Radar Sensor

Abstract

The present invention relates to a radar sensor comprising a waveguide antenna (7), a radome (1), a housing (3) to which the radome (1) is fixed, and a circuit board (4) on which the waveguide antenna (7) is positioned. The waveguide antenna (7) and the radome (1) are matingly connected to each other.

Description

[Technical field]

[0001] The present invention relates to a radar sensor comprising a waveguide antenna and a radome, which can be used, for example, in the automotive industry. [Background technology]

[0002] In radar sensors, in recent years, waveguide antennas are often used, which comprise a waveguide structure for transmitting and receiving radar waves. The waveguide antenna is connected to a circuit board and is supplied with radar waves by electrical components located on the circuit board. Conventionally, the waveguide antenna is fixed directly to the circuit board. To protect the radar sensor and the waveguide antenna from external influences, the radar sensor comprises a radome. The radome is arranged in the direction of radiation, i.e. typically on the side of the antenna opposite the circuit board, and is transparent to the radar waves. In many cases, the radome is fixed to the housing of the radar sensor, to which the circuit board is also fixed. Summary of the Invention [Means for solving the problem]

[0003] A radar sensor is proposed which comprises a waveguide antenna and a radome, in which the radome and the waveguide antenna are matingly connected to one another, i.e. the waveguide antenna and the radome are already firmly connected to one another before assembly in the radar sensor. In other words, the waveguide antenna is integrated in the radome. The waveguide antenna and the radome can thus be produced in advance as an assembly and can already be adapted to one another, which simplifies production. As the radome and the waveguide antenna are firmly connected to one another, the distance between the radome and the radiation surface of the waveguide antenna, which is important for the performance of the radar sensor, does not change even in the event of vibrations or deformations.

[0004] Finally, the assembly is assembled into the housing of the radar sensor, where the radome is fixed to the housing, preferably by a laser welding method. The distance dimensions determined in advance for the manufacture of the radar sensor and the radome-waveguide antenna assembly can be used as input parameters for the laser welding method. This allows the distance between the waveguide antenna and the circuit board to be precisely adjusted. During assembly, the waveguide antenna is positioned through the circuit board by a positioning element of the waveguide antenna engaging into a corresponding guiding element of the circuit board. As an example, the positioning element is configured as a pin extending from the waveguide antenna, and the guiding element is an opening in the circuit board. For guidance, the pin engages into the corresponding opening.

[0005] Further fastening of the waveguide antenna to the circuit board may become unnecessary, since the waveguide antenna is already firmly fixed to the radome. The radome-waveguide antenna assembly is held only by the fastening of the radome to the housing. Thus, the number of fastening and / or guiding elements provided on the circuit board can be reduced, which reduces the space required on the circuit board. In particular, two guiding elements on the circuit board are sufficient for fastening the assembly. Lateral misalignments between the launcher and the port of the waveguide antenna on the circuit board can be compensated with short tolerance chains by the positioning and / or guiding elements.

[0006] Fastening via the housing decouples the waveguide antenna and the circuit board from each other: forces acting on the waveguide antenna are not received by the circuit board, which reduces the load on the connection between the circuit board and the housing, especially when the radar sensor is subjected to vibration loads.

[0007] For the mating connection technique, the radome is preferably equipped with a pin that extends through the waveguide antenna, preferably to the other side, and is connected to the waveguide antenna. The pin allows for a simple mating connection.

[0008] As a preferred mating connection technique, a heat crimping process can be used. In heat crimping, a plastic dome is melted by heat and then deformed under pressure. As the plastic dome, preferably the above-mentioned pin of the radome is used to function as the heat crimping pin. The heat crimping pin of the radome extends through the waveguide antenna and then melts and deforms on the opposite side to abut against the waveguide antenna. Preferably, the waveguide antenna has a recess into which the deformed heat crimping pin fits.

[0009] Optionally, the waveguide antenna has at least one protrusion extending from the body in which the waveguide is arranged. The mating connection between the radome and the waveguide antenna is made at this at least one protrusion. Preferably, a pin, in particular a heat crimped pin, can be extended through this at least one protrusion and engage with the protrusion on the opposite side. As a result, the mating connection is realized outside the waveguide antenna body and no space is required in the body for the mating connection. As a result, a smaller overall structure can be realized.

[0010] Furthermore, a method for manufacturing a radar sensor is proposed. First, a waveguide antenna and a radome are provided. The waveguide antenna and the radome are adapted to each other in shape and size, and also to the housing and the circuit board to be connected later. The distance between the waveguide antenna and the circuit board is also defined. In the waveguide antenna, the waveguide is already configured accordingly. The radome is then matingly connected to the waveguide antenna to form a radome-waveguide antenna assembly. As mentioned above, a thermal crimping process is used as a preferred mating joining technique. The above steps are already performed before the assembly of the housing and the circuit board. Thus, the radome-waveguide antenna assembly can be pre-manufactured and provided, for example, by a supplier. Finally, during assembly, the radome-waveguide antenna assembly including the radome is assembled to the housing. For connecting the radome to the housing, preferably the above-mentioned laser welding method is used.

[0011] Overall, the radar sensor can be cost-effectively and manufacturable using standardized processes for mass production. Exemplary embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description. [Brief description of the drawings]

[0012] [Figure 1] 1 is a cross-section through a radar sensor according to a first embodiment of the invention; [Diagram 2] FIG. 4 is a cross-section through a radar sensor according to a second embodiment of the invention. [Figure 3a] FIG. 3a is a top view of a waveguide antenna with thermal crimp pins in a radome in one arrangement. [Figure 3b] FIG. 3b is a top view of the waveguide antenna with the thermal crimp pins of the radome in an alternative arrangement. [Figure 3c] FIG. 3c is a top view of the waveguide antenna with the thermal crimp pins of the radome in an alternative arrangement. [Figure 3d] FIG. 3d is a top view of the waveguide antenna with thermal crimp pins on the radome in another arrangement. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] In Fig. 1 a first embodiment of a radar sensor according to the invention is shown. The radar sensor comprises a waveguide antenna 7, a radome 1, a housing 3 and a circuit board 4. The circuit board 4 comprises a chip 6 with a launcher for generating radar waves. The circuit board 4 is fixed directly to the housing 3. According to the invention, the waveguide antenna 7 is matingly connected to the radome 1. For this purpose, the radome 1 is provided with thermal crimping pins 2, two of which are shown in Fig. 1. During manufacture, the thermal crimping pins 2 are inserted into the openings of the waveguide antenna 7 and extend through them to the opposite side (called here the back side, located opposite the radiation surface). On the back side, the waveguide antenna 7 in this exemplary embodiment has a recess 8 at the position of each thermal crimping pin 2, into which the head of the thermal crimping pin 8 fits. During the heat crimping process, heat and pressure force the head of the heat crimp pin 2 against the backside, deforming it and the waveguide antenna 7 is "pressed in" by the heat crimp pin 2, creating a mating connection. This forms an integrated radome-waveguide antenna assembly. During the heat crimping process, the tool-specific dimensions define the distance D between the radiating surface of the waveguide antenna 7 and the radome 1, which is critical to the performance of the radar sensor. The mating connection keeps the distance D constant throughout the life of the radar sensor and protects it from vibrations or other deformations.

[0014] Furthermore, the waveguide antenna 7 is provided on its backside with a pin-shaped positioning element 5. When assembling the radome 1 and the waveguide antenna 7 to the housing 3 and the circuit board 4, in a pre-joining step the positioning element 5 is pre-centered through the opening in the circuit board 4. The positioning element 5 ensures that the lateral position of the waveguide antenna 7 relative to the launcher at the chip 6 is accurately maintained during pre-joining, laser welding and final installation of the radar sensor. During assembly, the radome 1 is connected to the housing 3 by a laser welding method. Here, the distance A between the waveguide antenna 7 and the circuit board 4, which is important for the correct coupling or decoupling of the radar waves, is adjusted. To adjust the distance A, the distance B between the connection position of the radome 1 and the circuit board 4 and the distance C between the connection position of the radome 1 and the backside of the waveguide antenna 7 are determined. The distance C is determined during the connection of the radome 1 and the waveguide antenna 7 and then transmitted to the manufacturing station of the laser welding method by a data matrix code or another data transmission method. Then, before laser welding, a distance B is calculated from the sum of the distance C and the predefined distance A, and the laser welding method is performed at the calculated distance B.

[0015] In Fig. 2, a second embodiment of a radar sensor according to the invention is shown. The same components are characterized by the same reference numbers, and reference is made to the above description. The second embodiment differs from the first embodiment only in that the waveguide antenna 7 comprises protrusions 9 and the thermal crimping pins 2 extend through these protrusions 9. As a result, the thermal crimping pins 2 are located outside the body of the waveguide antenna 7, which can be made smaller than in the first embodiment. During the thermal crimping process, the head of the thermal crimping pin 2 is pressed against the back side of the protrusions 9 by heat and pressure, which deforms the head, and the waveguide antenna 7 is "pressed in" by the thermal crimping pins 2, resulting in a snap-fit ​​connection.

[0016] In Fig. 3a-d, various exemplary arrangements of the thermal crimping pins 2 of the radome 1 on the waveguide antenna 7 are shown in plan views of the waveguide antenna 7, respectively, without the radome 1 being shown for clarity. These arrangements should be understood as merely examples, and other arrangements and other numbers of thermal crimping pins 2 can also be used depending on the actual application and the available installation space. In Fig. 3a and b, according to the first embodiment (see the above description in relation to Fig. 1), the thermal crimping pins 2 are connected to the body of the waveguide antenna 7, in which the waveguide is also configured. Fig. 3a shows two thermal crimping pins 2 on opposite sides of the waveguide antenna 7, which are sufficient for a stable connection of the waveguide antenna 7 to the radome 1. Fig. 3b shows three thermal crimping pins 2 forming a triangle, which further improves the stability. In Figures 3c and d, according to the second embodiment (see above description in relation to Figure 2), a protrusion 9 is formed on the waveguide antenna 7 for each thermal crimping pin 2, and each thermal crimping pin 2 is connected to a corresponding protrusion 9. Figure 3c shows two protrusions 9 and two thermal crimping pins 2 on opposite sides of the waveguide antenna 7, and Figure 3d shows three protrusions 9 and three thermal crimping pins 2 forming a triangle.

Claims

1. A radar sensor comprising a waveguide antenna (7), a radome (1), a housing (3) to which the radome (1) is fixed, and a circuit board (4) on which the waveguide antenna (7) is positioned, characterized in that the waveguide antenna (7) and the radome (1) are connected to each other in a mating manner.

2. 2. The radar sensor according to claim 1, characterized in that the radome (1) has a pin (2) which extends through the waveguide antenna (7) and is connected to the waveguide antenna (7).

3. 3. The radar sensor according to claim 1, wherein the mating connection is achieved by a heat crimping process.

4. The radar sensor according to any one of claims 1 to 3, characterized in that the waveguide antenna (7) has at least one protrusion (9), and the mating connection is realized by the at least one protrusion (9).

5. 1. A method for manufacturing a radar sensor, comprising: Providing a waveguide antenna (7); Providing a radome (1); a step of matingly connecting the radome (1) and the waveguide antenna (7); assembling the radome-waveguide antenna assembly into a housing (3) of the radar sensor; The method according to claim 1, further comprising:

6. 6. The method of claim 5, wherein the mating connection is made by a heat crimping process.

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