Intumescent battery enclosure

Abstract

A fire-proofed enclosure for housing one or more battery units is provided. The enclosure comprises a housing formed entirely or essentially from a cloth-based material coated or impregnated with a solution which contains an intumescent material. An internal scaffold prevents distortion of the enclosure during use and under thermal stress. The enclosure further includes at least one wall configured to form an aperture through which power delivery cabling can pass. This aperture is configured to close upon exposure to excessive heat through expansion of the intumescent material. In preferred embodiments, the enclosure incorporates internal and / or external layers of impact-absorbing intumescent material to protect against mechanical abuse, as well as a thermoplastic tube containing an extinguishing agent that activates in the event of a fire. The enclosure is configured to smother and isolate batteries experiencing thermal runaway, thereby mitigating fire risk in electric vehicles or during battery charging.

Description

INTUMESCENT BATTERY ENCLOSUREFIELD OF THE INVENTION

[0001] The present invention relates to a fire-proofed enclosure for a battery unit of a battery powered vehicle.BACKGROUND TO THE INVENTION

[0002] In recent years, personal urban transportation, particularly in cities, is increasingly mediated by electric battery powered vehicles, such as, but not limited to, electric cars, electric vans, electric scooters (e-scooters), electric bikes (e-bikes), electric motorcycles, electric trikes, electric hoverboards, electric skateboards and electric unicycles.

[0003] Furthermore, petrol and diesel powered vehicles used in the emergency service and public transportation industry are also being increasingly replaced by electric battery powered vehicles.

[0004] In part, the increase in the aforementioned modes of transport is the result of improved battery technology. Historically, lead-acid batteries were exploited for their low cost and simplicity, wherein electricity was produced by a chemical reaction between lead, lead dioxide and sulphuric acid.

[0005] Similarly, nickel-cadmium (NiCd) batteries were historically popular; in particular NiCd batteries provided a consistent output over a broad range of temperatures and demonstrated a tolerance to a high volume of charge-discharge cycles.

[0006] However, lead-acid batteries are heavy, large items and comprise a low energy density with respect to available alternatives. Furthermore, NiCd batteries are subject to ‘memory effect’ wherein, if the battery is recharged prior to fully discharging all stored energy, the battery will ‘remember’ a smaller capacity and therefore impart a decreased energy storage capacity overtime with respect to each charge-discharge cycle. Moreover, the composition of both lead-acid and NiCd batteries negatively affects the environment via their heavy metal constituents, lead and cadmium.

[0007] More recently, lithium-ion technology has provided high energy density batteries, allowing for lightweight, compact energy storage solutions suitable for use in electric battery powered vehicles. Electric battery powered vehicles, such as an e-scooter, benefit from an increased range, when using LiBs when compared with lead-acid and NiCd batteries. Furthermore, unlike NiCd batteries, LiBs are not subject to the ‘memory effect’.

[0008] Even when considering the relatively high cost of LiBs, with respect to lead-acid and NiCd batteries, the benefits of high energy density, reachability, low-cost, increased life span and compact size have led to a major adoption of LiBs in the electric battery powered vehicle market.

[0009] Despite the aforementioned advantages, LiBs and other types of electric batteries used in electrically powered vehicles, present a substantial fire risk. Concurrent with major adoption of LiBs and the large growth in the personal electric battery powered transport market, the London Fire Brigade (LFB) attended over 116 fires involving e-scooters and e-bikes in 2022. By Autumn of 2023, at least 3 deaths and 51 injuries had been attributed to electric vehicle associated Li B fires in London alone.

[0010] Thermal runaway and fire of LiBs is well understood and mainly caused by electrical abuse (over- charging / discharging), thermal abuse (over-heating), mechanical abuse (penetration, pinching or bending) and internal short circuits (ISC).

[0011] Electric vehicles used in emergency service applications, such as police vehicles, are subject to operational demands and hazards not typically encountered by standard consumer vehicles. Police vehicles are frequently involved in high-risk manoeuvres, including pursuits, tactical stops, and deliberate ramming. Such ramming incidents pose a significant threat to the structural integrity of the vehicle, including the battery compartment. Mechanical impact and deformation resulting from these manoeuvres can lead to direct physical damage to the electric batteries including LiBs housed within the vehicle chassis. This mechanical abuse significantly increases the risk of thermal runaway, fire, and explosion, particularly in the event of penetration or crushing of battery cells. Accordingly, the use of electric vehicles in the police service has been limited, in part, by the lack of suitable protective systems capable of mitigating the consequences of mechanical abuse to the battery compartment during routine enforcement activities.

[0012] Smaller electric vehicles such as e-scooters and e-bikes have removable LiBs for ease of charging. However, it is appreciated that the removal of LiBs from their in-situ location to a charging location increases the LiBs exposure to mechanical abuse. Furthermore, often LiBs are charged unattended by the user, increasing the LiB’s exposure to electrical abuse. Users may also charge LiBs upon an inappropriate surface or location, such as a space which insulates the LiB and therefore increases the risk of thermal abuse. Consequently, most domestic LiB fires occur when the battery is charging, rather than in use.

[0013] GB2532933 teaches a temporary enclosure for housing battery powered mobility vehicles, such as mobility scooters, during charging. The temporary enclosure being self-standing and comprises a cover of fire-proofed cloth material supported on a frame. The closure includes a closable opening to permit entry and exit of a mobility vehicle to and from the enclosure interior and means for connecting the power source of the vehicle to the mains. The cloth material may comprise a silicone coated glass cloth having at least 1200 degrees Celsius (°C) fire protection, a polyurethan material having at least 1100°C fire protection, or a graphite cloth material having at least 1200°C fire protection. The frame may comprise an assembly of metallic or plastic rods and clips. In addition to being fire-proofed, the cloth material may be water resistant.

[0014] GB2532933 effectively impedes the outbreak and spread of fire from a charging Li B housed within a mobility vehicle. However, due to a lack of a base, impact-absorbing material, internal scaffold, ventilation and the size of the temporary enclosure, the apparatus taught in GB2532933 would not be appropriate for housing individually charging LiBs or for use in electric vehicles.

[0015] US 2024 / 0190109 teaches a structure comprising several layers, the layers comprising: one or more nonwoven layers; wherein each of the nonwoven layers has a temperature resistance of around 200°C or greater; and wherein the article is adapted to provide thermal insulation for a battery and avoid and / or contain fire propagation during a battery thermal runaway event. However, the disclosed apparatus lacks an internal scaffold or supporting framework. As a result, it does not possess sufficient structural integrity to maintain its shape under stress or during operation. Consequently, the apparatus taught in US 2024 / 0190109 would be unsuitable to use as a battery enclosure in electric vehicles, where resistance to deformation and mechanical robustness are critical requirements.

[0016] The present invention sets out to provide an enclosure for housing electric vehicle batteries, including LiBs, which is specifically configured to protect the enclosed battery or batteries from mechanical damage resulting from vehicular collisions, such as those commonly encountered during emergency vehicle operations, and to isolate and protect users and surroundings from hazards associated with electric vehicle batteries undergoing thermal runaway and fire, particularly during charging.STATEMENT OF THE INVENTION

[0017] In a first aspect, the invention provides a fire-proofed enclosure to house one or more batteries, said enclosure comprising a housing produced entirely, or essentially from a material coated or impregnated with a solution which contains an intumescent material; and an internal scaffold configured to prevent distortion of the enclosure during use thereof.

[0018] In a second aspect, the invention provides a fire-proofed enclosure to house batteries when charging, said enclosure comprising a housing produced entirely, or essentially from a material coated or impregnated with a solution which contains an intumescent material; an internal scaffold which prevents distortion of the enclosure during use thereof; and; formed with discrete openings through which power delivery cabling can pass, the housing further including at least one ventilation opening which is closed in the event of excessive heat through rapid expansion of the intumescent material.

[0019] In a third aspect, the invention provides a fire-proofed enclosure to house batteries, said enclosure comprising a housing produced entirely, or essentially from a material coated or impregnated with a solution which contains an intumescent material; an internal scaffold which prevents distortion of the enclosure during use thereof; an internal layer of impact-absorbing intumescent material; and; at least one wall configured to form an aperture through which power delivery cabling can pass.

[0020] Preferably, the enclosure comprises front, rear and side walls covered by a lid connected to one wall through a hinge.

[0021] Preferably, the enclosure includes one or more pierceable patches or gaskets on at least one of the walls and / or lid configured to form a sealing fit around a power cable passed therethrough and close upon intumescent expansion in the event of a fire.

[0022] Preferably, the lid includes downwardly extending side walls and a downwardly extending front wall which extend over the upper sections of the front and side walls of the enclosure.

[0023] Preferably, the internal scaffold is comprised of support members substantially located on the upper internal margin of the enclosure front and side walls.

[0024] Preferably, the support members comprise elongate strips formed of stainless steel.

[0025] Preferably, hook-and-loop fasteners, for example Velcro™ tapes, are substantially located on the upper external margin of the enclosure front and side walls and the reciprocal faces of the downwardly extending front and side walls of the lid.

[0026] Preferably, one or more securement means are located on the upper margin of the enclosure front and / or side walls.

[0027] Preferably, the enclosure includes a base on which the respective battery unit locates.

[0028] Preferably, the enclosure includes at least one layer of impact absorbing compressive material coated with a material which intumesces in the presence of excessive heat on the interior surface or surfaces of the enclosure.

[0029] Preferably, the enclosure includes at least one layer of impact absorbing compressive material coated with a material which intumesces in the presence of excessive heat on the exterior surface or surfaces of the enclosure.

[0030] Preferably, the enclosure includes a sealed thermoplastic tube which contains an extinguishing gas or fluid which is released from the tube in the event of a fire occurring within the enclosure.

[0031] Preferably, the base includes a layer of a fire-retardant lining.

[0032] Preferably, the fire-retardant lining comprises of two layers of a cloth material coated with a material which intumesces when exposed to excess heat either side of a sheet of paper card material.

[0033] Preferably, the enclosure includes at least one ventilation opening which is closed in the event of excessive heat or fire through rapid expansion of the intumescent material.BRIEF DESCRIPTION OF DRAWINGS

[0034] The invention will now be described by way of example with reference to the accompanying diagrammatic drawings in which:

[0035] Figure 1 is a front view of a fire-proofed enclosure in accordance with one embodiment of the present invention;

[0036] Figure 2 is a rear view of the fire-proofed enclosure as illustrated in Figure 1 ;

[0037] Figure 3 is a side view of the fire-proofed enclosure as illustrated in Figures 1 and 2;

[0038] Figure 4 is a perspective view of the fire-proofed enclosure illustrated in the preceding Figures, wherein the lid is in the open position;

[0039] Figure 5 is a first perspective view of a fire-proofed enclosure in accordance with a second embodiment of the present invention;

[0040] Figure 6 is a rear perspective view of the fire-proofed enclosure as illustrated in Figure 5;

[0041] Figure 7 is a side perspective view of the fire-proofed enclosure as illustrated in Figures 5 and 6, wherein the lid is partially open;

[0042] Figure 8 is a top plan perspective view of the fire-proofed enclosure as illustrated in Figures 5 to 7, wherein the lid is in the open position and the interior surface of the enclosure is shown;

[0043] Figure 9 is a second perspective view of the fire-proofed enclosure as illustrated in Figures 5 to 8, demonstrating the interior surface of the lid; and

[0044] Figure 10 is a perspective view of a fire-proofed enclosure in accordance with a third embodiment of the present invention.DETAILED DESCRIPTION OF THE INVENTION

[0045] The fire-proofed battery enclosure 10 illustrated in Figures 1 to 10 of the drawings is typically produced from a cloth or fabric or card material (hereinafter referred to simply as a “cloth” material) coated or impregnated on one or both sides with a solution which includes an intumescent material to produce a relatively rigid structure. The cloth material may be adhered to a rigid or semi-rigid backing sheet of, for example, a paper card or paper card-like material.

[0046] The enclosure 10 is typically produced by stitching or otherwise joining together suitably dimensioned pieces of intumescent coated cloth material to form a rigid or semi-rigid enclosure body.

[0047] The enclosure 10 may comprise a front wall 12, opposing side walls 14, a rear wall 16, a base 15 and a closable lid 18 formed with downwardly extending side walls 20 and a downwardly extending front wall 22. As mentioned previously, the cloth material forming these walls is coated or impregnated on one or both sides with a solution containing an intumescent material and may optionally be bonded to a rigid or semi-rigid backing sheet, such as a paper card or paper card-like substrate, to enhance structural integrity. In the event of a fire occurring within the enclosure 10, the enclosure 10 will smother the battery contents of the enclosure 10 to rapidly or immediately smother and extinguish said fire.

[0048] As shown in Figure 3, the lid 18 is connected to the rear wall 16 via a fold 24 in the material of the enclosure 10, the fold 24 acting as a hinge. In an alternative arrangement, the lid 18 may be stitched to the upper surface of the rear wall 16 which defines a hinge to assist opening and closing of the enclosure 10. Furthermore, the lid 18 may be separable from the side walls 14 and front walls 12 of the enclosure 10.

[0049] Preferably, the lid 18 is connected to the rear wall 16, however, the lid 18 may be connected to any one of the walls of the enclosure 10.

[0050] The downwardly extending side walls 20 of the lid 18 extend over and overlap the upper portions of the front walls 12 and side walls 14 of the enclosure 10 when the lid 18 is closed to provide enhanced protection.

[0051] Once constructed, the assembled enclosure 10, includingthe stitching, is coated with an additional coating of a material which intumesces in the presence of excess heat. Once coated, the enclosure 10 is relatively free standing.

[0052] Fastening means 26 (as shown in Figures 3, 4, 7, 9 and 10) such as high-temperature hook-and-loop fasteners (for example, Velcro™), fire-retardant snap-fit buttons, magnetic closures, toggle latches, turn buttons, swivel latches or interlocking tabs may be secured to the external surfaces of the side walls 14 and / or front wall 12, and to the internal surfaces of the downwardly extending front 22 and side walls 20 of the lid 18 to enable the enclosure 10 to be closed once a battery unit has been positioned within therespective enclosure 10. The selected fastening means 26 may be chosen based on the required strength, ease of operation, thermal resistance, and serviceability.

[0053] To ensure sufficientfastening integrity between the external surfaces of the side walls 14 and / or front wall 12, and the internal surface of the downwardly extending front 22 and side walls 20 of the lid 18 and enclosure 10 body, respectively, a support member 38 is fastened about the internal surfaces 42, 40, and 44 of the enclosure 10 to provide reinforcement beneath the respective fastening regions (as shown in Figures 4, 7 and 8).

[0054] Specifically, the support member 38 is located at least substantially in a reciprocal region corresponding to the location of the fastening means 26, such that the front wall 12 and side walls 14 of the enclosure 10 are structurally supported, thereby reducing distortion and ensuring that the lid 18 and downwardly extending front wall 22 and side walls 20 maintain secure and repeatable engagement with the body of the enclosure 10.

[0055] Alternatively, the support member 38 may extend to support the entire frame of the enclosure 10, whereby the support member 38 acts as an internal scaffold. Alternatively, the support member 38 may, as illustrated, comprise elongate strips which traverse at least the three internal surfaces 42, 40 and 44 of the enclosure 10 (Figures 4 and 8).

[0056] The elongate strips may also be arranged to form a scaffold; by way of example, but not limited to, said strips may be assembled as cross braces, corner posts or strapping beams.

[0057] The support member 38 may be in the form of panels, which may be arranged as partition inserts or act as double-walling means to support the enclosure 10.

[0058] The support member 38 may be formed of any suitable non-flammable or flame-retardant material such as, but not limited to, stainless steel, mineral fibres, ceramic fibres, asbestos-free calcium silicate boards, basalt fibre and phenolic foam.

[0059] The support member 38 may be fastened to the internal surfaces 42, 40 and 44 of the enclosure 10 by any suitable non-flammable or flame-retardant fastening means such as, but not limited to, stainless steel fasteners, ceramic fasteners, glass-filed nylon fasteners, PTFE (polytetrafluorethylene) coated fasteners, silicone rubber fasteners, and / or brass fasteners.

[0060] Alternatively, the support member 38 may be fastened to the internal surfaces 42, 40 and 44 of the enclosure 10 by any suitable high-temperature resistant adhesives such as, but not limited to, epoxy adhesives, silicone adhesives, ceramic adhesive and polyimide adhesives, or adhesives containing a material which intumesces in the presence of excess heat.

[0061] The support member 38 ensures that the structure of the enclosure 10 does not collapse onto an enclosed battery unit and encourage thermal runaway. In addition, the support member 38 ensuressufficient sealing of the enclosure 10 when in use, such that in the event of thermal runaway, the enclosure 10 maintains its structure during intumescent expansion therefore facilitating the sealing of the spaces between the lid 18 and the enclosure 10 body, causing smothering of the fire.

[0062] In one embodiment of the invention, one or more internal surfaces of the walls 40, 42, 44, 46, base 15, and / or lid 18 of the enclosure 10 may be lined with discrete or layered impact-absorbing intumescent material 64, to provide enhanced resistance to mechanical and thermal abuse (Figures 5 to 10).

[0063] Discrete or layered impact-absorbing intumescent material 62 may be fitted to one or more external surfaces of the walls 12, 14, 16, and / or lid 18 of the enclosure 10.

[0064] The impact-absorbing intumescent materials 62, 64 may be secured to one or more internal surfaces of the walls 40, 42, 44, 46, external surfaces of the walls 12, 14, 16, base 15 and / or lid 18 of the enclosure 10 using any suitable fastening means, including but not limited to, high-temperature adhesive bonding; hook-and-loop fasteners (for example, Velcro™) for removable configurations; mechanical fasteners such as rivets or screws; lamination to the enclosure internal walls 12, 14, 16; thermal welding for compatible thermoplastic materials; or stitched integration using high-temperature threads. Alternatively, the enclosure 10 may comprise recessed pockets or sleeves configured to retain the impact-absorbing materials 62, 64 in position without permanent fixation.

[0065] In a preferred embodiment, one or more impact-absorbing intumescent materials 62, 64 are positioned on the internal wall surfaces 40, 42, 44, 46, external wall surfaces 12, 14, 16, base 15, and / or lid 18 of the enclosure 10. Placement of such impact-absorbing intumescent materials 62 may be selected based on the desired balance between mechanical energy absorption, thermal shielding, and retention of the battery in situ during impact events.

[0066] When located on the internal wall surfaces 40, 42, 44, 46, base 15, and / or internal surface of the lid 18 of the enclosure 10, high-friction, compliant intumescent materials, such as intumescent rubber compounds or textured polyurethane foams, may serve to secure the battery pack in position under dynamic loads, while also providing cushioning to reduce the transmission of mechanical shock. These materials may also inhibit battery movement during ramming, crash events or high-speed manoeuvres.

[0067] When located on the external wall surfaces 12, 14, 16 and / or external surface of the lid 18 of the enclosure 10, more rigid or structural intumescent materials, such as graphite-based sheets or epoxy composites, may serve as a defence against penetrative impact and thermal insult, absorbing energy and forming a protective char layer under elevated temperature conditions.

[0068] In some configurations, complementary combinations of internal and external impact-absorbing intumescent materials 62, 64 are employed to create a synergistic effect, whereby impact energy is distributed across multiple interfaces and through materials of equal or differing properties. Byway of example, but not limited to, a rigid external impact-absorbent intumescent material, such as anintumescent foam, may initially absorb kinetic energy, while a viscoelastic internal impact-absorbent intumescent material, such as an intumescent rubber, dissipates residual forces and stabilises the battery position.

[0069] By positioning impact-absorbing intumescent materials 62, 64, on the internal wall surfaces 40, 42, 44, 46, external wall surfaces 12, 14, 16, base 15, and / or lid 18, respectively, the enclosure 10 provides enhanced protection against both mechanical abuse and thermal runaway.

[0070] This arrangement is particularly advantageous in emergency service vehicles, such as police vehicles, where vehicular collision or deliberate ramming may impose sudden and severe mechanical loads on the battery enclosure.

[0071] In one embodiment of the invention, the rear wall 16 of the enclosure 10 includes a gasket 34 which includes several ventilation openings 36 to assist cooling of the enclosure interior (Figures 2 and 4). These ventilation openings 36 may also be used to pass a power cable therethrough. The gasket 34 includes a coating which includes a material which intumesces in the event of a fire. In the event of a fire occurring within the enclosure 10, the intumescent coating rapidly expands to close the ventilation openings 36 to inhibit the spread of fire to the surrounding area. Similar gaskets 34 may be located on the front 12 and / or side walls 14 of the enclosure 10, or on the lid 18.

[0072] Furthermore, as seen from Figure 3, the downwardly extending front wall 22 of the enclosure 10 may be left at least partially detached from the downwardly extending side walls 20 along at least one of its sides to define an opening for the entry of power cabling or other connecting means 22a. Similarly, the upper end of the sides of the front wall 12 of the enclosure 10 may be left partially open to receive such cabling.

[0073] In an alternative embodiment of the invention, the rear wall 16 of the enclosure 10 includes a pierceable patch 54 (Figure 6). The patch 54 is configured such that the material is easily puncturable, such that a cable can be passed therethrough. The patch 54 is configured, such that when a cable is passed through, it conforms closely around the cable to form a close-fitting sealing engagement.

[0074] The patch 54 includes a coating which includes a material which intumesces in the event of a fire. In the event of a fire occurring within the enclosure 10, the intumescent coating rapidly expands to close the punctured openings to inhibit the spread of fire to the surrounding area. Similar patches 54 may be located on the front 12 and / or side walls 14 of the enclosure 10, or on the lid 18.

[0075] In an alternative embodiment of the invention, the enclosure 10 may be constructed without ventilation openings or provisions for power cabling to pass from the exterior of the enclosure 10 to the interior. This configuration may be advantageous, for example, when using an auxiliary battery pack to charge a portable electronic device, such as a mobile phone. In this scenario, the electronic device, battery, and connection components are all fully enclosed within the enclosure 10.

[0076] The cloth pieces from which the enclosure 10 is constructed and the impact-absorbing intumescent material 62, 64 are coated on one or both sides with a solution which contains a sufficient quantity of intumescent material to cause, in the event of a fire occurring within the enclosure 10, the enclosure 10 to enclose and smother the battery contents of the enclosure to rapidly or immediately smother and extinguish said fire.

[0077] In a preferred arrangement a sealed thermoplastic tube filled with an extinguishing gas is positioned within each fire-proofed enclosure 10, the sealed tube operatingto release liquid, gas orfluid in the event of a fire occurring within the enclosure 10 to extinguish said fire within seconds.

Claims

CLAIMS1 . A fire-proofed enclosure for housing one or more battery units, said enclosure comprising: a housing produced entirely or essentially from a material coated or impregnated with a solution which contains an intumescent material; and; an internal scaffold configured to prevent distortion of the enclosure during use thereof.

2. An enclosure according to claim 1 , wherein the enclosure comprises a front wall, rear wall and side walls covered by a lid hingedly connected to one wall.

3. An enclosure according to claim 2, wherein at least one wall and / or the lid includes a pierceable patch or gasket configured to form a sealing fit around a power cable passed therethrough and close upon intumescent expansion in the event of a fire.

4. An enclosure according to claim 2, wherein the lid includes downwardly extending side walls and a downwardly extending front wall configured to overlap the upper portion of the front and side walls of the enclosure when closed.

5. An enclosure according to any preceding claim, wherein the internal scaffold is comprised of one or more support members substantially located along an upper internal margin of the enclosure front and side walls.

6. An enclosure according to claim 5, wherein the support members comprise elongate strips formed of stainless steel.

7. An enclosure according to any preceding claim, wherein at least one fastening means is substantially located on the upper external margin of the enclosure front and side walls and the reciprocal faces of the downwardly extending side walls and front wall of the lid.

8. An enclosure according to claim 7, wherein the fastening means is a hook-and-loop fastener tape.

9. An enclosure according to claims 7 and 8, wherein one or more additional fastening means, such as a turn button / buttons, are located on the upper margin of the enclosure front and / or side walls.

10. An enclosure according to any preceding claim, wherein the enclosure includes a base on which the respective battery locates.11 . An enclosure according to any preceding claim, wherein the enclosure includes at least one internal layer of impact-absorbing compressive material, coated with an intumescent material, lining one or more internal wall surfaces, the base, and / or the internal surface of the lid.

12. An enclosure according to any preceding claim, wherein the enclosure includes at least one external layer of impact-absorbing compressive material, coated with an intumescent material, lining one or more external wall surfaces, and / or the external surface of the lid .

13. An enclosure according to any preceding claim, wherein the enclosure includes a sealing thermoplastic tube which contains an extinguishing gas or fluid which is released from the tube in the event of a fire.

14. An enclosure according to any preceding claim, wherein the enclosure walls, base and / or lid includes a multi-layer fire-retardant lining comprising two layers of a cloth material coated with a material which intumesces when exposed to excess heat either side of a layer of paper card material.

15. An enclosure according to any preceding claim, wherein the enclosure further includes at least one ventilation opening which is closed in the event of excessive heat through rapid expansion of the intumescent material.

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