Radar sensor for a motor vehicle with curved housing part, driver assistance system and motor vehicle

Abstract

Radar sensor (4) for a motor vehicle (1), with at least one antenna element (8) for emitting electromagnetic radiation and / or for receiving the electromagnetic radiation reflected by an object in a surrounding area (7) of the motor vehicle (1), and with a housing (10) which comprises a housing part (11) through which the at least one antenna element (8) emits and / or receives the electromagnetic radiation, characterized in that the radar sensor (4) has at least one contact element (20) for electrically contacting the radar sensor, wherein the at least one contact element (20) is at least partially cast into a material of the housing (10), wherein the housing (10) is substantially hollow-cylindrical in a first region (18) and a cross-sectional area of ​​the housing (10) tapers in a second region (19) in which the at least one contact element (20) is cast into the material of the housing (10), and the housing part (11) is concave on an inner side (21) facing the at least one antenna element (8).

Description

[0001] The present invention relates to a radar sensor for a motor vehicle, comprising at least one antenna element for emitting electromagnetic radiation and / or for receiving the electromagnetic radiation reflected by an object in a surrounding area of ​​the motor vehicle, and comprising a housing that includes a housing part through which the at least one antenna element emits and / or receives the electromagnetic radiation. The invention also relates to a driver assistance system having at least one such radar sensor. Finally, the present application relates to a motor vehicle having such a driver assistance system.

[0002] The focus here is on radar sensors for motor vehicles. These radar sensors are generally used to detect an object in the area surrounding the motor vehicle. The radar sensors can be part of various driver assistance systems that support the driver in driving the motor vehicle. On the one hand, the radar sensors measure the distance between the object and the motor vehicle. On the other hand, the radar sensors also measure the relative speed to the object. Furthermore, the radar sensors can also determine a so-called target angle, i.e., an angle between an imaginary connecting line to the object and a reference line, such as the vehicle's longitudinal axis.

[0003] Radar sensors are usually placed behind the bumper of a motor vehicle, for example, in the respective corner areas of the bumper. To detect the object, the radar sensor emits a transmission signal in the form of an electromagnetic wave. This transmission signal is then reflected by the object to be detected and received again by the radar sensor as an echo. The radar sensor has at least one antenna element to emit the electromagnetic radiation and / or to receive the electromagnetic radiation reflected by the object. Furthermore, such radar sensors have a corresponding housing for protection against environmental influences. The housing has a housing part through which the electromagnetic radiation is emitted and through which the electromagnetic radiation reflected by the object is received by the antenna element. Such a housing part can also be referred to as a radome.Such a radome can also be designed in such a way that it serves to specifically influence the radiation characteristics of the radar sensor.

[0004] The radar sensors known from the prior art usually have a flat radome or a plate-shaped radome. For example, Fig. 2 shows a radar sensor 4 according to the prior art in a sectional side view. The radar sensor 4 has a carrier element 9 or a substrate, on which an antenna element 8 is arranged in the present case. In addition, the radar sensor 4 has a housing 10 with a housing part 11 or the radome, which is flat. If the antenna element 8 is to have a large field of view, the radiation characteristic of the antenna element 8 is negatively influenced at large angles when the flat housing part 11 or the radome is used. The beam path through the housing part 11 becomes increasingly longer with increasing radiation angle α. This is illustrated here using the beam paths S1, S2, and S3 of the electromagnetic radiation.Since the housing part 11 has a higher dielectric constant than the air surrounding the housing part 11, the beam path S1, S2, S3 starting from the antenna element 9 is diffracted at the lower boundary between air and the housing part 11 towards the vertical 12, so that the beam path S1, S2, S3 has the angle β to the vertical 12.

[0005] Depending on the radiation angle α, radiation paths of varying lengths through the housing part 11 result. This results in a phase shift of the individual beams relative to one another, which changes the original radiation characteristics of the antenna element 9, particularly at large radiation angles α. Typically, this results in additional unevenness in the radiation characteristics of the radar sensor 4 with a radome compared to a configuration without a radome, which can also be referred to as ripple. The various multiple reflections of the electromagnetic radiation, represented here by the dashed lines 13, which arise at the boundaries between the housing part 11 and the air, additionally influence the radiation characteristics.

[0006] Fig. Figure 3 shows the radar sensor 4 according to the prior art in a further embodiment. Here, the radar sensor 4 has a plurality of antenna elements 8. In addition, the radar sensor 4 has a shielding housing 14 for the electronic components. As can be seen from Fig. As can be seen in Figure 3, it is not always possible to position the antenna elements 8 centrally within the housing 10. The inner edge of the housing 10 is often only a few millimeters larger than the outer edge of the support element 9. This results in additional interference from the housing edges on the radiation characteristics of the overall arrangement at large radiation angles α. This is illustrated here by beam paths S4 and S5.

[0007] In this context, DE 10 2005 035 814 A1 describes a radome for a radar system of a motor vehicle. The radome has a flat interface on which a dielectric lens with a plurality of essentially cylindrical lens elements is arranged, in particular glued. The lenses serve, in particular, to focus incident radiation and feed it to a receiver of the radar system.

[0008] DE 196 22 755 A1 discloses a lens for focusing millimeter waves for distance sensors for a vehicle. The lens covers a housing for the distance sensor.

[0009] DE 44 12 770 A1 discloses a microwave lens arrangement for a motor vehicle distance warning radar. Three exciters are arranged in a focal plane of a stepped lens.

[0010] From EP 0884799 B1 a semiconductor module is known which comprises an antenna element.

[0011] From DE 10 2007 036 262 A1 a radar sensor for motor vehicles with a transmitting and receiving device for microwaves is known, in which independent beam forming devices for the azimuth and the elevation are provided.

[0012] The object of the present invention is to provide a solution as to how a radar sensor for a motor vehicle of the type mentioned above can be operated more reliably.

[0013] This object is achieved according to the invention by a radar sensor, a driver assistance system, and a motor vehicle having the features according to the respective independent patent claims. Advantageous embodiments of the invention are the subject of the dependent patent claims, the description, and the figures.

[0014] A radar sensor according to the invention for a motor vehicle comprises at least one antenna element for emitting electromagnetic radiation and / or for receiving the electromagnetic radiation reflected by an object in a surrounding area of ​​the motor vehicle. Furthermore, the radar sensor has a housing comprising a housing part through which the at least one antenna element emits and / or receives the electromagnetic radiation. Furthermore, the housing part is concave on an inner side facing the at least one antenna element.

[0015] The radar sensor is used to detect an object in the surrounding area of ​​the motor vehicle. The radar sensor can, for example, be part of a driver assistance system that supports the driver in driving the motor vehicle. The radar sensor has at least one antenna element, by means of which a transmission signal or a radar signal can be emitted in the form of electromagnetic radiation. In particular, a radar signal or electromagnetic radiation in a frequency range between 76 and 81 GHz can be emitted using the antenna element. This emitted electromagnetic radiation strikes the object to be detected in the surrounding area of ​​the motor vehicle and is reflected by it. The reflected electromagnetic radiation reaches the antenna element of the radar sensor and is received by it.The distance to the object can be determined based on the propagation time between the emission of the electromagnetic radiation and the reception of the electromagnetic radiation reflected by the object. The at least one antenna element is arranged within a housing of the radar sensor. The housing has a housing part, which can also be referred to as a radome. The at least one antenna element emits the electromagnetic radiation through the housing part. In addition, the electromagnetic radiation reflected by the object is received through the housing part.

[0016] In the present case, the housing part is concave on an inner side facing the at least one antenna element. In other words, the inner side of the housing, which faces the antenna element, is curved. The housing part can therefore have an inward curvature. In comparison to a flat housing part or straight housing part, which is known from the prior art, it can be achieved that the beam path of the electromagnetic radiation is less influenced both during transmission and reception of the electromagnetic radiation. In particular, the shape of the housing part can ensure that the emission of the electromagnetic radiation at a large angle through the housing part or the radome is hardly influenced at all. Due to the curvature of the housing part, the electromagnetic radiation passes predominantly straight through the radome.The diffraction effects are therefore significantly lower than with a flat or plate-shaped radome according to the state of the art. This allows for more reliable detection of objects in the area surrounding the vehicle.

[0017] According to the invention, the radar sensor has at least one contact element for electrically contacting the radar sensor, wherein the at least one contact element is at least partially cast into a material of the housing. The antenna element and / or the transmitting and / or receiving device can be electrically contacted with the at least one contact element. For example, an electrical connection and / or a data connection to the motor vehicle can be provided. The radar sensor and / or the transmitting and / or receiving device can be supplied with electrical energy via the at least one contact element. Furthermore, data signals can be exchanged between the radar sensor and the motor vehicle, in particular a control device or a control unit of the motor vehicle. The at least one contact element can be led outwards in a lateral region of the housing.In this area, the at least one contact element is preferably cast into the housing or the housing material. It can also be provided that at least a portion of the support element is cast into the housing. Thus, the contact element and / or the support element can be mechanically connected to the housing or the housing part.

[0018] According to the invention, the housing is essentially hollow-cylindrical in a first region, and a cross-sectional area of ​​the housing tapers in a second region in which the at least one contact element is cast into the material of the housing. In this embodiment, the entire housing of the radar sensor is hollow-cylindrical in the first region. The cross-sectional area of ​​the housing tapers in at least one edge region or a second region of the housing. In this second region, the housing is mechanically connected to the at least one contact element and / or the carrier element. In this region, the at least one contact element and / or the carrier element is cast into the material of the housing. This enables simple and cost-effective production of the radar sensor.

[0019] Preferably, the inner side of the housing part and / or an outer side of the housing part opposite the inner side has the shape of a portion of a spherical surface, an ellipsoidal surface, or a cylindrical surface. In other words, a wall of the housing part can have the shape of a hollow sphere, a hollow ellipsoid, or a hollow cylinder. The housing part can also have the shape of a lens. The shape of the housing part or of the radome can be adapted to the arrangement of the at least one antenna element relative to the housing part. This reliably prevents the emitted electromagnetic radiation from being influenced by the housing part, particularly when emitted at a large angle.

[0020] Furthermore, it is advantageous if the radar sensor has a carrier element which is arranged in an interior space of the housing and which is formed at least partially from a ceramic. The radar sensor can have a carrier element or a substrate on which the at least one antenna element is applied. The carrier element is formed at least partially or at least regionally from a ceramic. In particular, the carrier element is formed from a low-temperature cofired ceramic (LTCC). With such a carrier element, for example, a compact arrangement can be achieved. Circuits and electronic components can also be provided on the ceramic. For example, the antenna element can have dimensions of 30 mm by 15 mm. This makes it possible to provide a particularly space-saving radar sensor.

[0021] In one embodiment, the radar sensor has a transmitting and / or receiving device which is electrically connected to the at least one antenna element, wherein the at least one antenna element is arranged on a first side of the carrier element and the transmitting and / or receiving device is arranged on a second side of the carrier element opposite the first side. The transmitting and / or receiving device can also be referred to as a transceiver or transceiver module. By arranging the at least one antenna element on a first side and the transmitting and / or receiving device on the opposite second side, a space-saving arrangement can be achieved. The electromagnetic radiation emitted by the antenna element can be provided by the transmitting and / or receiving device.In addition, the transmitting and / or receiving device can receive and evaluate the electromagnetic radiation received by the antenna element. For this purpose, the antenna element is electrically connected to the transmitting and / or receiving device. For example, a corresponding through-hole connection can be provided in the carrier element. This enables a compact design of the transmitting and / or receiving device of the radar sensor, opening up new possibilities for the design of the housing part or the radome.

[0022] Furthermore, it is advantageous if the housing is designed such that the pressure in the interior of the housing is lower than the atmospheric pressure outside the housing. In other words, a negative pressure is created in the interior of the housing. The housing of the radar sensor can, for example, be evacuated. A vacuum can also exist in the interior of the housing. The lower pressure in the interior of the housing can, for example, ensure that the at least one antenna element and the associated electronics can be optimally protected from moisture.

[0023] In one embodiment, the housing part is at least partially formed from a plastic. Such a plastic can be, for example, a thermoplastic, in particular polybutylene terephthalate (PBT). Using such a plastic, the housing or housing part can be easily manufactured and shaped accordingly, for example, using a forming process. Polyamide (PA) can also be used as the plastic. This material is particularly characterized by its high durability.

[0024] In a further embodiment, the housing part is formed at least partially from glass. When the housing part is made of glass, different shapes can be provided. Furthermore, the material is transparent, allowing the radar sensor components inside the housing to be visually inspected. Furthermore, glass is characterized by its high resistance to environmental influences.

[0025] A driver assistance system according to the invention for a motor vehicle comprises at least one radar sensor according to the invention. The driver assistance system can also comprise multiple radar sensors. The driver assistance system can, for example, be an adaptive cruise control system, a lane keeping assistant, a lane change assistant, and / or a blind spot monitoring system.

[0026] A motor vehicle according to the invention comprises a driver assistance system according to the invention. The motor vehicle is designed, in particular, as a passenger car.

[0027] The preferred embodiments presented with reference to the radar sensor according to the invention and their advantages apply accordingly to the driver assistance system according to the invention and to the motor vehicle according to the invention.

[0028] Further features of the invention emerge from the claims, the figures and the description of the figures. The features and combinations of features mentioned above in the description, as well as the features and combinations of features mentioned below in the description of the figures and / or shown alone in the figures can be used not only in the respective combination specified, but also in other combinations or on their own, without departing from the scope of the invention. Embodiments are therefore also to be regarded as encompassed and disclosed by the invention which are not explicitly shown and explained in the figures, but which emerge and can be produced by separate combinations of features from the explained embodiments. Embodiments and combinations of features are also to be regarded as disclosed which therefore do not have all the features of an originally formulated independent claim.

[0029] The invention will now be explained in more detail using preferred embodiments and with reference to the accompanying drawings.

[0030] Showing: Fig. 1 is a schematic representation of a motor vehicle according to an embodiment of the present invention; Fig. 2 a radar sensor according to the prior art, which has a flat housing part; Fig. 3 the radar sensor according to Fig. 2 in a further embodiment; Fig. 4 a radar sensor according to the invention in a sectional side view; and Fig. 5 the radar sensor according to the invention in a perspective view; Fig. 6 the radar sensor according to the invention in a side view; Fig. 7 a detailed view according to Fig. 5; and Fig. 8 an antenna diagram of the radar sensor according to the invention.

[0031] In the figures, identical and functionally identical elements are provided with the same reference symbols.

[0032] Fig. 1 shows a motor vehicle 1 according to an embodiment of the present invention. In the present exemplary embodiment, the motor vehicle 1 is configured as a passenger car. The motor vehicle 1 includes a driver assistance system 2, which can be configured, for example, as an adaptive cruise control system, a blind spot assistant, a lane keeping assistant, and / or a lane change assistant.

[0033] The driver assistance system 2 comprises at least one radar sensor 4, with which an object in a surrounding area 7 of the motor vehicle 1 can be detected. In the present case, the at least one radar sensor 4 can detect an object located in the surrounding area 7 behind the motor vehicle 1. The at least one radar sensor 4 can emit a transmission signal in the form of electromagnetic radiation, which is reflected by the object. The reflected electromagnetic radiation returns to the radar sensor 4 as an echo signal. Based on the propagation time, a distance between the radar sensor 4 and the object can be determined. In principle, the radar sensor can be arranged in a front area 6 and / or a rear area 5 of the motor vehicle 1.

[0034] In the present exemplary embodiment, the motor vehicle 1 or the driver assistance system 2 comprises two radar sensors 4 arranged in a rear region 5 of the motor vehicle 1. The radar sensors 4 can, for example, be arranged concealed behind a bumper of the motor vehicle 1. In addition, the motor vehicle 1 or the driver assistance system 2 comprises a control device 3. The control device 3 can, for example, be formed by a computer, a digital signal processor, or the like. The control device 3 can also be formed by a control unit (ECU - Electronic Control Unit) of the motor vehicle 1.

[0035] Fig. 4 shows an embodiment of a radar sensor 4 according to the invention in a sectional side view. The radar sensor 4 has a carrier element 9 or a substrate. The carrier element 9 can be formed from a ceramic. A plurality of antenna elements 8 are arranged on a first side 15 of the carrier element 9. The antenna elements 8 can transmit a transmission signal in the form of an electromagnetic wave, and the electromagnetic wave reflected by the object can be received again. A transmitting and / or receiving device 17 is arranged on a second side 16 of the carrier element 9, opposite the first side 15. The transmitting and / or receiving device 17 can also be referred to as a transceiver. The transmitting and / or receiving device 17 is in particular electrically connected to the antenna elements 8.

[0036] The radar sensor 4 has a housing 10 in which the carrier element 9, the antenna elements 8, and the transmitting and / or receiving device 17 are arranged. The housing 10 can be made, for example, from a plastic or glass. The pressure in an interior space 22 of the housing can be lower than the atmospheric pressure outside the housing 10. The housing 10 has a housing part 11 or a radome. The electromagnetic radiation can be emitted through the housing part 11, and the electromagnetic radiation reflected by the object can also be received by the housing part 11. In the present case, the housing part 11 is designed such that it is convex on an inner side 21. The housing part 11 can, for example, be substantially spherical, cylindrical, and / or ellipsolid-shaped.The shape ensures that the electromagnetic radiation is not negatively affected, especially at large beam angles. This is illustrated here using beam paths S6, S7, and S8 as examples.

[0037] Fig. 5 shows the radar sensor 4 in a perspective view. It can be seen that the housing 10 is essentially hollow-cylindrical in a first region 18. In a second region 19, a cross-sectional area of ​​the housing 10 tapers. The radar sensor 4 has a plurality of contact elements 20 that extend laterally out of the housing 10. The housing 10 is designed such that the contact elements 20 are cast with the housing 10 in the second region 19. It can also be provided that at least a part of the carrier element 9 is cast with the housing 10 in the second region 19. In the present case, the shape of the housing resembles a light source, in particular a halogen bulb.

[0038] Fig. 6 shows the radar sensor 6 according to Fig. 5 in a side view. Here, the electrical connection between the contact elements 20 and the carrier element 9 can be seen. A voltage supply for the radar sensor 4 can be provided via the contact elements 20. In addition, data can be transmitted to the motor vehicle 1 and data can be received from the motor vehicle 1 via the contact elements 20. Furthermore, Fig. 6 that the cross-sectional area tapers in the second region 19. To achieve this shape, the housing 10 can be deformed accordingly in the second region 19. Fig. 7 shows a detailed view of the second area 19 and the contact elements 20.

[0039] Fig. 8 shows an antenna diagram 23. The antenna diagram 23 represents a radiation characteristic 24 (beam pattern) of the radar sensor 6 together with the housing part 11. Fig.Figure 8 shows a simulated radiation pattern 24. It can be seen that with an asymmetrical antenna position relative to the housing part 11 or the radome, a deviation in the angle of the straight-ahead radiation is to be expected. This must be taken into account when designing the radar sensor or the system comprising antenna elements 9 and the housing part 11 or the radome.

Claims

[1] Radar sensor (4) for a motor vehicle (1), with at least one antenna element (8) for emitting electromagnetic radiation and / or for receiving the electromagnetic radiation reflected by an object in a surrounding area (7) of the motor vehicle (1) and with a housing (10) which comprises a housing part (11) through which the at least one antenna element (8) emits and / or receives the electromagnetic radiation, characterized by , that the radar sensor (4) has at least one contact element (20) for electrically contacting the radar sensor, wherein the at least one contact element (20) is at least partially cast into a material of the housing (10), wherein the housing (10) is substantially hollow-cylindrical in a first region (18) and a cross-sectional area of ​​the housing (10) tapers in a second region (19) in which the at least one contact element (20) is cast into the material of the housing (10), and the housing part (11) is concave on an inner side (21) facing the at least one antenna element (8). [2] Radar sensor (4) according to claim 1, characterized by that the inner side (21) of the housing part (11) and / or an outer side of the housing part (11) opposite the inner side (21) has a shape of a section of a spherical surface, an ellipsoidal surface or a cylindrical surface. [3] Radar sensor (4) according to claim 1 or 2, characterized by that the radar sensor (4) has a carrier element (9) which is arranged in an interior space (22) of the housing (10) and which is at least partially formed from a ceramic. [4] Radar sensor (4) according to claim 3, characterized by that the radar sensor (4) has a transmitting and / or receiving device (17) which is electrically connected to the at least one antenna element (8), wherein the at least one antenna element (8) is arranged on a first side (15) of the carrier element (9) and the transmitting and / or receiving device (17) is arranged on a second side (16) of the carrier element (9) opposite the first side (15). [5] Radar sensor (4) according to one of the preceding claims, characterized by that the housing (10) is designed such that a pressure in an interior space (22) of the housing (10) is lower than an atmospheric pressure outside the housing (10). [6] Radar sensor (4) according to one of the preceding claims, characterized by that the housing part (11) is at least partially formed from a plastic. [7] Radar sensor (4) according to one of claims 1 to 5, characterized bythat the housing part (11) is at least partially formed from a glass. [8] Driver assistance system (2) for a motor vehicle (1) with at least one radar sensor (4) according to one of the preceding claims. [9] Motor vehicle (1) with a driver assistance system (2) according to claim 8.

Images