Exterior Thermal Battery Cover

Abstract

Exterior thermal battery-cover for a battery housing characterised in that the cover comprises at least a thermal insulating layer with a thermal resistance (R-value) of at least 0.070 m.sup.2.Math.K/W, preferably with a thermal resistance of at least 0.078 m.sup.2.Math.K/W and whereby the thermal insulating layer is at least one of a fibrous layer, an open cell foam layer or closed cell foam layer.

Claims

1. An exterior thermal battery cover for a battery housing, wherein the cover comprises at least a thermal insulating layer with a thermal resistance (R-value) of at least 0.070 m.sup.2.Math.K/W, and wherein the thermal insulating layer is at least one of a fibrous layer, an open cell foam layer, or closed cell foam layer.

2. The exterior thermal battery cover for a battery housing according to claim 1, wherein the porous fibrous layer comprises staple fibers and/or filaments and a binder, and whereby the porous fibrous layer is molded to form a panel with a density of between 150 and 600 kg/m3, a thermal conductivity between 0.03 and 0.06 W/mK, and a thickness of between 2.5 and 10 mm.

3. The exterior thermal battery cover for a battery housing according to claim 1, wherein the fibers and or filaments of the porous fibrous material are based on at least one of organic origin, such as cotton, kenaf, hennep, or thermoplastic material such as polyester preferably PET or PBT, or polyamide, preferably polyamide-6 or polyamide 6,6, or polyolefin preferably polypropylene or polyethylene, or inert material, preferably glass, carbon, kenaf, Nomex or ceramic, or fiber and/or filament mixtures thereof.

4. The exterior thermal battery cover for a battery housing according to claim 1, whereby the fibers and/or filaments have a fiber fineness of between 3 and 10 dtex.

5. The exterior thermal battery cover for a battery housing according to claim 1, whereby the fibers and/or filaments have a hollow or solid cross section.

6. The exterior thermal battery cover for a battery housing according to claim 1, wherein the binder of the porous fibrous material is either a thermoplastic binder or a thermoset binder.

7. The exterior thermal battery cover for a battery housing according to claim 1, further comprising at least one of a micro perforated or airtight wind barrier layer.

8. The exterior thermal battery cover for a battery housing according to claim 7, whereby the wind barrier layer is at least one of a foam, film or foil layer, and/or a membrane type material.

9. The exterior thermal battery cover for a battery housing according to claim 1, whereby the porous fibrous layer is treated with a water repellence agent and/or a water repellent additive is mixed in at least one of the material forming the fibers and/or filaments.

10. The exterior thermal battery cover for a battery housing according to claim 1, whereby the porous fibrous layer is treated with a flame retardant agent and/or a flame retardant additive is mixed in at least one of the material forming the fibers and/or filaments.

11. The exterior thermal battery cover according to claim 1, further comprising a protecting layer formed by a plastic or plastic-fiber composite.

12. The exterior thermal battery cover for a battery housing according to claim 1, further comprising means to mount the exterior thermal battery cover underneath the battery housing on the side facing the road.

13. A battery electric vehicle with at least one battery cell stored in a battery housing having fixations connected to the battery housing, characterised characterized in that an exterior thermal battery cover according to claim 1 is mounted at least underneath the battery housing facing the road.

14. The battery electric vehicle, according to claim 13, wherein the thermal insulating layer includes an enclosed air layer between the battery housing and the thermal insulating layer, and whereby the thermal insulating layer and the enclosed air layer are combined to form a thermal insulating multi-layer with a combined thermal resistance (R-value) of at least 0.070 m.sup.2.Math.K/W, preferably with a combined thermal resistance of at least 0.078 m.sup.2.Math.K/W.

15. A battery-powered electric vehicle according to claim 13, whereby the exterior thermal battery cover is mounted with an enclosed air layer between the surface of the battery housing and the upper surface of the exterior thermal battery cover.

16. The electric vehicle according to claim 13, whereby the battery cover covers at least partially the side of the battery housing and/or adjacent structures and/or body-in-white.

17. The electric vehicle according to claim 13, whereby a sealing is used between the battery cover and at least partially the side of the battery housing and/or adjacent structures and/or body-in-white.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0065] FIG. 1 is a schematic figure of the state of the art situation.

[0066] FIG. 2 is a schematic of a proposed solution.

[0067] FIG. 3 is a schematic of a proposed solution.

[0068] FIG. 4 is a schematic of a proposed solution.

[0069] FIG. 5 is a schematic of a proposed solution.

[0070] FIG. 6 is a schematic of a proposed solution.

[0071] FIG. 1 is showing a vehicle with a body structure (2) and wheels (1). Underneath the body structure a battery housing is mounted facing the road (5). The battery housing (3) might be made of a strong material able to withstand impact like for instance composite or metal, within the housing a frame structure (6) of sorts might be mounted to the internal wall of the battery housing to guarantee a good fixation of the battery cells and or modules within the battery housing. Side beams (4) might be placed alongside the walls of the battery housing and fixed preferably to the body structure to form a stiffened zone that can withstand impact on the car and in particular the battery box during a crash of the car, reducing the risks on the battery modules.

[0072] In the case of the state of the art, the battery modules inside the battery housing is cooled or heated to maintain the temperature within a certain range, however the frame structure (6) structurally connected to the battery housing is forming a temperature bridge to the other side of the battery housing wall. Hence heat (7) is able to radiate from the outside wall to the environment. This is independent from any thermal insulating material placed within the battery housing structure (not shown).

[0073] As the battery housing is directly exposed to the outside environment, in particularly during driving, a flow of air (8) is passing the lower area of the batter box cooling or heating the outside of the battery box even further, thereby reducing the thermal management efforts within the battery housing. In particular, increase the energy used for maintaining a constant temperature of the battery elements and or modules.

[0074] FIGS. 2 to 6 show different design situations how to combine the exterior battery cover as disclosed so far with a battery housing on a vehicle. All material or material combinations disclosed before and following can be freely combined according to the beneficial features they provide.

[0075] FIGS. 2 and 3 are showing the same constellation as shown in the state of the art, however the battery housing is covered with an exterior thermal battery cover (9) according to the invention. The battery cover can be made of a fibrous or foam material. Or can be made by a combination of a plastic shell and a thermal insulating inlay made of foam or felt between the shell and the outer surface of the battery housing.

[0076] In a first embodiment (FIG. 2) the exterior thermal battery cover is placed adjacent the battery housing. The exterior cover may be glued over the full surface or only around the rim, leaving a minimal enclosed air layer between the surfaces. Even a minimal enclosed air layer is already sufficient to decouple the surface of the battery housing thermalyl radiating and the exterior cover.

[0077] In a second embodiment (FIG. 3) the exterior cover is placed with a dedicated enclosed air layer (12). A dedicated enclosed air layer may be achieved by the means for mounting (10), including spacer parts into the mounting and or by the moulded shape design with for instance at least one recess to create such a dedicated enclosed air layer. To prevent a stream of air from entering via the enclosed air layer between the lower surface of the battery housing and the adjacent surface of the exterior cover, a sealing (11) at least around at least a part of the rim might be beneficial to close the enclosed air layer, preferably keeping the area enclosed as large as possible. The spacer function and the sealing might be integrated in the same material solution.

[0078] Alternatively, the exterior cover (9) may be extended to include surrounding structures alongside the battery housing like for instance the stiffening beams (FIG. 4). Preferably the exterior cover is made of a porous fibrous material according to the invention, compressed to withstand the impact of stones known as stone chipping. The material can be thermally moulded to form a fitting shape to cover the battery housing structure and possible adjacent structures.

[0079] The design of the cover can also help to smooth out battery housing structures like beams, to obtain a more aerodynamic surface underneath the cover or an optimised drag performance. Optionally a dedicated enclosed air layer (12) in the form of a recess or recesses might be integrated in the moulded shape. Although it is not necessary for the thermal function a high bending stiffness is preferential for keeping the part in its shape during use as well as increasing the durability against stone chipping. Surprisingly, the high density fibrous material gives still a very good performance keeping the battery temperature more constant. It could be shown that by using such a panel structure either with or without enclosed air layer was able to reduce the amount of energy by

[0080] An extension of the exterior battery cover along and over a corner of the part to cover also the side of the battery housing and/or the adjacent structures to further encapsulate the lower areas and prevent winds from blowing pass possible heat sinking structures might further reduce the heat sink effects.

[0081] In FIGS. 5 and 6 the different material solutions are depicted against the same battery housing situation as depicted in FIG. 1-3.

[0082] The engine cover shield (9) comprises at least one thermal insulating layer (14) of a porous fibrous material. It might further comprise a second layer that is able to stop wind and/or water (13). This layer can be either one of a film, foil, impervious foam layer or microporous membrane layer. The film or foil layer might be a monolayer film or a bilayer film. Although it has to be watertight or wind tight, it might still be a breathable film or foil able to let condense water formed in the area between battery housing and cover escape. The membrane can have a similar behaviour and can be one that is the same or similar to the membranes sold under the trademark of Goretex. By preventing wind from pressing into the porous fibrous material the steady air in the undercover material and eventually in the enclosed air layer is not disturbed. This further increases the thermal insulation under in particularly driving condition at higher speeds. This wind proof and or water proof layer can be placed either facing the battery housing or facing the road. Optionally a film can be placed on both sides of the porous fibrous layer. Eventually the porous fibrous layer may be enwrapped and sealed within such a layer, forming a wind and or water proof pouch.

[0083] In a further preferred solution a wind and or water proof layer (16) is placed between 2 fibrous layer to form a sandwich construction. The first fibrous layer (14) might be the same or different from the second fibrous layer (15). The fibrous layer might be different in fiber composition, mixture and or fineness and or the amount of binder used. For example, the outer fibrous layer (14) might have a higher binder content than the inner fibrous layer to get a better stone chipping performance and a difference in thermal conductivity between the layer close to and/or adjacent the battery housing and the one facing the road. In addition, further treatment of the inner fibrous layer (15) and the outer fibrous layer (14) might be different, for instance it might be beneficial to treat only one side with a flammability and or a water-repellent treatment. For instance, both layers are from the same or similar basic fibrous material, but the outer layer obtains the water repellent treatment and the inner layer the flame retarding treatment.

[0084] This can be also beneficial for the environment as the outer fibrous layer might be more in contact with rainwater and might leach its treatment into the rainwater. While the inner fibrous layer is mostly protected by the wind and/or water proofing layer and the treatment might not be exposed to high levels of water.