact (70) and a second electrical contact (75), which are exposed on the diaphragm pot (20) for electrical contacting with the housing (10).

6. Ultrasonic sensor (5) according to claim 5, wherein the first electrical contact (70) and / or the second electrical contact (75) is arranged on a inner surface of the wall (22) of the diaphragm pot (20), and / or outer surface of the wall (22) of the diaphragm pot (20), and / or end face (27) of the diaphragm pot (22) facing the inside of the housing.

7. Ultrasonic sensor (5) according to claim 5 or 6, wherein contacting of the first electrical contact (70) and the second electrical contact (75) of the diaphragm cup (20) with the housing (10) is effected via housing contacts provided on the housing (10) and corresponding to an arrangement position of the first contact (70) and the second contact (75).

8. Ultrasonic sensor (5) according to one of claims 5 to 7, wherein contacting of the first electrical contact (70) and the second electrical contact (75) of the diaphragm cup (20) with the housing (10) takes place via an at least partially electrically conductive decoupling element (80), via which the diaphragm cup (20) and the housing (10) are at least partially mechanically decoupled in the assembled state.

9. Ultrasonic sensor (5) according to one of claims 5 to 8, wherein the electrical contact between the membrane pot (20) and the housing (10) is made via spring contacts and / or soldered connections and / or welded connections.

10. Vehicle (100) comprising at least one ultrasonic sensor (5) according to one of the preceding claims.

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