Radar system

Abstract

The invention relates to a radar system (1) comprising electronics (2) for transmitting and / or receiving radar signals and an antenna element (3), the antenna element (3) being designed as a plastic body into which a channel (4) having a metallized channel wall is introduced, the channel (4) forming a waveguide, and a heat-conducting element (5) being introduced into the antenna element (3).

Description

Technical Field

[0001] The invention relates to a radar system comprising electronics for transmitting and / or receiving radar signals and an antenna element, wherein the antenna element is designed as a plastic body into which a channel with metallized channel walls is introduced, wherein the channel forms a waveguide. Background Art

[0002] Such a radar system is known, for example, from US2021 / 0183797 A1. Radar systems of the type mentioned at the beginning are usually used in motor vehicles and form a component of the driver assistance system there. To this end, the radar system detects the surrounding environment and can realize the automatic reaction of the motor vehicle or at least one information of the driver according to the detected data, especially information in the form of a warning. Thus, on the one hand, it is feasible to adjust the speed of the vehicle to a speed preset by the driver when the traffic situation permits, wherein the speed is automatically matched to the traffic situation. In an emergency situation detected by the radar system, such as an emergency situation caused by an unexpected lane change of other vehicles, automatic emergency braking will be prompted. In driver assistance systems and automatic driving systems, radar systems are usually combined with other sensors, such as wheel sensors and camera sensors. Compared with other systems, the radar system has the following advantages here: the radar system is also reliable under bad weather conditions. In addition, it is feasible that in addition to detecting the distance from the detected vehicle and object, the relative speed to other vehicles can also be determined by utilizing the Doppler effect.

[0003] In radar systems, antenna elements form central elements that decisively influence the functionality of the radar system. It is known that antenna elements consist of a one-piece or multi-piece plastic body, wherein a channel is introduced into the antenna element and wherein the channel walls of the channel are configured to be electrically conductive, the channel forming a waveguide. The antenna element is operatively connected to electronics for transmitting and / or receiving radar signals.

[0004] The electronic components are usually microchips in the form of radio frequency chips arranged on a circuit board. The problem here is that no significant heat is discharged during the operation of the radar system, which is particularly due to the need to provide electromagnetic waves in the spectrum that is common to radar waves with a sufficient range. Depending on the design of the radar system, the heat discharge can be several watts, which is accompanied by a high thermal load on a small space, especially in compact radar systems. Antenna elements made of plastic are only suitable to a certain extent for dissipating heat from the system in a suitable manner due to the low thermal conductivity. Summary of the invention

[0005] The invention is based on the object of providing a radar system having improved thermal properties.

[0006] This object is achieved with the features of claim 1. The dependent claims relate to advantageous embodiments.

[0007] The radar system according to the invention comprises an electronic component for transmitting and / or receiving radar signals and an antenna element, wherein the antenna element is designed as a plastic body, into which a channel with conductively configured channel walls is introduced, wherein the channel forms a waveguide, and wherein a heat conducting element is introduced into the antenna element.

[0008] According to the invention, the antenna element has thermal properties in addition to its electromagnetic properties, and heat can be transferred through the antenna element, but it can also be transferred out of the antenna element. For example, it is conceivable that the antenna element transfers heat introduced during production via a heat-conducting element. As a result, a higher heat input is possible during production on the one hand, and a shortened cooling time is also possible on the other hand. It is also possible to form a compact radar system that is robust and can be operated over a long period of time. The improved thermal properties of the antenna element make the temperature in the antenna element uniform. In addition, the heat dissipation of the chip that transmits and receives the radar radiation is also improved, so that the measurement accuracy and the transmission power of the radar system are improved.

[0009] In multi-part antenna elements, the individual elements are usually connected to one another via a welding process. The heat input is usually carried out via an air flow applied to the antenna element on both sides. The heat conducting element improves the transport of the hot air and is improved in such a way that the heat can be better transported into the interior of the element. This can speed up the joining process and simultaneously produce a welded connection with improved quality.

[0010] The heat conducting element can include recesses and / or perforations introduced into the plastic body. In this case, the recesses and / or perforations are introduced into the plastic body independently of the channel forming the waveguide. As plastics for the antenna element, suitable high-temperature-resistant polymers are in particular polyphenylene sulfide (PPS), polyetherimide (PEI), polyphenylene ether (PPE), polyamide (PA), liquid crystal polymer (LCP), polycarbonate (PC), polyphthalamide (PPA), polyetheretherketone (PEEK) or mixtures of the aforementioned polymers.

[0011] Preferably, the area of ​​the antenna element is free of notches and / or perforations associated with corresponding areas of the microchip or circuit board.

[0012] The thermal conductivity can be improved by coating the recesses and / or perforations with a thermally conductive material. Advantageous materials for the coating are, for example, metals such as nickel, chromium, aluminum, copper, tin, zinc, silver or gold. These materials are also suitable for the conductive configuration of the channel wall. The metal coating can be single-layer or multi-layer. The heat conduction is carried out parallel to the material of the antenna element via the coating of the recesses and / or perforations, so that the thermal conductivity is improved overall. Typical thermal conductivity coefficients for plastics are, for example, approximately 0.3 W / m×K, and typical thermal conductivity coefficients for copper are approximately 300 W / m×K.

[0013] The metal coating can be applied in particular by galvanic coating.

[0014] Ceramic coatings are also conceivable, for example based on aluminum oxide. The ceramic coating can be applied via a vacuum method.

[0015] The layer thickness of the coating is preferably between 0.5 μm and 40 μm. Such a coating is cost-effective and has good thermal conductivity.

[0016] The recess can be formed in the form of a blind hole or a through hole, for example. It is conceivable that the recess is designed in a circular shape. However, it is particularly preferred that the recess or perforation has a configuration different from a circular shape. It is advantageous that the side surface of the recess or perforation is enlarged, which in turn increases the thermal conductivity. This is particularly applicable when the wall of the recess and / or perforation is coated with a heat-conducting material. For example, the recess or perforation can be formed in a plum blossom shape when viewed from above. In order to improve the cooling performance, the recess and / or perforation preferably does not accommodate objects, in particular does not accommodate retaining mechanisms, such as screws, etc.

[0017] The recess and / or the perforation can form a channel. Here, the recess extends into the plastic body or passes through the plastic body in the case of the perforation. It is thus possible to conduct heat from the radar system through the plastic body or to transfer heat to other components of the radar system via the plastic body.

[0018] The heat flow through the antenna element increases with the number of recesses and / or perforations per unit area. Preferably, the unit area here refers to the surface of the antenna element facing the electronic component. It has proven to be advantageous to have a maximum heat flux per cm2. 2 The surface facing the electronic device is provided with between 10 and 50 notches and / or perforations. 2 A good heat flow is already obtained with the presence of three recesses and / or perforations. The recesses and perforations can have different geometries, wherein the geometric configuration and the surface that is available for heat transfer, in particular, influence the heat transfer. In particular, the recesses can be arranged in the region of the surface facing the electronic component. The perforations are preferably designed so that they penetrate the antenna element.

[0019] Depending on the configuration of the recesses and / or perforations, it may be sufficient if the recesses or perforations are elongated and have a length of more than 10 mm, for each cm 2 The surface facing the electronic device is provided with between 3 and 15 notches and / or perforations. In the case of a meandering structure, for each cm 2 1 to 10 of the surfaces facing the electronic component may be sufficient. A meandering structure is particularly advantageous when the recesses are close to the surface. Overall, the described design provides good heat conduction through the antenna element, in particular during the production and the bonding processes associated therewith. At the same time, the functionality of the antenna element is not impaired.

[0020] The heat conducting element may include recesses in the form of a surface structuring. For example, a surface structuring in the form of ribs or grooves may be introduced into the surface of the plastic body, wherein the surface structure increases the surface of the plastic body, which in turn is accompanied by an increase in the thermal conductivity. It is particularly conceivable here to introduce the surface structuring into regions of the plastic body that are not associated with the channel forming the waveguide. If for every cm 2 If the surface of the electronic device facing the electronic device is provided with 3 to 15 structures in the form of ribs or grooves, an advantageous heat dissipation via the surface structure is obtained. This applies in particular when the structure is elongated and has a length of more than 10 mm. In the case of a meandering structure, for every cm 2 For the surface facing the electronics, 1 to 10 notches may be sufficient.

[0021] The heat conductor can be embedded in the antenna element. Compared to the material of the plastic body, the heat conductor has a higher thermal conductivity. As a result, heat can be transferred to the outside particularly quickly and effectively via the heat conductor.

[0022] The heat conductor can be made of a metallic material. In this context, it is particularly conceivable to design the heat conductor as a shaped part, for example in the form of a cylindrical element such as a sleeve or a metal wire. It is also conceivable to design the heat conductor in the form of a metal plate. As materials for the heat conductor, heat conducting materials made of metallic materials such as copper or aluminum are particularly suitable.

[0023] The heat conductor can be made of a heat-conducting plastic. In this case, the heat conductor is designed such that the thermal conductivity is greater than the thermal conductivity of the material of the plastic body. In this context, it is particularly conceivable to form the heat conductor in the form of a flexible conductor track or as a pre-injection molded product. Although the heat conductor has a lower thermal conductivity than a heat conductor made of a metallic material, it is advantageous that heat conductors with complex geometries can be realized from plastic. This is particularly advantageous in conjunction with complex waveguide structures. Preferably, the heat-conducting plastic has a thermal conductivity of at least 1 W / m×K.

[0024] The antenna element can be constructed in multiple layers. In this embodiment, it is possible to form particularly complex channels and / or to provide heat-conducting elements in the plastic body. It is also conceivable that the layers of the multilayer antenna element have different thermal conductivity properties. In this context, it is particularly advantageous if the layer facing the component or the circuit board has a higher thermal conductivity than the other layers. For this purpose, the layer facing the component or the circuit board can be provided with a thicker coating, in particular a thicker metal coating.

[0025] The heat conducting element can comprise an applied, for example printed structure. For example, it is conceivable that a heat conducting material is printed or bonded to the plastic body on the outside.

[0026] The antenna element can be covered by a radome. The radome protects the antenna element from external influences. The radome can form a structural unit with the antenna element. In the described design, the waveguide is closed on the side from which the electromagnetic radiation emerges and the electromagnetic radiation is conducted through by correspondingly modifying the coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Some design solutions of the radar system according to the present invention are described in detail below with reference to the accompanying drawings. The accompanying drawings schematically show:

[0028] Figure 1 showing a cross section of a radar system;

[0029] Figure 2 A perspective view from obliquely above showing an antenna element;

[0030] Figure 3 A perspective view from obliquely below showing an antenna element;

[0031] FIG4 shows a top view of the antenna element;

[0032] FIG. 5 shows a graph illustrating thermal conductivity as a function of the number of thermally conductive elements. DETAILED DESCRIPTION

[0033] The drawing shows a radar system 1 which is a component of a driver assistance system of a vehicle. The radar system 1 comprises an electronic component 2 for transmitting and / or receiving radar signals and an antenna element 3 arranged on the electronic component 2. The component 2 is designed in the form of an integrated circuit and is arranged on a printed circuit board 6. The antenna element 3 is connected to the component 2 in a material-bonded manner via an adhesive connection.

[0034] In an alternative embodiment, the electronic component 2 is arranged on one main side of the printed circuit board 6 , and the antenna element 3 is arranged on the other main side. In this case, the printed circuit board 6 is configured to allow electromagnetic radiation to pass between the component 2 and the antenna element 3 .

[0035] The antenna element 3 is designed as a plastic body made of polyetheretherketone (PEEK), wherein the plastic body forming the antenna element 3 is designed in multiple layers and consists of a plurality of plates stacked one above the other. A plurality of channels 4 with metallized channel walls are introduced into the plastic body, wherein the channels 4 form a waveguide. The waveguide is operatively connected to the transmitting / receiving unit of the electronic component 2. The antenna element is covered by a radome.

[0036] A heat-conducting element 5 is introduced into the antenna element 3, which in the present design comprises a recess and a perforation. The recess and the perforation form a channel. Here, the recess is formed on the side facing the component 2, so that a surface structuring is formed there. A heat conductor is embedded in the recess, which consists of a metallic material, currently aluminum. In an alternative design, the heat conductor consists of a heat-conducting plastic. In another alternative design, the heat-conducting element 5 comprises a printed structure.

[0037] Figure 1 The radar system 1 described above is shown in section. Figure 2 The antenna element 3 is shown in a perspective view obliquely from above, and Figure 3 The antenna element 3 is shown in a perspective view obliquely from below, which has a heat-conducting element 5 in the form of a meandering aperture and cutout. The walls of the cutout and the aperture are coated with a heat-conducting material.

[0038] FIG. 4 shows a top view of a design of an antenna element 3 in which the heat conducting element 5 is designed in the form of a through-hole through the antenna element 3. In this design, the cross-sectional shape of the through-hole is quincunx-shaped. In this design, with respect to the cross-sectional area of ​​the recess, which represents the space requirement of the through-hole, a larger area of ​​the channel wall is obtained, thereby resulting in an improvement in the heat conduction.

[0039] The channel wall is provided with a coating made of a metallic material, in the present case aluminum. The layer thickness of the coating is 20 μm. In the present embodiment, for each cm 2 On the surface of the antenna element facing the electronic component 2, 24 recesses are introduced into the antenna element.

[0040] FIG. 5 shows a diagram of a simulation calculation, from which it can be seen that the heat flow increases with the number of perforations. The number of slits from 0 to 12 is plotted on the abscissa and the heat flow from 0 watt to 3 watts at 40 Kelvin is plotted on the ordinate. The calculation is based on the fact that elongated perforations with a length of 23 mm and a width of 1.2 mm are introduced into a cube made of polyamide with a side length of 25 mm. The surface of the cube is provided with a gold coating with a layer thickness of 10 μm. A temperature difference is generated in the direction of the perforation, which causes a heat flow in the same direction.

Claims

1. A radar system (1), comprising an electronic component (2) for transmitting and / or receiving radar signals and an antenna element (3), wherein the antenna element (3) is designed as a plastic body, into which a channel (4) with metallized channel walls is introduced, wherein the channel (4) forms a waveguide, It is characterized in that A heat conducting element (5) is introduced into the antenna element (3).

2. The radar system according to claim 1, It is characterized in that The heat conducting element (5) comprises recesses and / or perforations.

3. The radar system according to claim 2, It is characterized in that The recesses and / or perforations form channels.

4. The radar system according to claim 2 or 3, It is characterized in that The recesses and / or the perforations are provided with a heat-conducting coating.

5. The radar system according to any one of claims 2 to 4, It is characterized in that For each cm 2 The surface facing the electronic device (2) is provided with between 1 and 50, in particular between 3 and 15, recesses and / or perforations.

6. The radar system according to claim 4 or 5, It is characterized in that The coating includes a metallic material.

7. The radar system according to any one of claims 4 to 6, It is characterized in that The layer thickness of the coating is between 0.5 μm and 40 μm.

8. The radar system according to any one of claims 4 to 7, It is characterized in that The coating is designed as a galvanic coating.

9. The radar system according to any one of claims 1 to 8, It is characterized in that The heat conducting element (5) comprises a surface structuring.

10. The radar system according to any one of claims 1 to 9, It is characterized in that The heat conducting element (5) comprises a heat conductor embedded in the antenna element (3).

11. The radar system according to claim 10, It is characterized in that The heat conductor is made of metal material.

12. The radar system according to claim 10 or 11, It is characterized in that The heat conductor is made of heat-conducting plastic.

13. The radar system according to any one of claims 1 to 12, characterized in that The antenna element (3) is constructed in multiple layers.

14. The radar system according to claim 13, It is characterized in that The layers associated with the device (2) have a higher thermal conductivity than the remaining layers.

15. The radar system according to any one of claims 1 to 14, It is characterized in that The heat-conducting element (5) comprises a printed structure.

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