DE102024105009B3 - motor vehicle with an underrun protection - Google Patents

Abstract

A motor vehicle (100) having an underrun protection (1) is proposed, wherein the underrun protection (1) has an EMC shield (2).

Description

The present invention relates to a motor vehicle with an underrun protection.

Modern motor vehicles have a large number of electrical and electronic components. In particular, motor vehicles with electric drive units, such as hybrid vehicles or electric vehicles, have powerful electric motors, extremely robust power electronics and HV batteries.

Electrical and electronic components emit electrical or electromagnetic fields due to their design. To ensure that these emitted electrical or electromagnetic fields do not interfere with other components or that the electrical or electronic component itself is not interfered with by fields from other components, measures are prescribed that lead to what is known as electromagnetic compatibility of the components. Electromagnetic compatibility, or EMC for short, is defined in the European EMC Directive 2014/30/EU as follows: "the ability of an equipment to operate satisfactorily in its electromagnetic environment without causing electromagnetic interference that would be unacceptable for other equipment in the same environment."

In order to ensure the required electromagnetic compatibility, electrical and electronic components are encased in shielding housings, for example.

With HV batteries in motor vehicles, special attention is paid to safety in the event of a thermal event. A thermal event can, for example, be triggered by a short circuit in the HV battery caused by mechanical impact, such as an accident. The short circuit in the HV battery generates a lot of heat in the HV battery, which leads to flammable gases being expelled from the electrodes of the HV battery. In order to discharge these flammable and hot gases from the HV battery in a controlled manner, a so-called cell vent is typically provided. A cell vent is an opening in the HV battery which opens in the event of excess pressure in a cell of the HV battery and through which the excess pressure can be relieved. If a thermal event causes the cell vent to open, the flammable gases must be discharged from the HV battery through the cell vent. Openings in the housing of the HV battery are typically provided for this purpose.

One problem arises from the fact that, on the one hand, openings must be provided in the housing to discharge the flammable gases from the housing of the HV battery and, on the other hand, the housing should be as closed as possible for electromagnetic shielding.

From the genre-defining publication US 2009 / 0 242 299 A1 and the JP 2016 - 41 586 A A vehicle with an underrun protection and a HV battery is known. The underrun protection has EMC shielding. The publication US 2014 / 0 329 125 A1 shows a vehicle with an underrun protection which has an EMC shield. This is indirectly connected via the body to a housing of an HV battery. From the publication DE 10 2021 005 538 A1 A vehicle HV battery is known whose EMC shielding is permeable to venting gases.

It is an object of the present invention to provide a motor vehicle which does not have the aforementioned disadvantages of the prior art, but offers shielding for achieving electromagnetic compatibility without placing design requirements on the components which relate to electromagnetic compatibility.

This object is achieved by a motor vehicle according to claim 1.

The motor vehicle according to the invention has an underrun protection. The underrun protection is a part on the floor of the motor vehicle which protects components of the motor vehicle from damage caused by contact with the ground on which the motor vehicle is driven. According to the invention, the underrun protection has EMC shielding. This advantageously makes it possible to electromagnetically shield the motor vehicle downwards using the underrun protection so that components in the motor vehicle in this direction meet the requirements relating to electromagnetic compatibility. The outsourcing of the EMC shielding from the electrical and/or electronic components of the motor vehicle to the underrun protection of the motor vehicle allows a high degree of flexibility in the design of the electrical or electronic components.

Advantageous embodiments and further developments of the invention can be found in the subclaims and the description with reference to the drawings.

According to the invention, the motor vehicle has a HV battery, wherein the EMC shielding is arranged below the HV battery. net. In this case, electromagnetic compatibility of the HV battery as an electrical component of the motor vehicle is advantageously ensured by the EMC shielding of the underrun protection of the motor vehicle. This makes it possible to design the housing of the HV battery in such a way that it meets the design requirements without being restricted by the provision of EMC shielding. The HV battery is preferably a traction battery of the motor vehicle. The motor vehicle is intended in particular as an electric vehicle or as a hybrid vehicle.

According to a further preferred embodiment of the present invention, the HV battery is provided with a base plate. At least one opening for degassing the HV battery is provided in the base plate. This advantageously makes it possible to discharge hot and flammable gases, which are expelled from the electrodes of the HV battery, from the housing of the HV battery in a controlled manner in the event of a thermal event. It is conceivable for the base plate to include a cooling plate for cooling the HV battery. Using the base plate to cool the HV battery enables the HV battery to be designed in a space-saving manner. It is thus advantageously possible to cool with the base plate, i.e. to provide only one element for this purpose instead of the base plate and cooling plate. The EMC shielding in the underrun protection ensures that the electromagnetic compatibility of the HV battery is still guaranteed despite the openings in the base plate of the HV battery, i.e. in the housing of the HV battery.

Preferably, the EMC shielding comprises a conductive layer of the underrun protection. The conductive layer in the sense of the present invention is an electrically conductive layer and can be provided, for example, by using metallic components in the conductive layer. Because the EMC shielding only comprises a conductive layer of the underrun protection, the underrun protection does not have to be completely conductive, which leads to weight savings. It is conceivable that the conductive layer is not arranged over the entire surface of the underrun protection, but that the conductive layer is only arranged in the area of the underrun protection that is below the HV battery.

Furthermore, it is preferably provided that the conductive layer comprises a conductive foil and/or a preferably fine-meshed conductive grid and/or a metal-deposited layer. This makes it possible in an advantageous manner to provide highly effective EMC shielding in the underrun protection in a very simple construction. Inserting a conductive foil, a preferably fine-meshed conductive grid or a metal-deposited layer is structurally simple and inexpensive. A grid is fine-meshed in the sense of the present invention if the mesh size is less than 2 cm.

According to a further preferred embodiment of the present invention, it is provided that the conductive layer is arranged between an upper layer of the underrun protection and a lower layer of the underrun protection. This advantageously makes it possible to protect the EMC shielding from mechanical and chemical influences and thus to ensure good electromagnetic compatibility in the long term. It is preferably provided that the upper layer and/or the lower layer is a fiber composite. A fiber composite is typically highly stable and comparatively light. It is also conceivable that the upper layer and/or the lower layer are laminates, i.e. either laminated together from at least several layers and/or at least laminated onto the EMC shielding.

It is also conceivable that a core layer is arranged between the lower layer and the conductive layer. This provides greater stability and thus greater mechanical resilience of the underrun protection. The core layer can be made of PU, i.e. polyurethane, or LFI-PUR, for example. For a core layer made of LFI-PUR, glass fibers are cut and wetted with liquid polyurethane. The wetted glass fibers are formed into the core layer under pressure. This has the advantage that the core layer is very strong and meets the highest demands in terms of mechanical stability.

According to the invention, the HV battery has a battery protection housing, wherein the EMC shielding is electrically connected to the battery protection housing via a contact. This advantageously integrates the EMC shielding of the underrun protection into another EMC shielding of the battery protection housing, so that the HV battery is completely electromagnetically compatible.

For this purpose, the invention provides that the contact comprises at least one metal socket. An electrical contact is established between the EMC shielding and the battery protection housing via the metal socket. For this purpose, the invention provides that the at least one metal socket is pressed into the underrun protection and is arranged to connect the EMC shielding and the battery protection housing. It is conceivable that a screw, preferably a metal screw, is screwed through the metal socket into the battery protection housing. This creates a secure and electrically conductive, but above all also detachable, connection between the EMC shielding and the battery protection housing. In the event of damage, for example, the underrun protection can be easily replaced without having to structurally interfere with the HV battery.

Alternatively or additionally, according to a further preferred embodiment of the present invention, the contact comprises a metallic band which is arranged to connect the EMC shielding and the battery protection housing. In particular, it can be provided that the battery protection housing is arranged adjacent to the metallic band. It is conceivable that the battery protection housing is screwed to the metallic band. It is preferably provided that the metallic band is incorporated between the lower layer and the upper layer of the underrun protection and that the upper layer is removed in the area of the metallic band. This provides for simple production of the contact via the metallic band.

• 1 illustriert schematisch ein Detail eines Kraftfahrzeugs gemäß einer beispielhaften Ausführungsform der vorliegenden Erfindung mit einem Unterfahrschutz und einer HV-Batterie.
• 2 illustriert schematisch ein Kraftfahrzeug gemäß einer beispielhaften Ausführungsform der vorliegenden Erfindung.

Further details, features and advantages of the invention emerge from the drawings and from the following description of preferred embodiments with reference to the drawings. The drawings merely illustrate exemplary embodiments of the invention, which do not restrict the inventive concept.

• 1 schematically illustrates a detail of a motor vehicle according to an exemplary embodiment of the present invention with an underrun protection and an HV battery.
• 2 schematically illustrates a motor vehicle according to an exemplary embodiment of the present invention.

1 schematically illustrates a detail of a motor vehicle 100 (see 2 ) according to an exemplary embodiment of the present invention with an underrun protection 1 and an HV battery 3, only partially shown. The underrun protection 1 of the motor vehicle 100 serves to prevent damage to the motor vehicle 100, for example when the floor of the motor vehicle 100 touches the ground while driving or due to objects being thrown up which hit the floor of the motor vehicle 100.

The motor vehicle 100 shown here is a hybrid or electric vehicle and has an HV battery 3 as an energy storage device for operating the electric drive machines. The HV battery 3 is arranged as low as possible in the motor vehicle 100, which enables a low center of gravity of the motor vehicle 100. In the embodiment shown here, the HV battery 3 is arranged practically directly above the underrun protection 1 and is only separated from the underrun protection 1 by a gap.

In the event of a thermal event in the HV battery 3, hot, flammable gases can be expelled from the electrodes (not shown) of the HV battery 3. To enable a controlled release of these gases, openings 5 are provided in the base plate 4 of the HV battery 3. The gas from the HV battery 3 can flow through the openings 5 into the space between the HV battery 3 and the underrun protection 1 and be discharged from there. In the embodiment shown here, the base plate 4 comprises a cooling plate for cooling the HV battery 3.

A battery protection housing 9 encloses the AV battery 3 at the sides and at the top (not shown above). The battery protection housing 9 is designed in such a way that it ensures electromagnetic compatibility of the HV battery 3 at the sides and at the top, i.e. it shields the HV battery 3 against incoming and outgoing electrical and electromagnetic fields. This shielding cannot be ensured over the entire surface by the base plate 4, since the openings 5 for degassing the HV battery 3 are provided here.

In order to ensure the electromagnetic compatibility of the HV battery 3 in all spatial directions, the underrun protection 1 has an EMC shield 2. The EMC shield 2 comprises a conductive layer 6 of the underrun protection 1. For this purpose, it is provided, for example, that a conductive film and/or a preferably fine-meshed, conductive grid and/or a metal-vaporized layer is arranged in the underrun protection 1. To protect against mechanical and chemical influences, in particular from outside, it is provided that the underrun protection 1 has an upper layer 7 and a lower layer 8, between which the conductive layer 6 is arranged. The upper layer 7 and the lower layer 8 can each be a fiber composite, for example. It is also conceivable that the upper layer 7 and the lower layer 8 are laminates.

To increase the stability of the underrun protection 1, a core layer 13 is also provided, which is also arranged between the upper layer 7 and the lower layer 8. In the embodiment shown here, the core layer 13 is arranged between the lower layer 8 and the conductive layer 6. However, it is conceivable also that the core layer 13 is arranged between the conductive layer 6 and the upper layer 7. The core layer 13 can be made of PU, for example. In particular, it is provided that the core layer 13 is made of LFI-PUR, which gives the underrun protection 1 a particularly high level of stability.

The EMC shielding 2 is electrically connected to the battery protection housing 9 by means of a contact 10. For this purpose, in the exemplary embodiment shown here, metal bushings 11 are pressed into the underrun protection 1 so that they rest against the conductive layer 6 and the battery protection housing 9. The battery protection housing 9 is also screwed through the metal bushings 11 using metal screws 12 and thus fastened to the underrun protection 1. The metal screws 12 establish a further electrical connection between the conductive layer 6 and the battery protection housing 9. This achieves excellent electrical and electromagnetic shielding and thus good electromagnetic compatibility of the HV battery 3.

Alternatively or additionally, it can be provided that the battery protection housing 9 is arranged adjacent to a metallic band (not shown) and is electrically contacted with the conductive layer 6 via this.

list of reference symbols

1

underrun protection

2

EMC shielding

3

HV battery

4

base plate

5

opening

6

conductive layer

7

upper layer

8

lower layer

9

battery protection housing

10

contacting

11

socket

12

screw

13

core layer

100

motor vehicle

Claims (8)

Motor vehicle (100) having an underrun protection (1), wherein the underrun protection (1) has an EMC shielding (2), wherein the motor vehicle (100) has an HV battery (3), wherein the EMC shielding (2) is arranged below the HV battery (3), wherein the HV battery (3) has a battery protection housing (9), wherein the EMC shielding (2) is electrically contacted with the battery protection housing (9) via a contact (10), characterized in that the contact (10) comprises at least one metallic bushing (11), wherein the at least one metallic bushing (11) is pressed into the underrun protection (1) and is arranged connecting the EMC shielding (2) and the battery protection housing (9). Motor vehicle (100) after claim 1 , characterized in that the HV battery (3) has a base plate (4), wherein the base plate (4) has at least one opening (5) for degassing the HV battery (3), wherein the base plate (4) preferably comprises a cooling plate for cooling the HV battery (3). Motor vehicle (100) according to one of the preceding claims, characterized in that the EMC shielding (2) comprises a conductive layer (6) of the underrun protection (1). Motor vehicle (100) after claim 3 , characterized in that the conductive layer (6) comprises a conductive foil and/or a, preferably fine-meshed, conductive grid and/or a metallically vapor-deposited layer. Motor vehicle (100) according to one of the Claims 3 until 4 , characterized in that the conductive layer (6) is arranged between an upper layer (7) of the underrun protection (1) and a lower layer (8) of the underrun protection, wherein the upper layer (7) and/or the lower layer (8) is preferably a fiber composite and/or wherein the upper layer (7) and/or the lower layer (8) are laminates. Motor vehicle (100) after claim 5 , characterized in that a core layer (13), preferably made of PU or LFI-PUR, is arranged between the lower layer (8) and the conductive layer (6). Motor vehicle (100) according to one of the preceding claims, characterized in that a screw (12) is screwed into the battery protection housing (9) through the metallic bushing (11). Motor vehicle (100) according to one of the preceding claims, characterized in that the contact (10) comprises a metallic band which is arranged connecting the EMC shield (2) and the battery protection housing (9), wherein it is provided in particular that the upper layer (7) in the area of the metallic band is removed.

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