Intumescent battery charging enclosure

Abstract

A fire-proofed enclosure (Fig. 1, 10) to house batteries when charging, comprising a housing made from a material coated or impregnated with an intumescent material and an internal scaffold, and inclu

Description

FIELD OF THE INVENTION This invention relates to a fire-proofed enclosure for a battery unit of a battery powered vehicle. BACKGROUND OF THE INVENTION In recent years personal urban transportation, particularly in cities, is increasingly mediated by electric battery powered vehicles, such as, but not limited to, electric scooters (e-scooters), electric bikes (e-bikes), electric motorcycles, electric trikes, electric hoverboards, electric skateboards and electric unicycles. 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. 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. 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 affect the environment via their heavy metal constituents, lead and cadmium. More recently, lithium-ion technology has provided high energy density batteries, allowing for lightweight, compact energy storage solutions suitable for use in a personal electric battery powered vehicle. Electric battery powered vehicles, such as an e-scooter, benefit from an increased range, when using lithium-ion batteries (LiBs) when compared with lead-acid and NiCd batteries. Furthermore, unlike NiCd batteries, LiBs are not subject to the ‘memory effect’. Even when considering of 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, in particular with respect to e-scooters and e-bikes. Despite the aforementioned advantages, LiBs 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 LiB fires in London alone. 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). It is appreciated that the removal of LiBs from their in situ location to a charging location increases the LiB’s 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 LiB’s to thermal abuse. Consequently, most domestic LiB fires occur when the battery is charging, rather than in use. 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 fire protection, a polyurethan material having at least 1100 degrees Celsius fire protection, or a graphite cloth material having at least 1200 degrees Celsius 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. GB2532933 effectively impedes the outbreak and spread of fire from a charging LiB housed within a mobility vehicle. However, due to a lack of base, ventilation and the size of the temporary enclosure, the apparatus taught in GB2532933 would not be appropriate for housing an individually charging LiB. The present invention sets out to provide an enclosure to house LiBs when charging and to isolate and protect users from LiBs undergoing thermal runaway and fire. SUMMARY OF THE INVENTION In one 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. Preferably, the housing comprises front, rear and side walls covered by a lid connected to the rear wall through a hinge. Preferably, the internal scaffold is comprised of support members substantially located on the upper internal margin of the housing front and side walls. In the preferred embodiment, the support members comprise elongate strips formed of stainless steel. Preferably, the lid includes side pieces which extend downwardly from the upper margins of the front and side walls of the housing. Preferably, Velcro (RTM) tapes are substantially located on the upper external margin of the housing front and side walls and the reciprocal faces of the lid side pieces. Preferably, the housing 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 housing. An enclosure as claimed in any one of the preceding claims, wherein housing includes a base on which on the respective battery unit locates. BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described by way of example only with reference to the accompanying diagrammatic drawings in which: Figures 1 and 2 are respectively front and rear elevation views of a battery charging enclosure in accordance with the invention; Figure 3 is a side view of the enclosure illustrated in Figures 1 and 2; and Figure 4 is a perspective view of the enclosure illustrated in the preceding figures, wherein the lid is open. DETAILED DESCRIPTION OF THE INVENTION The battery charging enclosure 10 illustrated in Figures 1 to 4 of the drawings is typically produced from a cloth or fabric or card material (hereinafter referred to simply as a “cloth” material) coated 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 card or card-like material. The housing is typically produced by simply stitching suitably dimensioned coated cloth pieces together to form a suitably shaped and dimensioned body which comprises a front wall 12, side walls 14, a rear wall 16 and a closable lid 18 formed with downwardly extending side walls 20 and a downwardly extending front wall 22. The rear wall 16 of the housing includes a patch 34 which includes several ventilation openings 36 to assist cooling of the housing interior. The patch 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 housing, the intumescent coating rapidly expands to close the openings to inhibit the spread of fire to the surrounding area. Similar patches may be located in the front and / or side walls of the housing. As shown in Figure 3, the lid is connected to the rear wall via a fold 24 in the material of the housing, the fold 24 acting as a hinge. Once completed, the assembled housing including the stitching is coated with an additional coating of an intumescent material. The downwardly extending side walls 20 of the lid 18 extend over the upper sections of the front and side walls of the housing when the lid is closed to provide enhanced protection. Once coated, the housing is relatively free standing. Velcro (RTM) tapes 26 are secured to the external surfaces of the side walls 14 and to the internal surfaces of the overlapping sides 20,22 of the lid 18 to enable each housing to be closed once a battery unit has been positioned within the respective housing. To ensure sufficient fastening of the Velcro (RTM) tapes 26 to the external surfaces of the side walls 14 and internal surface of the overlapping sides 20,22 of the lid 18, a support member 38 is fastened about the inner surfaces 42, 40 and 44 of the enclosure 10. Specifically, the support member 38 is at least located substantially in a reciprocal region concordant to the location of the Velcro (RTM) tapes 26, such that the front 12 and side walls 14 are prevented from distorting and retain a structure concordant to the lid 18 and overlapping sides 20 and 22. Alternatively, the support member 38 may extend to support the entire frame of the fire protected 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 inner surfaces 42, 40 and 44 of the enclosure 10. 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, comer posts or strapping beams. 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. 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. The support member 38 may be fastened to the inner surfaces 42, 40 and 44 of the enclosure 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, brass fasteners. Alternatively, the support member 38 may be fastened to the inner surfaces 42, 40 and 44 by any suitable high-temperature resistant adhesives such as, but not limited to, epoxy adhesives, silicone adhesives, ceramic adhesive and polyimide adhesives. The support member 38 ensures that the structure of the enclosure 10 does not fold onto an enclosed charging battery unit and encourage thermal runaway. In addition, the support member 38 ensures sufficient sealing of the enclosure when in use, such that in the event of thermal runaway, the enclosure maintains its structure during intumescent expansion therefore facilitating the sealing of the spaces between the lid 18 and the enclosure body and the smothering of the fire. As will be seen from Figure 3, the material between the lid 18 and the rear wall 16 defines a hinge to assist opening and closing of the housing. As will also be seen from Figure 3, the front wall 22 of the housing is left at least partially open along at least one of its sides to define an opening for the entry of cabling or other connecting means from adjoining charging means. Similarly, the upper end of the front wall 12 of the housing may be left partially open to receive such cabling. In an alternative arrangement, the lid 18 is separable from the side and front walls of the housing. As mentioned above, the cloth pieces from which the cover is constructed 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 housing, the housing to collapse onto and smother the battery contents of the housing to rapidly or immediately smother and extinguish said fire. Located in the rear wall 16 of the housing is a gasket 34 formed with ventilation openings 36 to dissipate heat from the housing interior when in use. The gasket 34 is lined and / or coated with a material which intumesces in the presence of excessive heat. During normal use, these openings 36 prevent overheating of the housing interior. In the event of a fire, however, the coating of intumescent material rapidly expands to close the openings. In a preferred arrangement a sealed thermoplastic tube filled with an extinguishing gas is positioned within each fire- proofed housing, the sealed tube operating to release liquid, gas or fluid in the event of a fire occurring within the housing to extinguish said fire within seconds.

Claims

1. 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.

2. An encloser as claimed in claim 1 wherein the housing comprises front, rear and side walls covered by a lid connected to the rear wall through a hinge.

3. An enclosure as claimed in any one of the preceding claims, wherein the internal scaffold is comprised of support members substantially located on the upper internal margin of the housing front and side walls.

4. An enclosure as claimed in claim 3, wherein the support members comprise elongate strips formed of stainless steel.

5. An enclosure as claimed in claim 2, 3 or 4, wherein the lid includes side pieces which extend downwardly from the upper margins of the front and side walls of the housing.

6. An enclosure as claimed in claim 5, wherein Velcro (RTM) tapes are substantially located on the upper external margin of the housing front and side walls and the reciprocal faces of the lid side pieces.

7. An enclosure as claimed in any one of the preceding claims wherein the housing 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 housing.

8. An enclosure as claimed in any one of the preceding claims, wherein housing includes a base on which on the respective battery locates.

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