Radar device for a vehicle

Abstract

Radar device (10) for a vehicle, comprising: - a tub-shaped housing (7) which can be closed by a housing cover (8), - a first printed circuit board (4) arranged in the housing (7) and positioned by means of contact elements (7d) relative to a housing base (7c) for receiving an antenna and high-frequency components, - a second printed circuit board (5) for accommodating low-frequency components, and - a shielding device (1) arranged between the two circuit boards (4, 5) and having an electromagnetic shielding property, - the shielding device (1) consists of two adjacent hood-shaped shields (2, 3) covering the first and second circuit boards (4, 5) and having spring-elastic properties in the direction perpendicular to the circuit boards, and - the shielding device (1) is designed to be supported in a spring-biased manner on the one hand against the second printed circuit board (4) fixed in position in the housing (7) and on the other hand against the first printed circuit board (5), the spring-loaded first printed circuit board (4) being held pressed against the contact elements (7d) of the housing (7), a spacer (3d) is provided between the shields (2, 3) of the shielding device (1), which spacer brings about mutual spring-elastic contact of the two shields (2, 3) in a direction perpendicular to the circuit board planes of the two circuit boards (4, 5).

Description

The invention relates to a radar device for a vehicle according to the preamble of claim 1.Radar devices for vehicles are known from the prior art and are used, for example, to determine a distance from vehicles traveling ahead.A radar device of the generic type is known from DE 10 2007 042 173 A1, in which two printed circuit boards, namely a printed circuit board with a radar antenna and high-frequency components (high-frequency printed circuit board) and a further printed circuit board with low-frequency components (low-frequency printed circuit board), are accommodated in a trough-shaped housing. The bottom of the trough-shaped housing is designed as a radome.The two printed circuit boards of this known radar device are connected to a carrier by means of screws and then inserted with this carrier into the housing, which is closed by a housing cover. The carrier for the two circuit boards consists of a frame part enclosing a shielding surface, the radome-side end face of which has a support surface for the first circuit board, wherein ribs formed on the shielding surface form chambers together with the shielding surface and the first circuit board. On the opposite side of the carrier, the further printed circuit board is inserted into the frame part and screwed to the carrier, so that at the same time a plug connection to the first printed circuit board can be produced via an aperture of the shielding surface. The first printed circuit board is also connected to the carrier via a screw connection.This carrier with the two printed circuit boards is inserted into the housing, so that the first printed circuit board rests on support posts which lie on the corner side of the housing and form a support plane, and the carrier can be screwed to further support posts. When the carrier is inserted into the housing, contact pins of a front-side plug, which contact pins are designed as press-in contacts, are pressed into corresponding connection bores on the second printed circuit board for electrical contacting.24 GHz or 77 GHz are used as radar frequencies for such radar devices, wherein the problem exists that the distance between the antenna arranged on the front side of the high-frequency printed circuit board and the trough base of the trough-shaped housing, which is designed as a radome, is critical to tolerances.Furthermore, the use of the contact pin press-fit technique for contacting the low-frequency printed circuit board via a connector plug in the direction perpendicular to the printed circuit board is likewise critical to tolerances on account of process specifications. Therefore, these two printed circuit boards arranged at a distance one above the other, i.e. the high-frequency printed circuit board and the low-frequency printed circuit board, must be positioned exactly with respect to one another in the vertical direction.In the known radar device according to DE 10 2007 042 173 A1, this is achieved in that the two printed circuit boards are fixed in the carrier by corresponding bearing planes and screwed to the carrier. However, it is disadvantageous that the bearing planes of the carrier must meet close tolerances with respect to one another. In order to also maintain an exact distance between the high-frequency printed circuit board carrying the antenna and the trough base of the trough-shaped housing formed with the radome, the support posts forming the support plane of the high-frequency printed circuit board or of the carrier must also be produced with tight tolerances.EP 2 034 328 A1 discloses a radar sensor in which two printed circuit boards which are electrically connected to one another are arranged in a releasable manner on a metallic carrier.JP H11153782 A describes a liquid crystal display device which is disposed in a case and fixed to a circuit board.Furthermore, DE 10 2005 033 592 A1 describes a carrier for receiving an antenna amplifier with a printed circuit board and latching means and spring means interacting therewith for fixing the printed circuit board to the carrier.Proceeding from this prior art, it is an object of the invention to specify a radar device of the type mentioned at the beginning, with which a defined distance between the radome of the radar device and the printed circuit board carrying the radar antenna is ensured and at the same time a defined position of the two printed circuit boards is ensured.This object is achieved by a radar device having the features of claim 1.Such a radar device for a vehicle, which comprises a trough-shaped housing closable by a housing cover, a first printed circuit board arranged in the housing and positioned by means of bearing elements relative to a housing base for receiving an antenna and high-frequency components, a second printed circuit board for receiving low-frequency components, and a shielding device arranged between the two printed circuit boards and having an electromagnetically shielding property, is distinguished according to the invention in that the shielding device consists of two hood-shaped shields lying against one another and covering the first and second printed circuit boards and having spring-elastic properties in a direction perpendicular to the printed circuit boards, and the shielding device is designed to be supported in a spring-biased manner on the one hand against the second printed circuit board fixed in position in the housing and on the other hand against the first printed circuit board, wherein the first printed circuit board subjected to spring force is held pressed against the bearing elements of the housing.The problems listed above are solved according to the invention in a surprising and simple manner and thus cost-effectively in that as shielding device, shields which lie resiliently against one another are arranged between the first printed circuit board carrying the antenna, that is to say the high-frequency printed circuit board and the second printed circuit board, that is to say the low-frequency printed circuit board, as a result of which tolerance compensation takes place between these two printed circuit boards, but a precisely defined distance from the housing base of the housing, which is preferably designed as a radome, is maintained.Furthermore, the position of the second printed circuit board, i.e. of the low-frequency printed circuit board, is also exactly defined, since this is fixed in position with respect to the housing and, as a result, the tolerance requirements for the contact pins of a plug designed as press-fit contacts for the electrical contacting of the second printed circuit board are also fulfilled. In this case, the housing has, according to a development, a contact surface for fixing the position of the second printed circuit board, which contact surface is overlapped by the shielding device in the non-spring-biased state of the latter. This allows simple and process-safe mounting of the radar device, since when the housing cover is mounted on the trough-shaped housing, the second printed circuit board is pressed against its contact surface and is thereby brought into its spring-biased state via the contact with the shielding device.According to the invention, in order to realize the spring-elastic property of the shielding device, a spacer is provided between the shields of the shielding device, which spacer brings about a mutual spring-elastic contact of the two shields in the direction perpendicular to the printed circuit board planes of the two printed circuit boards.In one embodiment of the invention, one of the shields has a substantially central elevation as a spacer between the two printed circuit boards. The integration of the spacer into one of the two shields facilitates the production of the shielding device. For this purpose, the elevation is preferably designed in the form of a trough with a substantially planar base.Furthermore, it is particularly advantageous if, according to a further embodiment of the invention, at least one shield has two protruding fixing knobs which engage in fixing openings of the adjacent shield for the relative positional fixing of the two shields. This facilitates the mounting of the radar device according to the invention, in particular the insertion of the two shields into the housing. Preferably, the fixing openings are arranged in the region of the central elevation.Advantageously, according to one embodiment of the invention, the edge of a shield serving for the surface connection with the printed circuit board is formed in such a way that the printed circuit board is surrounded on the edge side by this edge.Furthermore, according to one embodiment of the invention, it is provided that the two shields have congruent openings for realizing a plug connection. Thus, during the assembly of the radar device, the two printed circuit boards can be connected to one another via a plug and a socket. In this case, the opening of the shield covering the first printed circuit board is preferably formed with spring tabs acting in a spring-elastic manner in the direction of the first printed circuit board. Thus, in this region of the plug connection, an EMC shielding can be realized by means of an RF tube which is held by means of these spring tabs.A particularly cost-effective production of the shielding device is achieved according to the development in that the shields are each designed as a deep-drawn sheet with a circumferential wall and a projecting edge as a bearing surface for the printed circuit board. In this case, the elevation is preferably also produced as a spacer in the plane of the shield with a circular cross section by deep drawing.A development of the invention which simplifies the assembly particularly is achieved in that the two shields are connected in a materially integral manner in the region of the central elevation. This is preferably implemented by means of a clinching connection, also called a Tox ©- connection.As already explained above, the housing base is designed as a radome according to the refinement.The invention is described in detail below on the basis of an exemplary embodiment with reference to the appended figures. The following are shown: FIG. 1 is an exploded view of a radar device according to the invention, FIG. 2 is a perspective view of a shielding device of the radar device according to FIG. 1 , FIG. 3 shows an exploded view of the two shields of the shielding device according to FIG. 2, FIG. 4 is a plan view of the shielding device according to FIG. 2, FIG. 5 shows a sectional illustration according to section A-A of the shielding device according to FIG. 4, FIG. 6 shows a perspective illustration of the radar device according to FIG. 1 in the assembled state, and FIG. 7 shows a sectional illustration according to section B-B of the radar device according to FIG. 6.The radar device 10 shown fully assembled in FIG. 6 comprises, according to FIG. 1, a trough-shaped housing 7 with side walls 7 aand 7 bconnected via a housing base 7 cand a housing cover 8. Therefore, in the following, the first printed circuit board 4 is also referred to as a high-frequency printed circuit board and the second printed circuit board 5 is also referred to as a low-frequency printed circuit board. The high-frequency printed circuit board 4 carries a radar antenna and a shield 6 on the housing base side, since high-frequency components are likewise arranged on this side of the first printed circuit board 4. The housing base 7 cof the housing 7 is designed as a radome.The parallel side walls 7a of the housing 7 are formed as longitudinal side walls and the parallel side walls 7b thereof as transverse side walls. A plug socket 9 is formed on a transverse side wall 7b, the plug contacts of which are guided into the housing 7 and terminate there in press-fit pins 9a bent at right angles. This region with the press-in pins 9a is separated from the remaining region of the housing by a further transverse side wall 7b' running parallel to the transverse side wall 7b having the plug socket. Furthermore, post-like contact elements 7 dare integrally formed in the edge regions of the housing base 7 cof the housing 7, each of which elements forms a contact surface for the first printed circuit board 4 to be inserted into this housing 7.According to FIGS. 2 and 3, the shielding device 1 comprises two hood-shaped shields 2 and 3, each of which consists of a side wall 2 aand 3 acirculatory around a shielding base 2 cand 3 cand a projecting edge 2 band 3 bof the side wall 2 aand 3 a, respectively. This projecting edge 2 band 3 bof the shielding 2 and 3 forms a bearing surface against which the printed circuit board 4 and 5 according to FIG. 7 bears on the edge side in the assembled state of the radar device 10, such that the high-frequency and low-frequency components HF and NF arranged on the printed circuit boards 4 and 5 are covered and therefore shielded electromagnetically.In order to realize a spring-elastic property between the edges 2 band 3 bof the shields 2 and 3 which respectively form a bearing surface for the printed circuit boards 4 and 5, these shields 2 and 3 lie at a distance against one another via their shielding bases 2 cand 3 c, wherein, in order to realize a distance a according to FIG. 5, the shielding base 3 ccomprises a centrally arranged elevation 3 das a spacer, as can be seen in particular from the sectional illustration according to FIG. 5. According to FIG. 4, this elevation 3 dformed in the direction of the shield 2 is formed with a circular cross section with a planar contact surface 3 f, against which the shielding base 3 cof the shield 3 bears in a surface-fitting manner.Since the two shielding plates 2 cand 3 care only partially in contact via this elevation 3 b, the two shielding plates 2 cand 3 cmay elastically swing out perpendicularly to their planes when a pressure is exerted on the edges 2 band 3 bof the shields 2 and 3.For the mutual fixing of the two screens 2 and 3, the screen base 2c has two fixing knobs 2d spaced apart at a short distance, which engage in corresponding fixing openings 3f arranged in the region of the elevation 3d and formed as dome-like protuberances.Furthermore, the two shields 2 and 3 each have an opening 2 eand 3 g, respectively, which serve to electrically connect the two printed circuit boards 2 and 3 to one another via a plug connection. In order to realize an EMC shielding in this region of the plug connection as well, an RF tube (not shown in the figures) is provided, which is held by means of spring tabs 2 fformed at the edge of the opening 2 f.The two shields 2 and 3 are produced as deep-drawn sheet metal parts. Thus, with a deep-drawing process, the elevation 3 dis also produced as a spacer of the shield 3 and its dome-like fixing openings 3 e; in the same way, the shield 2 is produced together with the fixing knobs 2 bin a deep-drawing process.The two shields 2 and 3 of the shielding device 1 are connected to one another in a force-fitting manner via the fixing knobs 2 dand the fixing openings 3 e. Such a connection can be realized, for example, by means of a clinching connection, also called a Tox ©- connection.The mounting of the radar device 10 begins by initially inserting the high-frequency printed circuit board 4 into the housing 7, so that it flies onto the contact elements 7 darranged in the housing 7. This first printed circuit board 4 has a length in the direction of the longitudinal side walls 7a, so that the press-fit pins 9a of the plug socket 9 are guided past this first printed circuit board 4 and therefore this first printed circuit board 4 can be inserted in this region into the space formed by the further transverse side wall 7b' and the side walls 7a and 7b, as can be seen from FIG. 7.Subsequently, the shielding device 1 with the connected shields 2 and 3 is placed on this first printed circuit board 2, so that the edges 2 bof the shield 2 rest circumferentially on this first printed circuit board 4 on the edge side. This shielding device 1 with the two shields 2 and 3 is dimensioned such that the edge 3b serving as a bearing surface for the second printed circuit board 5 protrudes slightly beyond a bearing surface 7e arranged on the side walls 7a and 7b or 7b' of the housing 7.The low-frequency printed circuit board 5 is now placed on the edge 3b of the shield 3 serving as the bearing surface, wherein this printed circuit board 5 extends with an edge region 5a over the region separated from the transverse side wall 7b', so that this edge region 5a of the second printed circuit board 5, which edge region has the press-in openings for the press-in pins 9a, is not covered by this shield 3 and, when this low-frequency printed circuit board 5 is inserted into the housing 7, the press-in pins 9a are partially pressed into the press-in openings of the second printed circuit board 5 lying in the region 5a. This second printed circuit board 5 is thus longer by this region 5 acompared to the first printed circuit board 4. In this state, a small distance is obtained between this second printed circuit board 5 and the circumferential contact surface 7e on the side walls 7a and 7b or 7b' of the housing 7.To close the housing 7, the housing cover 8 is placed on the second printed circuit board 5 or the side walls 7 aand 7 bof the housing 7 and screwed to the housing 7 on the corner side by means of screws 8 c, so that, according to FIG. 7, the second printed circuit board 5 is thereby pressed by a circumferential web 8 aon the bearing plane 7 eand fixed in this position, and at the same time the shielding device 1 is also compressed while generating a spring force, since the first printed circuit board 4 bears against the bearing elements 7 dand thus serves as a counter bearing. In addition, during this mounting process, the press-fit pins 9 aare also pressed into the press-fit openings region 5 aof the second printed circuit board 5 into their end position.Thus, in the closed state of the housing 7, the shielding device 1 is in the prestressed state, i.e. when the second printed circuit board 5 bears against the contact surface 7 ebased on the screw connection of the housing cover 8 to the housing 7, with the result that the first printed circuit board 4 is thereby pressed against the contact elements 7 d.The radar device 10 mounted in this manner is mounted to the vehicle body of a vehicle via mounting screws 8 dapplied to the housing cover 8.The housing 7 can be designed as a base material housing, wherein the housing cover 8 is realized in metallic or co-metallic fashion, so that even in the mounted state low-frequency components arranged on the housing-side printed circuit board side of the second printed circuit board 5 are also shielded electromagnetically. On its outer side, such a housing cover 8 is equipped with cooling ribs 8b for the purpose of better heat dissipation.Reference numerals denote reference numerals1 Shielding device 2 Shielding of the shielding device 2 a Sidewall of the shielding 2 2 b Edge of the shielding 2 2 c Shielding base of the shielding 2 2 d Fixing nub 2 e Opening in the shielding 2 2 f Spring tabs at the opening 2 d 3 Shielding of the shielding device 3 a Sidewall of the shielding 3 3 b Edge of the shielding 3 3 c Shielding base of the shielding 3 3 d Abstandshalter, protrusion 3 e Opening 3 f Opening in the shielding 3 4 First printed circuit board, high-frequency printed circuit board 5 Second printed circuit board, Low-frequency printed circuit board 5a Edge region of the printed circuit board 5 with press-in openings 6 Shield 7 Housing of the radar device 7a Side wall of the housing 7 7b Side wall of the housing 7 7c Housing base of the housing 7 7d Contact elements of the housing 7 7e Contact surface of the housing 7 8 Housing cover of the housing 7 8a Circumferential web of the housing cover 8 8b Cooling ribs of the housing cover 8 8c Screw 8d Mounting screws 9 Plug socket 9a Press-in pins of the plug socket 9 10 Radar device

Claims

Radar device (10) for a vehicle, comprising: - a trough-shaped housing (7) which can be closed by a housing cover (8), - a first printed circuit board (4) which is arranged in the housing (7) and is positioned with respect to a housing base (7c) by means of bearing elements (7d) and is intended to accommodate an antenna and high-frequency components, - a second printed circuit board (5) is intended to accommodate low-frequency components, and - a shielding device (1) which is arranged between the two printed circuit boards (4, 5) and has an electromagnetically shielding property, - the shielding device (1) consists of two hood-shaped shields (2, 3) which lie against one another and cover the first and second printed circuit boards (4, 5) and have spring-elastic properties which are perpendicular to the printed circuit boards, and - the shielding device (1) is designed to be designed to be able to cover the first and second printed circuit boards, The second circuit board (4) which is positionally fixed in the housing (7) is supported on the one hand in a spring-biased manner and on the other hand against the first circuit board (5), wherein the first circuit board (4) which is subjected to spring force is held pressed against the bearing elements (7d) of the housing (7), a spacer (3d) is provided between the shields (2, 3) of the shielding device (1), which spacer brings about mutual spring-elastic bearing of the two shields (2, 3) in a direction perpendicular to the circuit board planes of the two circuit boards (4, 5).Radar device (10) according to Claim 1, characterized in that the housing (7) has a contact surface (7e) for fixing the position of the second printed circuit board (5), which contact surface is overlapped by the shielding device (1) in the non-spring-biased state of the latter.Radar device (10) according to Claim 2, characterized in that the housing cover (8) is designed to close the housing (7) with the second printed circuit board (5) resting against its bearing surface (7e).Radar device (10) according to one of the preceding claims, characterized in that one of the shields (3) has a substantially central elevation (3d) as a spacer between the two printed circuit boards (4, 5).Radar device (10) according to one of the preceding claims, characterized in that the elevation (3d) is designed in the form of a trough with a substantially planar base.Radar device (10) according to one of the preceding claims, characterized in that a shield (2) has at least two protruding fixing knobs (2d), which engage in fixing openings (3e) of the adjacent shield (3) for the relative positional fixing of the two shields (2, 3).Radar device (10) according to Claim 6, characterized in that the fixing openings (3e) are arranged in the region of the central elevation (3d).Radar device (10) according to one of the preceding claims, characterized in that the edge (2b, 3b) of a shield (2, 3) serving for the surface connection to the printed circuit board (4, 5) is designed to surround the printed circuit board (4, 5) on the edge side.Radar device (10) according to one of the preceding claims, characterized in that the two shields (2, 3) have congruent openings (2e, 3f) for realizing a plug connection.Radar device (10) according to Claim 9, characterized in that the opening (2e) of the shield (2) shielding the first printed circuit board (4) is formed with spring tabs (2f) which act resiliently in the direction of the first printed circuit board (4).Radar device (10) according to one of the preceding claims, characterized in that the screens (2, 3) are each designed as a deep-drawn sheet with a circumferential wall (2a, 3a) and a projecting edge (2b, 3b) as a bearing surface for the printed circuit board (4, 5).Radar device (10) according to Claim 11, characterized in that the elevation (3d) with a circular cross section in the plane of the shield (3) is produced by deep drawing.Radar device (10) according to one of the preceding claims, characterized in that the two shields (2, 3) are connected in a materially integral manner in the region of the central elevation (3d).Radar device (10) according to Claim 11, characterized in that the two shields (2, 3) are connected by means of a clinching connection.Radar device (10) according to one of the preceding claims, characterized in that the housing base (7c) is designed as a radome.

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