Acoustic sensor housing for mounting on a vehicle, and vehicle comprising one or more acoustic sensor housings

Abstract

Acoustic sensor housing (10) for arrangement on a vehicle, wherein at least one printed circuit board (14) comprising at least one printed circuit board opening (14a) open on one side for sound entry is arranged in an interior (12) of the acoustic sensor housing (10) and an acoustic sensor (15) is mounted on the at least one printed circuit board opening (14a), wherein the acoustic sensor housing (10) is closed and at least one housing section (10a) of the acoustic sensor housing (10) opposite the open side of the at least one printed circuit board opening (14a) is made of a material with low acoustic impedance.

Description

[0001] The invention relates to an acoustic sensor housing for arrangement on a vehicle and a vehicle comprising one or more such acoustic sensor housings.

[0002] The following definitions apply to the entire disclosure content.

[0003] Acoustic sensors for detecting external noises outside of vehicles are known in the prior art. For example, DE 10 2016 006 802 A1 discloses a method and a device for detecting at least one special signal emanating from an emergency vehicle.

[0004] Fundamental aeroacoustic research has shown that the turbulence and fluctuations generated by flow around bodies produce flow noise. This noise depends on the inflow velocity, the turbulence intensity of the flow, and the geometry of the body. A sharply tapered trailing edge and a large leading-edge radius are known to generate relatively low flow noise.

[0005] When objects move in still air, the movement creates a relative flow velocity between the stationary air fluid and the moving object. At the edges and contours of the object, the flow interacts with the object itself. This leads to deflections and separation of the flow, resulting in velocity fields and turbulence, i.e., vortex formation. These dynamic velocity changes and the formation of turbulence, in turn, generate aeroacoustic noise. The intensity of the resulting aeroacoustic noise increases with the relative flow velocity and the strength of the turbulence.

[0006] Aeroacoustic noise is an undesirable source of interference for acoustic sensors mounted externally on the vehicle and thus exposed to airflow, as it reduces the signal-to-noise ratio of the acoustic sensor. Therefore, when installing acoustic sensors externally on the vehicle, care is taken to select sensor positions where the relative airflow velocity is as low as possible when the vehicle is in motion.

[0007] Acoustic sensors in automobiles are typically installed at the front of the vehicle, facing directly in the direction of travel. This creates a dynamic pressure in front of the sensor, resulting in a low airflow velocity and therefore low wind noise emissions directly at the acoustic sensor. Consequently, the acoustic sensor is only minimally affected by wind noise.

[0008] Behind the vehicle, a different effect is typically used to obtain audio recordings with minimal wind noise. This relies on the fact that a low-speed area is created behind the vehicle in its "wind shadow": the trailing edges are then located higher up on the vehicle. If the acoustic sensors are placed, for example, at the bottom of the bumper, they are far from the trailing edge and are therefore only minimally affected by wind noise.

[0009] With a truck and trailer, microphones intended to listen to the rear of the vehicle present a problem: the "wind shadow" only forms at the very back of the trailer. Mounting acoustic sensors on the trailer is not desirable, as this would require wiring between the trailer and the tractor unit. Mounting them behind the tractor unit, i.e., between the tractor unit and the trailer, is also undesirable due to the high levels of engine noise in that area. Microphones facing forward can be positioned similarly to those used in cars. Wind noise is most pronounced on the sides of the vehicle and on the roof, making it ineffective to mount a sensor pointing sideways or upwards in these locations.

[0010] DE 10 2022 209 934 A1 discloses a flow-noise-reduced acoustic sensor housing for acoustic sensors facing against the direction of travel, intended for the exterior of a vehicle. A disadvantage of the disclosed solution is that the acoustic sensor housing includes one or more openings for directing airborne sound to the acoustic sensors. Moisture and dirt particles can penetrate the interior of the acoustic sensor housing through these openings, and thus also enter the acoustic sensor itself, for example, the transducer of a microphone, thereby impairing the transmission characteristics of the acoustic sensor, such as the microphone transducer, including amplitude, frequency, or phase response.

[0011] A generic acoustic sensor housing is disclosed in DE 10 2019 206 331 A1. Further prior art is disclosed, for example, in CN 000 116 033 310 A.

[0012] Previously known acoustic sensor housings always have at least one opening through which the airborne sound waves can reach the acoustic sensor and excite it.

[0013] This is where the invention comes in. The object of the invention was to provide an acoustic sensor housing that optimizes the transmission behavior of an acoustic sensor and further minimizes airflow to suppress background noise.

[0014] The subject matter of the independent and dependent claims each solve this problem. Further developments and advantageous embodiments are described in the dependent claims, the drawings, and the description of preferred embodiments.

[0015] The invention relates to a generic acoustic sensor housing for installation on a vehicle, wherein at least one printed circuit board is arranged in an interior space of the acoustic sensor housing. The printed circuit board comprises at least one opening open on one side for sound ingress. An acoustic sensor is mounted onto the at least one opening of the printed circuit board, meaning that at this end the opening is closed on one side by the mounted acoustic sensor.

[0016] An acoustic sensor is a sensor that detects mechanical vibrations, for example, those caused by sound waves in the air, and converts them into a processable signal, such as an electrical signal like a voltage. The acoustic sensor includes an analog and / or digital signal output. The conversion takes place in two stages. In the first acoustic-mechanical conversion stage, the sound waves are converted into the movement of an object according to a specific receiver principle. In the second mechanical-electrical conversion stage, the object's movement is converted into the electrical signal according to a specific transducer principle. Examples of acoustic sensors include arrangements of a magnet and an electrical coil, microphones, accelerometers, piezoelectric transducers, and strain gauges.A micro-electro-mechanical system, abbreviated MEMS, comprising an array of semiconductor elements that detect vibrations, can also be used as an acoustic sensor. The acoustic sensor can, for example, be a microphone. The microphone can include a microphone capsule for acoustic-mechanical conversion and a transducer for mechanical-electrical conversion. The microphone is, for example, designed as a MEMS microphone. MEMS microphones are miniaturized microphones, often manufactured using surface-mount technology (SMD) for direct mounting on printed circuit boards. MEMS microphones are small and easy to process industrially; for example, they can be mounted using a reflow soldering process. Compared to other microphones, MEMS microphones are less sensitive to high temperatures and are therefore particularly well-suited for automotive applications.

[0017] The circuit board may include additional components, such as logic devices like ASICs or FPGAs, to implement functions such as high-pass filters and / or compressors required to limit the dynamic range of the signal. These components and their connections serve to preprocess analog or digital signals from the acoustic sensor. The components are designed for analog or digital signal processing and / or for implementing filter functions, phase inversion functions, compressor functions, and / or amplifier functions. Furthermore, the circuit board may have a connector for connecting the acoustic sensor to an electronic control unit. This control unit is designed to locate and / or classify sound sources based on the signals from the acoustic sensor.The components and / or acoustic sensors are, for example, mounted directly on the surface of the circuit board, for example soldered, and are also called surface mounted devices, abbreviated SMD.

[0018] In solving the problem, it was surprisingly discovered that a closed housing design optimizes the transmission behavior of the acoustic sensor. Because the housing is closed, no moisture or dirt particles can penetrate it.

[0019] The invention proposes that the acoustic sensor housing is closed and that at least one housing section of the acoustic sensor housing opposite the open side of the at least one circuit board opening is made of a material with low acoustic impedance.

[0020] Acoustic impedance is a physical quantity that describes a medium's resistance to the propagation of sound waves. It can be defined as the product of the medium's density and the speed of sound within that medium. These properties result in the material offering less resistance to the propagation of sound waves. When sound travels from one medium to another, the ratio of the acoustic impedances of the two media determines the proportion of sound that is reflected and the proportion that is transmitted. The material is chosen such that the proportion of sound that is transmitted is greater than the proportion that is reflected.

[0021] Due to its low acoustic impedance, this housing section ensures low acoustic damping, particularly low sound attenuation. When airborne sound waves strike the housing section's material, it begins to vibrate, thus transmitting the sound waves into the acoustic sensor housing through the circuit board opening and onto the sensor itself. The material therefore acts as an acoustically permeable membrane. At the same time, the acoustic sensor housing is sealed, meaning it has no openings. This prevents moisture or dirt particles from entering the housing, thereby optimizing the acoustic sensor's transmission characteristics.

[0022] Another aspect is that the material of the aforementioned housing section is selected from polymers, preferably synthetic polymers. Polymers exhibit a low acoustic impedance relative to other chemical substances. In an initial practical prototype, the synthetic polymer nylon polyamide 12 proved to be technically suitable.

[0023] According to another aspect, the housing section is tapered, preferably to a material thickness of less than 5 mm, and particularly preferably to a material thickness of 1.5 mm. Tapered means that a material transitions from a wider to a narrower cross-section. According to one aspect, the housing section comprises polyamide 12 and is tapered to a material thickness of 1.5 mm. It has been shown that the acoustic sensor in such an acoustic sensor housing can acoustically perceive the environment, surprisingly, even in a closed acoustic sensor housing.

[0024] Another aspect is that the housing section described so far is decoupled from the rest of the acoustic sensor housing by a seal. A rubber seal or rubber lip, for example, can serve as the sealing component. The seals can be elastic and can provide defined decoupling of structure-borne noise. Another aspect is that the seal is softer than the housing section it encloses. The seals can, for example, be made of a softer material than the material of the enclosed housing section. The seals can have a wave-like or S-shaped form to allow for relatively easy bending.

[0025] Another aspect is that the circuit board is coupled to the acoustic sensor housing using sealing components. This also decouples the circuit board from structure-borne noise.

[0026] Another aspect is that further housing sections of the acoustic sensor housing comprise plastic or metal foams, rubber granules, or expanded glass granules. Plastic or metal foams, rubber granules, or expanded glass granules are examples of porous materials. The pore size determines the linear flow resistance and the surface roughness. The porous materials reduce trailing-edge sound radiation and thus improve the noise reduction effect. This is advantageous when the acoustic sensor housing is mounted onto an existing vehicle contour because it allows the air to flow past the acoustic sensor housing in an optimized manner, without creating a separation edge and the resulting turbulence, which in turn leads to high wind noise.

[0027] The edge of the acoustic sensor housing has the shape of a profile. The housing section is positioned within a region of the profile's trailing edge. The acoustic sensor housing can be mounted onto a vehicle contour. From one perspective, the housing section is tapered as described above.

[0028] The airfoil refers to the shape of a body's cross-section in the direction of airflow. When a vehicle moves through the air, the airflow is fluidized. As the airflow passes over the airfoil, a boundary layer forms. Depending on the flow velocity, angle of attack, airfoil shape, airfoil dimensions, and surface roughness, this boundary layer can be laminar or turbulent. At the trailing edge of the airfoil, this boundary layer interacts with the edge, resulting in trailing-edge noise radiation. According to some sources, trailing edges of airfoils are serrated, jagged, or corrugated. Such shapes reduce trailing-edge noise radiation.

[0029] The acoustic sensor housing is designed in the shape of an airfoil. With this geometry and / or shape, laminar airflow is generated around the housing when the vehicle moves, minimizing turbulent flow. This minimization of turbulent flow essentially prevents aeroacoustic noise generation. The airflow is guided by the edges of the acoustic sensor housing, particularly the profile's contours, in such a way that flow separation is avoided or at least significantly minimized. This design, which reduces flow noise emissions, allows the acoustic sensors to better perceive their surroundings. The surface areas of the airflow and outflow cross-sections of the profile are designed to reduce, rather than accelerate, the flow velocity.Flow deflections and obstructions, and thus flow resistance, are kept to a minimum. The acoustic sensor housing according to the invention, with reduced flow noise emission, enables the advantageous installation of external microphones in the vicinity of vehicles, particularly tractors, for example, trucks. Thanks to the acoustic sensor housing with reduced flow noise emission, the acoustic sensors can be oriented against the direction of travel in areas exposed to airflow, particularly in vehicles whose design or intended use does not permit the acoustic sensors to be mounted in a flow-shielded area.

[0030] Another aspect is that the acoustic sensor housing has a flat profile underside. Such an acoustic sensor housing can be advantageously designed mechanically and easily mounted on a vehicle, for example, planarly on the vehicle's outer skin.

[0031] According to another aspect, the invention provides a vehicle, for example, a passenger car, a commercial vehicle such as a truck, or a shuttle. The vehicle comprises one or more acoustic sensor housings without a profiled edge, as described above. A vehicle contour, for example, a bumper, forms the side of the acoustic sensor housing that encompasses the housing section of the acoustic sensor housing. That is, the acoustic sensor is installed behind an existing vehicle contour during use. The vehicle contour, i.e., the housing section of the acoustic sensor housing, is adapted according to the requirements of the acoustic sensor, as described above.

[0032] For example, a 4 mm thick vehicle sheet is tapered to 1.5 mm at the point opposite where the acoustic sensor is located.

[0033] Another aspect involves placing the acoustic sensor behind an existing vehicle contour without altering the vehicle's shape. The requirements for the acoustic sensor can be met, for example, by using materials with low sound attenuation and / or relatively thin profiles.

[0034] According to one aspect, the connection between the remaining acoustic sensor housing and the vehicle component is glued, screwed, or clipped. According to another aspect, a sealing component may be provided to create a seal between the remaining acoustic sensor housing and the vehicle component. According to yet another aspect, the acoustic seal of the circuit board may also be used as a sealing component between the remaining acoustic sensor housing and the vehicle component.

[0035] According to another aspect, the vehicle includes an acoustic sensor housing with a profiled edge as described above. The acoustic sensor housing is positioned on the vehicle such that a leading edge of the profiled acoustic sensor housing faces forward in the direction of travel.

[0036] The invention therefore proposes three variants for the integration of the acoustic sensor into a vehicle: placing the acoustic sensor housing onto an existing vehicle contour, installing it behind an existing vehicle contour with a change in the shape of the vehicle contour, and installing it behind an existing vehicle contour without changing the shape of the vehicle contour.

[0037] In another embodiment, the vehicle is a tractor unit. The acoustic sensor housing is mounted on the tractor unit. The tractor unit can be, for example, a truck with or without a trailer, a semi-trailer truck with or without a semi-trailer, a passenger car with or without a caravan, a tractor with or without a trailer, or a bicycle with or without a bicycle trailer.

[0038] From another perspective, the driving system is a system for automated driving functions. At least one acoustic sensor detects sound from the vehicle's surroundings. The driving system processes signals from the acoustic sensor for trajectory planning. In addition to acoustic sensors, the driving system can include environmental perception sensors such as cameras, radar, lidar, one or more electronic control units (ECUs), and one or more actuators for longitudinal and / or lateral control of the vehicle. The ECU can incorporate a high-performance computing platform for processing sensor signals, perceiving the environment, and controlling the actuators. Automated driving functions include assisted driving and autonomous driving functions.Thanks to its design that reduces airflow noise emissions, the vehicle can, for example, detect approaching emergency vehicles with activated sirens earlier and react accordingly automatically, for example by forming an emergency lane or reducing driving speed to ensure a safe overtaking of the emergency vehicle or a lane change.

[0039] The invention is explained by way of example in the following figures. They show: Fig. 1 a cross-sectional view of an acoustic sensor housing disclosed herein for mounting on an existing vehicle contour, Fig. 2 another cross-sectional view of an acoustic sensor housing disclosed herein for mounting on an existing vehicle contour, Fig. 3 a cross-sectional view of an acoustic sensor housing disclosed herein for installation behind an existing vehicle contour, Fig. 4 a further cross-sectional view of an acoustic sensor housing disclosed herein for installation behind an existing vehicle contour and Fig. 5 Another cross-sectional view of an acoustic sensor housing disclosed herein for installation behind an existing vehicle contour

[0040] In the figures, identical reference numbers denote identical or functionally similar parts. For clarity, only the reference parts relevant to the respective understanding are marked in each figure.

[0041] Fig. Figure 1 shows an acoustic sensor housing 10 in the form of a profile 11. The profile 11 can be mounted onto an existing vehicle contour with a planar underside 19, for example, by screwing it on. The profile 11 has a curved leading edge 16 and a tapered trailing edge 13. The acoustic sensor 15, for example, a MEMS microphone, can be located in the area of ​​the trailing edge 13. Opposite the acoustic sensor 15, the upper surface 18 of the profile has a tapered housing section 10a, which serves as a diaphragm for the acoustic sensor 15. Another housing section 10b of the acoustic sensor housing 10 can be made of a porous material.

[0042] The acoustic sensor 15 is mounted in an interior 12 of the acoustic sensor housing on a circuit board opening 14a that is open on one side. The circuit board opening 14a directs the sound input to the acoustic sensor 15. The circuit board 14 can include other components 15b besides the acoustic sensor 15, for example, an A2B audio bus chip. The circuit board 14 is decoupled from the acoustic sensor housing 10 by means of a sealing component 12b.

[0043] Fig. Figure 2 shows the embodiment of the Fig. 1 with an additional seal 12a between the housing section 10a and the remaining housing section 10b.

[0044] The Fig. Figures 3 to 5 show the acoustic sensor housing 10 installed behind an existing vehicle contour, wherein the housing section 10a is formed by a vehicle contour part 21, for example a bumper.

[0045] Fig. 3 and Fig. Figures 4 each show an embodiment with a tapered vehicle body section 21. However, the invention also includes the fact that the vehicle body section 21, which is part of the acoustic sensor housing 10, remains unchanged in shape due to special material properties. Fig. Figure 4 shows a contour of the acoustic sensor housing 10, in which the seal 12a is also used as a seal between the acoustic sensor housing 10 and the vehicle contour 21.

[0046] Fig. Figure 5 shows an embodiment in which the seal 12a is replaced by a funnel 12c inserted into the acoustic sensor housing 10. This eliminates the need for a relatively large ring for the seal 12a or 12b for acoustic sealing. The sealing ring 12b is then relatively small. Reference sign 10 acoustic sensor housings 10a Housing section 10b Housing section 11 Profile 12 Interior 12a Seal 12b Sealing component 12c funnel 13 Profile trailing edge 14 circuit board 14a Circuit board opening 15 Acoustic sensor 15b Component 16 Profile leading edge 18 Profile top 19 Profile bottom 21 Vehicle inspection

Claims

[1] Acoustic sensor housing (10) for arrangement on a vehicle, wherein at least one printed circuit board (14) comprising at least one printed circuit board opening (14a) open on one side for sound entry is arranged in an interior (12) of the acoustic sensor housing (10) and an acoustic sensor (15) is mounted on the at least one printed circuit board opening (14a), wherein the acoustic sensor housing (10) is closed and at least one housing section (10a) of the acoustic sensor housing (10) opposite the open side of the at least one printed circuit board opening (14a) is made of a material with low acoustic impedance, characterized by , that an edge of the acoustic sensor housing (10) has the form of a profile (11), wherein the profile is an airfoil profile, the housing section (10a) is arranged in a region of a profile trailing edge (13) and the acoustic sensor housing (10) is placed on a vehicle contour, wherein the housing section (10a) is formed integrally with the adjacent housing parts and has a housing thickness less than that of the two adjacent housing parts. [2] Acoustic sensor housing (10) according to claim 1, wherein the material is selected from the substances of the polymers, preferably the synthetic polymers. [3] Acoustic sensor housing (10) according to one of the preceding claims, wherein the housing section (10a) is tapered, preferably to a material thickness of less than 5 mm, particularly preferably to a material thickness of 1.5 mm. [4] Acoustic sensor housing (10) according to one of the preceding claims, wherein the housing section (10a) is decoupled from the rest of the acoustic sensor housing (10) by a seal (12a). [5] Acoustic sensor housing (10) according to one of the preceding claims, wherein the circuit board (14) is coupled to the acoustic sensor housing (10) with sealing components (12b). [6] Acoustic sensor housing (10) according to one of the preceding claims, wherein further housing sections (10b) of the acoustic sensor housing (10) comprise plastic or metal foams, rubber granules or expanded glass granules. [7] Vehicle comprising one or more acoustic sensor housings (10) according to one of claims 1 to 6, wherein the acoustic sensor housing (10) is arranged on the vehicle such that a profile front edge (16) of the acoustic sensor housing (10) is arranged forward in the direction of travel. [8] Vehicle according to claim 7, wherein the vehicle is a tractor unit and the acoustic sensor housing (10) is arranged on the tractor unit. [9] Vehicle according to one of claims 7 or 8 comprising a driving system for automated driving functions, wherein the at least one acoustic sensor (15) detects sound from an environment of the vehicle and the driving system processes signals from the acoustic sensor (15) for trajectory planning.

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