Radome assembly for a radar sensor of a motor vehicle and radar sensor

Abstract

The present invention relates to an antenna cover assembly for a radar sensor of a motor vehicle, wherein the radar sensor of the motor vehicle comprises a radar frequency circuit board having at least one antenna and a radar frequency circuit next to the antenna, wherein the antenna cover assembly comprises: an antenna cover to cover the antenna side of the radar frequency circuit board; and an absorber for radar waves to shield the radar frequency circuit, wherein the absorber is arranged in front of the inner side of the antenna cover, wherein the absorber leaves an area next to the absorber and in front of the inner side of the antenna cover for the main antenna beam of the at least one antenna, wherein the absorber is fixed to the antenna cover, and wherein the antenna cover assembly has at least one elastic plastic element, and the absorber is movably supported on the inner side of the antenna cover via the at least one elastic plastic element.

Description

Technical Field

[0001] The present invention relates to a radome assembly for a radar sensor for a motor vehicle, the radar sensor comprising a radar frequency circuit board having at least one antenna and a radar frequency circuit next to the antenna, wherein the radome assembly comprises: a radome for covering the antenna side of the radar frequency circuit board and an absorber for radar waves so as to shield the radar frequency circuit. The present invention also relates to a radar sensor for a motor vehicle having such a radome assembly. Background Art

[0002] In order to relieve the driver of a motor vehicle, a driver assistance system is known, which includes, for example, comfort functions, such as driving speed regulation (adaptive cruise control, ACC) and safety functions, such as emergency brake assistance. The driver assistance system uses, in particular, measurement data from radar sensors. The advantage of radar sensors is, in particular, that in the case of radar sensors, physical variables, such as the distance and speed of radar targets, are directly measured. In contrast, in the case of video sensors, for example, video images are presented.

[0003] Radar sensors for motor vehicles send high-frequency radar radiation via an antenna structure and receive the radar radiation reflected at objects. These objects can be stationary or movable and can include, for example, vehicles, pedestrians, cyclists or stationary obstacles. The distance and direction angle of the object can be calculated with the help of the received radar signal. In addition, the relative radial velocity of the object relative to the radar sensor can be calculated. Typical radar sensors for motor vehicles operate in the frequency range of 76 to 77 GHz. Summary of the invention

[0004] In radar sensors, it is desirable that high-frequency radar signals are transmitted only to certain, exposed locations in the radar sensor. It is also desirable to reduce or, as far as possible, eliminate interfering signals in the received radar signals. An absorber is installed in the radar sensor, which may be a component that absorbs and shields radar waves, so as to absorb interfering radar waves when transmitting and / or receiving radar signals.

[0005] By plugging or welding the absorber to the radome, a radome assembly with an integrated absorber can be produced. The radome assembly with an integrated absorber has the advantage of particularly simple assembly of the radome and the absorber on the radar sensor, since only the radome assembly with the integrated absorber needs to be assembled for this purpose.

[0006] In order to achieve defined performance characteristics of the radar sensor, it is desirable to arrange the absorber at a defined distance from the antenna side of the radar frequency circuit board of the radar sensor.

[0007] It is particularly desirable to be able to achieve in a radome assembly with an integrated absorber that the absorber is at a defined distance from the antenna side of a radar frequency circuit board of a radar sensor. It is particularly desirable to combine the advantage of particularly simple assembly with the possibility of still ensuring a defined distance between the absorber and the antenna side of the radar frequency circuit board.

[0008] According to the invention, one or more of the above-mentioned objects are achieved with the features described according to the invention. Advantageous embodiments and refinements of the invention are described in a preferred embodiment.

[0009] The absorber is fixed to the radome and supported movably on the inner side of the radome via at least one elastic plastic element, so that when the radome assembly is mounted on the radar sensor, the absorber rests on the antenna side of the radar frequency circuit board and is pressed onto the antenna side of the radar frequency circuit board by the elastic plastic element. Therefore, the distance between the absorber and the radar frequency circuit board can be determined by the absorber, in particular, the absorber rests on the radar frequency circuit board in a defined manner. The elastic plastic element can in particular compensate for the distance tolerance between the absorber and the radome. Therefore, possible tolerance fluctuations in the shape of the radome or in the assembly position of the radome assembly on the radar frequency circuit board or on the housing of the radar sensor can be decoupled from the absorber by at least one elastic plastic element, so that these possible tolerance fluctuations have no direct effect on the distance between the absorber and the antenna side of the circuit board. Therefore, a simple assembly of the absorber on the radar sensor can be achieved, in which a defined distance of the absorber relative to the antenna side of the radar frequency circuit board can still be ensured.

[0010] Thus, the distance between the absorber and the antenna side of the radar board can be precisely determined, while at the same time certain manufacturing tolerances can be tolerated for the radome and / or the position of the radome relative to the radar frequency circuit board that occurs during assembly of the radome assembly, without causing fluctuations in the distance between the absorber and the circuit board that could decisively influence the sensor performance, for example, with regard to the effective range of the sensor. Nevertheless, a production concept for assembling a radar sensor can be realized in which the absorber is fastened to the radome assembly. Thus, in particular, an assembly process can be used in which the radome assembly with the integrated absorber is assembled to the radar sensor in one step.

[0011] In contrast, the direct fastening of the absorber to the radar frequency printed circuit board and the subsequent separate assembly of the radome involve additional, complex production steps in the final production of the radar sensor.

[0012] The radome assembly may also be referred to as a radome assembly or a radome structure. The radome assembly is a radome assembly with an integrated absorber.

[0013] A radar frequency printed circuit board (PCB) includes at least one antenna. Therefore, it is an antenna printed circuit board, also called an "antenna on a PCB". A radar frequency printed circuit board can also be called an HF (high frequency) board or an antenna carrier board.

[0014] The radome is configured to cover the antenna side of the radar frequency circuit board when the radome assembly is mounted on the radar sensor. The radome is preferably configured to cover the antenna side of the radar frequency circuit board in its entirety. That is, the entire antenna side of the radar frequency circuit board is covered.

[0015] Preferably, the radome is particularly configured to shield the radar frequency circuit in a direction perpendicular to the antenna side of the radar frequency circuit board. The absorber can, for example, be configured to shield the radar frequency circuit in a direction parallel to the main direction of the main antenna beam of the at least one antenna.

[0016] The region left free by the absorbent body is preferably a region adjacent to the side surfaces of the absorbent body.

[0017] The freed-up area can be, in particular, an area for emitting signals from at least one antenna of the radar frequency circuit board or for emitting signals into at least one antenna of the radar frequency circuit board.

[0018] The radome may include, on its inner side, for example, a first region in which an absorber is arranged and a second region next to the first region, wherein the absorber leaves the second region free in order to allow radar waves transmitted and received by the radar sensor to pass through the radome.

[0019] The absorber is supported movably on the inner side of the radome by means of the at least one elastic plastic element or is damped movably against the inner side of the radome.

[0020] The at least one elastic plastic element is provided, for example, to provide a pressing force for pressing the absorber onto the antenna side of the radar frequency circuit board in an arrangement where the absorber of the radome assembly lies against the antenna side of the radar frequency circuit board when the radome assembly is mounted on the radar sensor. In this case, the at least one elastic plastic element can accommodate positional tolerances of the radome relative to the radar frequency circuit board. The at least one elastic plastic element is elastically deformable and in particular elastically compressible. The absorber is supported on the radome, for example, by means of the at least one elastic plastic element, in a manner that resists the compression of the absorber and is resiliently resilient.

[0021] The absorber preferably has a raised stop for contacting the radar frequency circuit board. The stop can also be referred to as a support area or a stop surface. The raised stop enables the absorber to be oriented on the radar frequency circuit board. The raised stop preferably ends in a plane. That is to say, there is a plane in which a plurality of raised stops of the absorber end. This enables the absorber to be supported on the radar frequency circuit board at more than just one point.

[0022] The raised stops can be provided in particular for defining the distance between the absorber and the radar frequency circuit board. The stops can be provided in particular for determining the distance of the region of the absorber between the raised stops relative to the radar frequency circuit board when in contact with the radar frequency circuit board. It can thus be achieved, for example, that the middle region of the absorber does not lie directly against the radar frequency circuit board, but rather maintains a defined distance from the radar frequency circuit board.

[0023] In a preferred embodiment, the absorber is formed as a cage that is open on one side. In this case, the open side of the cage faces away from the radome, that is, when the radome assembly is mounted, it faces the radar frequency circuit board. The absorber can, for example, have an empty interior space to receive circuit elements of a radar frequency circuit. When the radome assembly is mounted on the radar sensor, circuit elements of the radar frequency circuit that are mounted on the antenna side of the radar frequency circuit board can, for example, be received in the empty interior space of the absorber that is open on one side.

[0024] Preferably, the at least one elastic plastic element is arranged in the intermediate space between the radome and the absorber. Preferably, the at least one elastic plastic element can free up an area next to the at least one elastic plastic element in front of the inner side of the radome for a main antenna beam of the at least one antenna.

[0025] The at least one elastic plastic element may in particular be at least one elastic spacer. The elastic spacer may in particular be provided for adjusting or compensating a distance between the absorber and the radome when the radome assembly is mounted on the radar sensor.

[0026] The at least one elastic plastic element is preferably at least one elastic support or holding element, such as a cushion, or a component of a support or holding element. The elastic plastic element can in particular be an elastic spacer.

[0027] In one embodiment, the at least one elastic plastic element comprises at least one spring, in particular a compression spring, particularly preferably a helical spring or a bow spring. The spring may be an elastic support.

[0028] In one embodiment, the at least one elastic plastic element comprises at least one pliable pad, in particular an elastic pad. The pliable pad may be an elastic support.

[0029] Preferably, the radome is made of plastic, the absorber is made of plastic, and the plastic material of the at least one elastic element has a dielectric constant that is between the dielectric constant of the plastic material of the absorber and the dielectric constant of the plastic material of the radome. It can thereby be achieved that the dielectric constant of the radome assembly including the absorber increases continuously or decreases continuously from the inside to the outside or remains constant. Thus, unfavorable abrupt changes in the dielectric constant, which would be associated with an alternating change in the dielectric constant, can be avoided.

[0030] The plastic material of the at least one elastic element may be an elastomeric material. The plastic material of the radome and / or the plastic material of the absorber is preferably a non-yielding (inelastic) plastic material.

[0031] According to one embodiment of the invention, the absorber has at least two pins or at least two pin receptacles for cooperating with corresponding counterparts of the radar frequency circuit board to orient the absorber in a direction parallel to the radar frequency circuit board. The absorber preferably has at least two pins, which extend beyond the raised stop to abut against the radar frequency circuit board. Particularly preferably, the stop is formed on the pins. This allows a particularly compact design of the absorber.

[0032] The pin or the pin receptacle can be used to achieve an optimal positioning of the absorber relative to the at least one antenna element or relative to the radar frequency circuit. In particular, the position of the absorber can be determined two-dimensionally or three-dimensionally. In this case, the at least one elastic plastic element can, for example, allow a displacement between the absorber and the radome in a direction parallel to the radar frequency circuit board.

[0033] Furthermore, the subject matter of the invention is a radar sensor for a motor vehicle, comprising: a housing with a housing opening on the front side; a radar frequency circuit board with at least one antenna and a radar frequency circuit next to the antenna; and a radome assembly of the described type, which is arranged at the housing opening on the front side of the housing, wherein an absorber is arranged above the radar frequency circuit and wherein an elastic plastic element presses the absorber onto the antenna side of the radar frequency circuit board. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Hereinafter, embodiments are explained in detail with reference to the accompanying drawings.

[0035] The accompanying drawings show:

[0036] Figure 1 A schematic diagram of the structure of the radome assembly in an assembled state;

[0037] Figure 2 A schematic diagram of a radar sensor having a radome assembly;

[0038] Figure 3 An embodiment of a radome assembly in an assembled condition;

[0039] Figure 4 Additional embodiments of the radome assembly in an assembled state; and

[0040] Figure 5 Another embodiment of a radome assembly in an assembled state. DETAILED DESCRIPTION

[0041] exist Figure 1 , which comprises a radome 12, an absorber 14 and a symbolically shown elastic plastic element 16, which is arranged in the intermediate space between the radome 12 and the absorber 14. The absorber 14 is connected to the radome 12 via the elastic plastic element 16 and fixed to the radome 12. The elastic plastic element 16 is an elastic support for the absorber 14 on the radome 12.

[0042] The absorber 14 is, for example, a plastic part manufactured by an injection molding method. The radome 12 is, for example, a plastic part manufactured by an injection molding method.

[0043] In the schematically shown assembly, the absorber 14 rests on the antenna side 20 of a radar frequency circuit board 22. The circuit board 22 is a printed circuit board antenna system. An antenna structure, which can be an antenna array, is formed on the antenna side 20 of the circuit board 22 and includes an antenna 24.

[0044] exist Figure 1 A main antenna beam 26 of an antenna 24 of an antenna arrangement is schematically shown in FIG. In the example shown, the antenna arrangement with the antenna 24 is arranged on a plurality of areas of the antenna side 20 .

[0045] Furthermore, the circuit board 22 includes a radar frequency circuit 28 , which may include, for example, a MMIC 30 (Monolithic Microwave Integrated Circuit).

[0046] The printed circuit board 22 is supported on the sensor housing, for example on a printed circuit board carrier 32 of the sensor housing.

[0047] As schematically shown, at least one elastic plastic element 16 can generate a restoring force against approaching the radome 12. Thus, tolerance compensation between the radome 12 and the antenna side 20 of the circuit board 22 can be achieved. Thus, even if the position of the radome 12 may be slightly different due to manufacturing tolerances, the absorber 14 can maintain the same distance from the antenna side 20 of the circuit board 22. However, the absorber 14 can be assembled together with the radome 12 as an integrated radome assembly 10, wherein the absorber 14 is placed against the antenna side 20 of the circuit board 22.

[0048] When compressed in a direction perpendicular to the printed circuit board 22 , the at least one elastic plastic element 16 has, for example, an elasticity that corresponds to a certain spring constant.

[0049] As in Figure 1 As schematically shown in FIG. 1 , the absorber 14 is constructed as a cage with one side open (towards the circuit board 22). The absorber 14 also includes a raised stop 34 having a stop surface 36 for abutting against the antenna side 20 of the circuit board 22. The absorber 14 also includes a central absorber section 38 which has a defined distance D relative to the surface of the circuit board 22 on the antenna side 20.

[0050] The stops 34 can be designed, for example, as sections of a wall or a surrounding wall of the absorber 14, or they can protrude in the direction of the printed circuit board 22 at each location separated from the absorber 14. The stops 34 end in a common plane, which corresponds to the surface of the antenna side 20 of the printed circuit board 22. In the case of a surrounding wall, the stops 34 surround the recess on the open side of the absorber 14. The distance D corresponds to the depth of the recess.

[0051] The elastic plastic element 16 is provided to press the absorber 14 with a constant force against the antenna side 20 of the circuit board 22 in the assembled state. A reliable shielding of the MMIC 30 is thus achieved.

[0052] As in Figure 1 It is schematically shown in FIG. 1 that the absorber 14 leaves a region 39 next to the absorber 14 in front of the inner side 12A of the radome 12 free for the main antenna beam 26 of the antenna of the antenna arrangement 24 .

[0053] Figure 2The schematic diagram shows the assembly of a radome assembly 10 on a radar sensor. The radar sensor shown comprises a radome assembly 10 having a radome 12, an absorber 14 and at least one elastic plastic element 16, an intermediate carrier in the form of a housing frame 40, a housing bottom 42 and a power supply circuit board 44 (Power PCB), on which a circuit board carrier 32 is formed, which is connected to a radar frequency circuit board 22 via an electrical connection 46 on the rear side of the radar frequency circuit board.

[0054] exist Figure 3 In the exemplary embodiment shown in , the at least one elastic plastic element 16 is implemented in the form of one or more compression springs 48 made of plastic. The exemplary embodiment corresponds to Figure 1 The dielectric constant of the material of the compression spring 48 lies between the dielectric constant of the material of the absorber 14 and the dielectric constant of the material of the radome 12 .

[0055] The radome assembly 10 having the absorber 14 pre-assembled on the radome 12 via the compression spring 48 can be mounted on the radar sensor as a pre-assembled component during assembly of the radar sensor.

[0056] exist Figure 4 In the exemplary embodiment shown in , the at least one elastic plastic element is designed as an elastomer pad 50. The elastomer pad 50 is supported on the entire surface of the radome 12 and the absorber 14, for example, on two opposite sides. The material of the elastomer pad 50 has a dielectric constant between the dielectric constant of the material of the absorber 14 and the dielectric constant of the material of the radome 12. The radome assembly 10 otherwise corresponds to Figure 1 .

[0057] exist Figure 5 In the embodiment shown in , the absorber additionally comprises pins 52 protruding in the direction of the circuit board 22, which are engaged in a form-fitting manner in openings 54 of the circuit board 22, for example in the form of through holes, and orient the absorber 14 at the openings 54 in a direction parallel to the circuit board 22. At least one elastic plastic element 16, for example in the form of an elastomer pad 50, allows a compensating movement of the absorber 14 in the corresponding direction along the inner side 12A of the antenna cover 12. The stop 34 is formed on the pin 52, for example on the periphery of the pin 52. The embodiment described can correspond to the embodiment described in other respects. Figure 3 or Figure 4 .

[0058] The absorption body 14 can be aligned or centered in a defined position relative to the circuit board 22 by the interaction of the pins 52 and the openings 54 .

[0059] Replacement Figure 5By way of example, the arrangement may be reversed: protruding pins are formed on the circuit board 22 on the antenna side, which engage in corresponding openings on the side of the absorber 14 facing the circuit board 22 in order to orient the absorber 14 .

Claims

1. A radome assembly for a radar sensor for a motor vehicle, the radar sensor comprising a radar frequency circuit board (22) having at least one antenna (24) and a radar frequency circuit (28) adjacent to the antenna (24), wherein: The radome assembly comprises: a radome for covering the antenna side (20) of the radar frequency circuit board (22); and an absorber (14) for radar waves to shield the radar frequency circuit (28), The absorber (14) is arranged in front of the inner side (12A) of the antenna cover (12). The absorber (14) leaves a region (39) adjacent to the absorber (14) and in front of the inner side of the radome (12) free for a main antenna beam (26) of the at least one antenna (24). The absorber (14) is fixed on the antenna cover (12), and The antenna cover assembly (10) has at least one elastic plastic element (16), which is arranged in the intermediate space between the absorber (14) and the antenna cover (12) and the absorber (14) is movably supported on the inner side (12A) of the antenna cover (12) via the at least one elastic plastic element.

2. The radome assembly according to claim 1, wherein: The absorber (14) has a protruding stop portion (34) for abutting against the radar frequency circuit board (22).

3. The radome assembly according to claim 1 or 2, wherein: The absorber (14) forms a half-open cage, wherein the open side faces away from the radome (12).

4. The radome assembly according to claim 1 or 2, wherein: The at least one elastic plastic element (16) is at least one elastic support.

5. The radome assembly according to claim 1 or 2, wherein: The at least one elastic plastic element (16) comprises at least one spring (48).

6. The radome assembly according to claim 1 or 2, wherein: The at least one elastic plastic element (16) comprises at least one elastic pad (50).

7. The radome assembly according to claim 1 or 2, in, The radome (12) is made of plastic. Wherein, the absorbent (14) is made of plastic. And wherein the plastic material of the at least one elastic plastic element (16) has a dielectric constant that is between the dielectric constant of the plastic material of the absorber (14) and the dielectric constant of the plastic material of the radome (12).

8. The radome assembly according to claim 1 or 2, wherein: The absorber (14) has at least two pins (52) or at least two pin receptacles for cooperating with corresponding counterparts (54) of the radar frequency circuit board (22) in order to orient the absorber (14) in a direction parallel to the radar frequency circuit board (22).

9. A radar sensor for a motor vehicle, comprising: A housing (40, 42) having a front housing opening; a radar frequency circuit board (22) having at least one antenna (24) and radar frequency circuitry (28) adjacent to the antenna (24); and A radome assembly (10) is arranged at the front shell opening of the shell (40, 42), in, The radome assembly (10) comprises: a radome (12) covering the antenna side (20) of the radar frequency circuit board (22); and an absorber (14) for radar waves, the absorber being arranged above the radar frequency circuit (28), The absorber (14) is arranged in front of the inner side (12A) of the antenna cover (12). The absorber (14) leaves a region (39) next to the absorber (14) and above the at least one antenna (24) free for a main sky beam (26) of the at least one antenna (24), wherein the absorber (14) is fixed on the antenna cover (12), and The radome assembly (10) comprises at least one elastic plastic element (16), the at least one elastic plastic element being arranged in the intermediate space between the absorber (14) and the radome (12), and the absorber (14) being supported on the inner side (12A) of the radome (12) via the at least one elastic plastic element, Therein, the elastic plastic element (16) presses the absorber (14) onto the antenna side (20) of the radar frequency circuit board (22).

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