UPPER COVERING PART FORMING A LID FOR BATTERY HOUSING FOR AN ELECTRIC VEHICLE

Abstract

A battery cover for the housing of a battery pack for a battery electric vehicle comprising at least a thermoplastic carrier shaped to form the covering lid characterized in that the outer surface of the covering lid not facing the battery pack is coated on the outer surface of the covering lid with a conductive paint comprising conductive metal or metal-coated particles and whereby the assembly of the thermoplastic carrier and of the coating has an electromagnetic shielding effectiveness of at least 50 dB, preferably at least 60 dB according to ASTM D4935-10.

Claims

1. An upper covering part forming a lid for battery housing for an electric vehicle, comprising: at least a thermoplastic carrier shaped to form the covering lid, wherein the outer surface of the covering lid not facing the battery pack is coated on the outer surface of the covering lid with a conductive paint comprising conductive metal or conductive metal-coated particles; and wherein the assembly of the thermoplastic carrier and of the coating has an electromagnetic shielding effectiveness of at least 50 dB at RF frequencies between 1 kHz and 1.5 GHz according to ASTM D4935-10.

2. The upper covering part forming a lid for battery housing according to claim 1, whereby the conductive metal or metal-coated particles are at least one of silver, silver-plated aluminium, silver-plated copper, silver-plated glass, nickel, zinc, nickel-graphite, copper, steel, aluminium, or combinations thereof.

3. The upper covering part forming a lid for battery housing according to claim 1, whereby the paint is an acrylic based paint or a silicone based coating.

4. The upper covering part forming a lid for battery housing according to claim 1, whereby the conductive coating layer has a thickness of between 20 and 200 m.

5. The upper covering part forming a lid for battery housing according to claim 1, whereby the thermoplastic carrier comprises one of polycarbonate, polyolefin, preferably polypropylene or polyethylene, polyester, preferably polyethylene terephthalate (PET), polyamide or polylactic acid.

6. The upper covering part forming of a lid for battery housing according to claim 1, whereby the material of the thermoplastic carrier is reinforced with fillers, fibers, or textiles to create a composite part.

7. The upper covering part forming a lid for battery housing according to claim 1, further comprising areas covered with an electro-conductive foil.

8. The upper covering part forming a lid for battery housing according to claim 1, further comprising an undercoating between at least the conductive coating and the carrier or a protective coating on at least the conductive coating.

9. The upper covering part forming a lid for battery housing according to claim 1, further comprising means for grounding the conductive layer.

10. A battery box or housing for power cell or cells for a battery electric vehicle, comprising: a lower part and an upper part that fit together to create a hollow space, whereby the upper covering part is forming a lid comprising: at least a thermoplastic carrier shaped to form the lid, wherein the outer surface of the covering lid not facing the power cell or cells is coated on the outer surface of the lid with a conductive paint comprising conductive metal or conductive metal-coated particles; and wherein the assembly of the thermoplastic carrier and of the coating has an electromagnetic shielding effectiveness of at least 50 dB at RF frequencies between 1 kHz and 1.5 GHz according to ASTM D4935-10.

11. The battery box or housing according to claim 10, further comprising a conductive seal between the upper covering part forming the lid and the lower part.

12. A method of making an upper covering part forming a lid for battery housing, according to claim 1, comprising: thermoforming the covering lid; spray coating the outer surface thereof with a conductive paint comprising at least one of silver particles, nickel particles or silver-plated copper particles or a mixture thereof; and drying and or curing the paint, such that the coated surface has an attenuation of at least 50 dB according to ASTM 4935-10.

13. The method according to claim 12, further comprising the step of laminating at least on flatter areas of the outer surface a conductive film or foil such that the conductivity of the film or foil is not impaired during forming of the part.

14. The method according to claim 13, whereby the conductive film or foil is at least partially covered with the conductive paint to obtain a substantially closed conductive layer over the entire outer surface of the cover.

15. The upper covering part forming of a lid for battery housing according to claim 6, wherein the fillers, fibers, or textiles are comprised of natural or synthetic material.

16. The upper covering part forming a lid for battery housing according to claim 7, wherein the electro-conductive foil is an aluminium, a copper, a steel, or a thermoplastic conductive foil.

Description

DESCRIPTION OF EMBODIMENTS

[0036] FIG. 1 schematic drawing of a vehicle

[0037] FIG. 2 schematic drawing of a cover for a battery housing

[0038] FIG. 2A Cross section through the material layers forming the cover.

[0039] FIG. 3 is showing an example for a cover for battery housing.

[0040] FIG. 1 is a schematic drawing of a vehicle comprising at least a battery box or housing 2. The battery box or housing 2 comprises the power cell or cells (not shown) that may be needed for a battery electric vehicle (BEV) or a hybrid electric vehicle (HEV) for instance for electric cars and small people transporting units.

[0041] The battery box or housing 2 comprises an upper covering part forming a lid for battery housing 3 according to the invention and a lower part 4 containing the power cell or cells. Both fit together to form an enclosed space for the power cell or cells. Preferably the box is sealed with a sealing at the area of contact between the upper part and the lower part to prevent dirt and water from entering the box and get in contact with the content in particularly the power cells or the connections between the power cells.

[0042] Preferably the seal is made of an electro conductive silicone comprising electro conductive particles like for instance silver or silver coated particles or nickel or nickel coated particles, for instance nickel coated graphite.

[0043] FIG. 2 is showing the upper covering part forming a lid for battery housing or box in more detail. FIG. 2A is showing a cross section through the material forming the upper covering part. The upper covering part comprises at least a thermoplastic carrier 6 shaped to form the covering lid. The cover is shaped such that it is able to cover at least the open space in the lower part comprising the power cell or cells. Whereby also contours to cover other appliances might be given, for instance to cover additional cooling systems or connections. The battery cover might comprise any ribbing to further increase the stiffness of the cover and or to increase the impact durability.

[0044] The outside surface of the upper part forming the covering lid not facing and or not in direct contact with the power cells is coated with a conductive paint 8 according to the invention, comprising at least metal or metal based particles, for instance one of silver particles or silver-plated copper particles and whereby the coated surface has an attenuation of at least 50 dB, preferably at least 60 dB, at RF frequencies between 1 kHz and 1.5 GHz according to ASTM 4935-10.

[0045] An undercoating 7 may be applied on the thermoplastic carrier before the application of the coating to further enhance resistance of the coating to external influences like water, sand or salt.

[0046] A protective layer 9 may be applied on top of the conductive coating to further enhance the resistance of the surface layer against scratching and chipping. The protective coating may be a coating of polyurethane, either clear or containing colour pigments or dyes.

[0047] Preferably at least the conductive layer has an earth connection to achieve maximum shielding performance. For instance, by using a shielding tape or wire, preferably copper, placed within the coating during the application or the earth connection is first applied and over sprayed with the conductive paint. For a functional earth connection, it is important that the wire or tape is also conductive and in direct contact with the conductive layer.

[0048] FIG. 3 is showing an example of a cover lid for battery housing with a more complex shape, having a channel on top that may accommodate an integrated cooling system or electric appliances in the battery housing or box. Due to the complex shape it might be advantageous to combine the conductive coating according to the invention in areas that are complex shaped and conductive foil or film in areas that are flat shaped. It might also be an option to cover most of the surface with conductive foil or film while a coat is applied over the entire surface to cover any cracks or gaps in the metal foil cover. For instance, in FIG. 3 the flat areas indicated with 11 might be covered with a metal sheet, for instance a copper or aluminium metal foil, preferably with a thickness of between 20 and 100 m, while the other areas including the tunnel 12 can be covered with the conductive coating according to the invention.

[0049] Example of an upper covering part forming a lid for battery housing according to the invention can be a vacuum formed cover, for instance like FIG. 3 made of polycarbonate with at least a conductive coating comprising silver plated copper particles in an acrylic based coating with a density of 0.6 (g/cm.sup.3) and a thickness of 50 m over the outer surface of the part and having a shielding of 60-65 dB at RF frequencies between 1 kHz and 1.5 GHz.

[0050] Upper covering parts forming a lid for battery housing made according to the invention provide not only a good electromagnetic shielding but also an improved resistance to water, salt and dirt coming from the road during driving. Furthermore, in comparison to state of the art covers they have fewer layers and are maintenance free.