Vehicle battery enclosure

Abstract

A vehicle battery enclosure comprises a housing (100, figure 1A) for a battery array; an emergency pressure equalization device 120 within the housing, the emergency pressure equalization device inclu

Description

TECHNICAL FIELD The present disclosure relates to a vehicle battery enclosure. Aspects of the invention relate to a vehicle battery enclosure, vehicle battery assembly and vehicle. BACKGROUND It is known to provide vehicle batteries within battery enclosures, which have accompanying emergency equalization pressure devices for reducing internal pressures within the battery enclosures in case of an undesirable battery event. Typically, undesirable battery events cause high energy to be released from the battery, leading to high temperatures and high pressures building up within the vehicle battery enclosure, for example as hot gases, flames and particles. It is an aim of the present invention to address one or more of the disadvantages associated with the prior art. SUMMARY OF THE INVENTION Aspects and embodiments of the invention provide a vehicle battery enclosure, a vehicle battery and a vehicle as claimed in the appended claims. According to an aspect of the present invention, there is provided a vehicle battery enclosure comprising: a housing for a battery array; a pressure equalization device within the housing, the pressure equalization device including a valve for exhausting fluids to outside the housing; and a thermal barrier comprising: a plate arranged within the housing and adjacent the valve, the plate including an aperture, and a guide configured to provide a tortuous flow path from the aperture to the valve. Advantageously, the thermal barrier helps to improve thermal management of the vehicle battery enclosure by controlling exhaustion of fluids, which may for example be relevant in undesirable battery events. The thermal barrier may prevent the battery enclosure venting very hot gases or flames to the external environment during an undesirable battery event, as well as controlling the direction of any hot fluids that are emitted. According to another aspect of the present invention there is provided a vehicle battery enclosure comprising: a housing for a battery array; an emergency pressure equalization device within the housing, the emergency pressure equalization device including a valve for exhausting fluids to outside the housing; and a thermal barrier comprising: a plate arranged within the housing and adjacent the valve, the plate including an aperture, and a guide arranged in a cavity defined between the housing and the plate, the guide configured to provide a tortuous flow path from the aperture to the valve. Advantageously, the thermal barrier provides a tortuous flow path between a battery cell and the valve that is longer than a direct flow path therebetween, so as to cause fluids in use to cool within the tortuous flow path. This is achieved by the aperture and the guide. Additionally, the plate of the thermal barrier acts as a baffle between the battery cell and the valve. In doing so, this helps to improve thermal management of the vehicle battery enclosure by controlling exhaustion of fluids, which may for example be relevant in undesirable battery events. In particular, the thermal barrier controls the emission of flames, particles and hot gases having a temperature greater than 500°C from being exhausted from inside to outside the housing. Optionally, the tortuous flow path is longer than a direct flow path between the at least one battery cell of the battery array and the valve. Optionally, the guide is arranged to make the tortuous flow path longer than a direct flow path between the battery cell and the valve. Optionally, the fluid flowing in the tortuous flow path is cooled to be less than 500°C before reaching the valve. Optionally, the tortuous flow path is configured to dissipate heat to cause fluid flowing in the tortuous flow path, in use, to cool. Advantageously, the thermal barrier improves thermal management by efficiently reducing the temperature of fluids before they reach the valve, which may for example be relevant in undesirable battery events, as well as shielding the valve from the high temperatures that may be exhausted by the battery array. Optionally, the guide is arranged to dissipate heat by providing the tortuous flow path as longer than the direct flow path between the battery cell and the valve. Optionally, the thermal barrier is arranged to dissipate heat by heat exchange. Optionally, the thermal barrier is configured to reduce heat transfer from the battery array to the valve. Optionally, the thermal barrier is configured to cool fluids flowing through the tortuous flow path by heat exchange by dissipating heat to the housing. Advantageously, the thermal barrier may improve thermal management. Optionally, the thermal barrier comprises aluminium. Optionally, at least one of the plate and the guide comprises aluminium. Optionally, the thermal barrier comprises stamped aluminium. Optionally, the thermal barrier is arranged to maintain its structural integrity under high heat conditions. Optionally, the thermal barrier is configured to be substantially unchanged under temperature conditions of up to approximately 2000°C for a duration of approximately 30 seconds. Advantageously, the thermal barrier may reduce the rate of heat transmission to the valve and maintain its structural integrity to withstand the high temperatures that may arise forthe duration of undesirable battery cell events. Furthermore, as a good conductor, the conductive properties of aluminium mean it may rapidly cool following heating to stay intact following an undesirable battery event. Optionally, the guide comprises at least one wall defining a channel arranged to provide the tortuous flow path. Advantageously, the channel acts to guide fluids, in use, through the tortuous flow path to efficiently cool fluids therein before they reach the valve. Optionally, the wall is a protrusion of at least one of the housing and the plate. Optionally, the wall is welded or bonded to at least one of the housing and the plate. Optionally, the wall is coupled to at least one of the housing and the plate. Optionally, the wall is in contact with an outer face of the plate, an inner face of the housing and a bottom of the housing. Advantageously, by contacting the wall to the respective surfaces of the plate and housing, the intersections between the wall and the housing and the plate are sealed such that the channel may efficiently guide fluids to the valve, and reduces the risk of fluids within the flow path seeping back into the housing for example when near the valve and of hotter fluids proximate the aperture from seeping to the valve without having traversed the tortuous flow path. Optionally, the wall is in contact with a tray of the housing. Optionally, the intersection between the wall and the plate is sealed. Optionally, the channel is substantially spiral-shaped. Optionally, the channel is shaped as a substantially rectangular spiral. Optionally, a portion of the wall is substantially U-shaped. Advantageously, a substantially spiral-shaped channel helps to lengthen the tortuous flow path as compared with a direct flow path between the battery array and the valve. Optionally, the plate is a baffle. Optionally, the plate is substantially planar. Optionally, the plate has an outer face arranged to face the valve and an inner face opposite the outer face arranged, in use, to face the battery array. Advantageously, the plate efficiently baffles fluids within the housing from the valve, and helps to improve thermal regulation by guiding fluids through the tortuous flow path via the aperture. Optionally, the area of the aperture is approximately the same as the area of the valve. Optionally, the thermal barrier is for reducing pressure within the vehicle battery enclosure. By providing the aperture with an area approximately the same as the area of the valve, the thermal barrier improves pressure regulation as the pressure within the battery pack may be reduced, since the aperture is less restrictive on the fluid flowing therethrough, as compared with the case where the aperture area is smaller than the valve area. Optionally, a central axis of the aperture is offset from a central axis of the valve. Optionally, the aperture is arranged in a substantially central portion of the plate. Optionally, the valve is arranged in a bottom corner of the housing. Advantageously, this configuration may help to improve lengthening the tortuous flow path as compared with a direct flow path between the battery pack and the valve. Optionally, the perimeter of the plate is arranged to provide a sealed border between the plate and the housing. Optionally, an intersection between the plate and housing is sealed. Optionally, an intersection between the plate and the wall is sealed. Advantageously, by providing a sealed border between the housing and the plate, the channel may efficiently guide fluids to the valve, whilst reducing the risk of fluids within the flow path (e.g. near the valve) seeping back into the housing and of hotter fluids proximate the aperture from seeping to the valve without having traversed the tortuous flow path. Optionally, the vehicle battery enclosure further comprises a gasket for providing the sealed border between the plate and the housing, and between the plate and the wall. Advantageously, the gasket may be sufficiently resistant to withstand the high heat conditions that may arise in an undesirable battery event to seal the intersection between the plate, the wall and the housing, so as to improve sealing of the intersections between the plate and the wall and between the plate and the housing in an undesirable battery event. Optionally, the gasket is configured to maintain its structural integrity under transient high temperature conditions. Optionally, the gasket comprises foam. Optionally, the gasket comprises one of silicon and a silicon compound. Optionally, the gasket is formed by extrusion or moulding. Optionally, a periphery of the plate is joined to the housing. Optionally, the plate is joined to the wall. The joining may be by welding or bonding, or any other suitable means. Optionally, the thermal barrier comprises fixing portions for coupling the thermal barrier to the housing. Advantageously, the thermal barrier may be structurally secured to the housing, and be sufficiently stable to both act as a baffle and guide fluids in use through the tortuous flow path. Optionally, the fixing portions are configured to couple the thermal barrier to an inner side of the housing. Optionally, the housing includes threaded holes and the fixing portions include holes in the sides of the plate for screws to extend therethrough to couple with the threaded holes of the housing. According to yet another aspect of the invention, there is provided a vehicle battery assembly comprising the vehicle battery enclosure as described herein and a battery array. Optionally, the battery array is housed within the cavity of the vehicle battery enclosure. According to a further aspect of the invention, there is provided a vehicle comprising the vehicle battery assembly as described herein. Optionally, the vehicle comprises a vehicle body, wherein the vehicle battery assembly is attached to the vehicle body. Optionally, the vehicle is a battery electric vehicle, a plug-in hybrid vehicle, or a mild hybrid vehicle. The vehicle battery assembly may be a primary or secondary energy source for vehicle propulsion. According to still another aspect of the invention, a method of manufacturing a vehicle battery enclosure is provided. The method comprises providing a housing for a battery array. The method comprises providing an emergency pressure equalization device including a valve for exhausting fluids to outside the housing. The method further comprises arranging a thermal barrier within the housing. Arranging the thermal barrier comprises arranging a plate within the housing and adjacent the valve. The plate includes an aperture. The arranging the thermal barrier further comprises providing a guide in a cavity defined between the housing and the plate. The guide is configured to provide a tortuous flow path from the aperture to the valve. Optionally, the method comprises coupling the thermal barrier to the housing. Optionally, coupling the thermal barrier to the housing comprises locating or driving screws through holes in the plate into threaded holes provided in the housing. Optionally, the method comprises forming holes dimensioned for the screws in the plate. Optionally, the method further comprises forming the thermal barrier. Optionally, the plate may be formed by pressing or casting aluminium. Optionally, the method comprises cutting a sheet of aluminium dimensioned to a cross-section of the housing. Optionally, the method comprises forming an aperture in the plate. Optionally, the method comprises forming a plurality of walls for providing the guide. Optionally, the method comprises coupling the walls to the housing. Optionally, the method comprises coupling the plate to the housing. Optionally, the method further comprises forming a gasket for sealing the intersection between the perimeter of the plate and the housing. Optionally, forming the gasket comprises a process of extruding or moulding foam configured to be maintain its structural integrity under transient high temperature conditions. Optionally, the method further comprises welding the perimeter of the plate to the housing. According to yet a further aspect of the invention, a method of manufacturing a vehicle battery assembly is provided comprising the method of manufacturing the vehicle battery enclosure as described herein and further comprising arranging a battery array in the vehicle battery enclosure. A fluid flow path is defined from at least one battery cell of the battery array to the valve, via the thermal barrier. Optionally, the battery array is arranged in the vehicle battery enclosure to house the battery array by arranging each battery cell of the battery array in a respective opening defined by the housing the vehicle battery enclosure. According to a still further aspect of the invention, a method of manufacturing a vehicle is provided comprising the method of manufacturing a vehicle battery assembly as described herein and further comprising attaching the vehicle battery assembly to a vehicle body. Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and / or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and / or features of any embodiment can be combined in anyway and / or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and / or incorporate any feature of any other claim although not originally claimed in that manner. BRIEF DESCRIPTION OF THE DRAWINGS One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1A shows a perspective representation of a vehicle battery enclosure according to embodiments of the invention; Figure 1B shows a zoomed-in front perspective representation of a thermal barrier of the vehicle battery enclosure of Figure 1A; Figure 1C shows a front perspective representation of a guide of the zoomed-in vehicle battery enclosure of Figure 1B; Figure 1D shows an exploded perspective representation of the zoomed-in vehicle battery enclosure of Figure 1B; Figure 1E shows a schematic representation of a tortuous flow path defined in the zoomed-in vehicle battery enclosure of Figure 1B; Figure 2 shows a flow chart of a method of forming a vehicle battery enclosure according to embodiments of the invention; and Figure 3 shows a vehicle comprising a vehicle battery assembly according to embodiments of the invention. DETAILED DESCRIPTION A vehicle battery enclosure 100 in accordance with an embodiment of the present invention is described herein with reference to the accompanying Figures 1A, 1B, 1C, 1D and 1E (collectively hereinafter referred to as Figure 1). Accompanying Figure 1 is Figure 3, which shows a vehicle 300 comprising a vehicle battery assembly 310. Figure 1A shows the vehicle battery enclosure 100 for housing a battery array (or battery pack) for a vehicle. An example of a vehicle 300 is shown in Figure 3. In particular, if a battery array is introduced into the vehicle battery enclosure 100 to provide a vehicle battery assembly 310, the vehicle battery assembly 310 may be attached to a vehicle body by suitable means in the art. Here, “body” may mean a monocoque which can have body panels attached thereto. The vehicle 300 may be any suitable vehicle adapted to be powered by a battery. For example, the vehicle 300 may be, although not limited to, a battery electric vehicle, a plug-in hybrid vehicle, or a mild hybrid vehicle. The vehicle battery assembly 310 may be a primary or secondary energy source for vehicle propulsion. With reference also to Figures 1B, 1C, 1D and 1E, the vehicle battery enclosure 100 comprises a housing 110, an emergency pressure equalization device 120 and a thermal barrier 130, including a plate 140 and a guide 160. Here, Figure 1B is presented as a zoomed-in front view of the thermal barrier 130 arranged in the vehicle battery enclosure 100. Figure 1C shows a guide 160 of the thermal barrier 130 of Figure 1B. Figure 1D illustrates an exploded view of Figure 1B. Figure 1E illustrates a tortuous flow path 190 defined by the thermal barrier 130 and guide 160 in Figure 1B in use. The housing 110 is for housing a battery array. The emergency pressure equalization device 120 is arranged within the housing 110 and includes a valve for exhausting fluids to outside the housing 110. The thermal barrier 130 comprises a plate 140 and a guide 160. The plate 140 is arranged within the housing 110 and adjacent the valve. The plate 140 includes an aperture 150. The guide 160 is arranged in a cavity defined between the housing 110 and the plate 140. The guide 160 is configured to provide a tortuous flow path 190 from the aperture 150 to the valve. In the present embodiment, the housing 110 comprises a frame 112 arranged to accommodate the valve of the emergency pressure equalization device 120, a tray 114 and a lid (not shown). Here, the frame 112 defines the sides of the housing 110, the tray 114 defines the bottom of the housing 110 and the lid defines the top of the housing 110, such that the housing 110 may be for enclosing a battery array. The frame 112 includes an aperture configured to accommodate the valve. As shown in Figure 1 A, the emergency pressure equalization device 120 (covered by the thermal barrier 130) is arranged toward a corner of the frame 112. The frame 112 also includes dividers defining openings 116 dimensioned to accommodate battery cells (not shown) such that the housing 110 is suitable for housing a battery array. It will be appreciated however that the disclosure is not limited to this, and the housing may accommodate the battery array by any suitable means. For example, in 6 some embodiments, the emergency pressure equalization device 120 may be arranged at any suitable location with respect to the housing 110. The valve of the emergency pressure equalization device 120 is configured to open to reduce internal pressure within the housing 110 when the internal pressure reaches a threshold. For example, the threshold may be reached when an undesirable battery event occurs (for example if a battery cell of the battery array undergoes a thermal runaway reaction and produces fluids) so that, in use, when the internal pressure increases and reaches the threshold, the valve is opened to release the built up internal pressure by exhausting fluids to outside the vehicle battery enclosure 100. In doing so, the emergency pressure equalization device 120 may rapidly reduce pressure within the vehicle battery enclosure 100, thereby improving pressure management of the vehicle battery enclosure 100. The thermal barrier 130 is arranged between the valve and the battery array, such that the valve is located in a part of the housing 110 defining the cavity. The thermal barrier 130 includes the plate 140 and the guide 160. As shown in Figure 1E, the tortuous flow path 190 is defined from the aperture 150 of the plate 140 to the valve of the emergency pressure equalization device 120. Here, “tortuous flow path” means a fluid flow path that is convoluted, such that the thermal barrier 130 acts to baffle the direct fluid flow path between the battery array and the valve. As such, the thermal barrier 130 positively shields the direct path of fluids from escaping the vehicle battery enclosure 110 via the valve such that, in use, fluid flowing in the tortuous fluid flow path 190 is cooled. Advantageously, the thermal barrier 130 provides a tortuous flow path 190 between a battery cell and the valve that is longer than a direct flow path therebetween, so as to cause fluids in use to cool within the tortuous flow path 190. In doing so, this helps to improve thermal management of the vehicle battery enclosure 100 by controlling exhaustion of fluids, which may for example be relevant in undesirable battery events. In doing so, the thermal barrier 130 may control the emission of flames, particles and hot gases having a temperature greater than 500°C from being exhausted from inside to outside the housing 110. The maximum temperature of the valve may therefore be reduced when the thermal barrier 130 is present. By contrast, under the same conditions but in the absence of the thermal barrier 130, the valve may be consistently higher in temperature and may even continue to increase in temperature. As such, in use, fluid flowing in the tortuous flow path 190 provided by the thermal barrier 130 may be cooled to be less than 500 °C before reaching the valve. In the present embodiment, the plate 140 of the thermal barrier 130 is a substantially planar baffle arranged to cover the emergency pressure equalization valve 120, and has an outer face and an inner face facing opposite the outer face, when mounted to the housing 110. The outer face of the plate 140 is arranged to face a portion of the housing frame 112 that includes the emergency pressure equalization device 120, so as to face the valve. The outer face of the plate 140 is separated from the frame 112 however, such that the plate 140 may define the cavity within which the guide 160 is arranged. The outer face of the plate 140 is coupled to the guide 160. The inner face of the plate 140 faces an inner region of the housing 110, so as to face, in use, the battery array. The plate 140 when coupled to the housing 110 is illustrated in Figures 1A and 1B, whereby the plate 140 is coupled to an inner side of the frame 112. In order to couple the plate 140 to the housing 110, the plate 140 has fixing portions including holes for receiving couplers 145 for coupling the plate 140 to the housing 110, and more particularly to an inner side of the frame 112. The fixing portions are arranged toward the sides of the plate 140, such that the plate 140 is coupled to the frame 112 by its sides. In the present embodiment, the fixing portions correspond to bent portions of the plate 140 that are arranged to contact or abut the inner side of the frame 112, so as to facilitate coupling of the thermal barrier 130 to the housing 110, whilst allowing the rest of the plate 140 to be a planar baffle that defines the cavity. In the present embodiment, the couplers 145 include screws, such that the plate 140 is coupled to the housing 110 by screwing the plate 140 to the frame 112 using a screw extending through each respective hole into a corresponding threaded hole (not shown) in the frame 112 of the housing 110. Advantageously, screwing holds the plate 140 in place securely in high temperatures, which is particularly relevant in the case of undesirable battery events resulting in the emission of high temperatures and pressures. It will of course be appreciated however that the disclosure is not limited to this, and in other embodiments, any suitable coupler, connector, or fixing mechanism such as welding or using an adhesive, known in the art, may be used to couple the plate 140 to the housing 110. The plate 140 entirely covers the valve of the emergency pressure equalization device 120, and includes the aperture 150, so as to allow fluids to flow from the battery array to the valve for reducing pressure within the vehicle battery enclosure. In the present embodiment, the area of the aperture 150 is approximately the same size as the area of the valve, which improves pressure regulation as the pressure within the battery pack may be reduced, since the aperture 150 is less restrictive on the fluid flowing therethrough, as compared with when the aperture area is smaller than the valve area. As illustrated in Figures 1B, 1C, 1D and 1E, a central axis of the aperture 150 is offset from a central axis of the valve, whereby the aperture 150 is arranged substantially centrally in the plane of the plate 140, whilst the valve is arranged in a bottom corner of the housing 110, and more particularly in a portion of the frame 112 proximate the tray 114. As such, in a plane orthogonal to the plane of the plate 140, the aperture 150 does not face or overlap the valve in the present embodiment, such that the valve is entirely covered by the plate 140 and faces a portion of the plate 140 that does not include the aperture 150. Advantageously, this configuration helps to lengthen the tortuous flow path 190 as compared with a direct flow path between the battery pack and the valve. In the present embodiment of the disclosure, the plate 140 includes a substantially smooth surface. However, the disclosure is not limited to this and in some examples of the disclosure, the plate 140 may include a surface indentation pattern comprising an array of peaks and depressions in a repeat cross-hatch pattern. Such surface indentation patterns may be formed by embossing the plate 140 using a press to provide an array of peaks and depressions. Turning now to the guide 160, Figure 1C shows the configuration of the guide 160 in the present embodiment, which is arranged in the cavity defined between the frame 112 of the housing 110 and the plate 140. The guide 160 is provided as a wall defining a channel arranged to provide the tortuous flow path 190 from the battery pack to the valve, via the aperture 150. In the present embodiment, the channel is shaped as a substantially rectangular spiral, with a portion of the channel being substantially U-shaped. Advantageously, a substantially spiral-shaped guide 160 helps to lengthen the tortuous flow path 190 as compared with a direct flow path between the battery array and the valve. This is for example shown in Figure 1E, which shows the flow of fluids through the tortuous flow path 190 as indicated by the arrow. In particular, fluids emitted from the battery pack, in use, enter the tortuous flow path 190 through the aperture 150 and are guided through the tortuous flow path 190 by virtue of the guide 160 in a spiral fashion before reaching the valve, where the fluids may then be exhausted through the emergency pressure equalization device 120 outside of the vehicle battery enclosure 100. The tortuous flow path 190 is longer than a direct flow path between the at least one battery cell of the battery array and the valve, by virtue of the spiral-shaped guide 160. In doing so, the thermal barrier 130 is arranged to reduce heat transfer from the battery array to the valve, as the tortuous flow path 190 causes fluid flowing therethrough, in use, to cool by dissipating heat via heat exchange to the housing 110. In doing so, the thermal barrier 130 improves thermal management by efficiently reducing the temperature of fluids before they reach the valve, which may for example be relevant in undesirable battery events, as well as shielding the valve from the high temperatures that may be exhausted by the battery array. In the present embodiment, the guide 160 protrudes from the frame 112 of the housing 110 to the plate 140. In the present embodiment, the guide 160 is integrally formed with the housing 110 (e.g. by casting) and is also coupled to the plate 140 by the couplers 145. It will be appreciated however that the disclosure is not limited to this, and in other examples of the disclosure, the guide 160 may be integrally formed with and / or coupled to at least one of the housing 110 and the plate 140, using suitable coupling means, such as by welding or joining techniques (e.g. bonding). As such, the guide 160 is in contact with the outer face of the plate 140, an inner face of the frame 112 and the tray 114 of the housing 110. Given that the temperatures emitted from the battery cells in an undesirable battery event may exceed 1200°C in some cases, the thermal barrier 130 is configured to maintain its structural integrity under transient high temperature conditions (such as those produced in an undesirable battery event) so as to be substantially unchanged under high temperature conditions of up to approximately 1200°C for a duration of approximately 30 seconds. In doing so, the thermal barrier 130 may remain largely chemically and structurally the same under high heat conditions maintaining its structural integrity throughout an undesirable battery event, and efficiently absorb heat via heat exchange. For example, the plate 140 and the guide 160 in the present embodiment comprise aluminium, which is configured to maintain its structural integrity under transient high temperature conditions. In practice, the thermal barrier 130 including aluminium may reduce the rate of heat transmission to the valve and maintain its structural integrity to withstand the high temperatures that may arise forthe duration of undesirable battery cell events. Furthermore, as a good conductor, the conductive properties of aluminium mean the thermal barrier 130 may rapidly cool following heating to stay intact following an undesirable battery event. However, the disclosure is not limited to this and in other embodiments, any suitable material for maintaining its structural integrity under transient high temperature conditions may be used in place of aluminium, such as an aluminium alloy, steel, or any other suitable metal or compound. In the present embodiment, a gasket is provided to seal the intersection between the plate 140 and the guide 160 and also between the plate 140 and the housing 110. In particular, the gasket is arranged to provide a sealed border around the perimeter of the plate 140 where the plate 140 contacts the housing 110 and particularly the tray 114 and the frame 112. The gasket is also arranged to seal the intersection between the plate 140 and the guide 160. By providing a sealed border between the plate 140, the housing 110 and the guide 160, the gasket helps to control the passage of fluids through the tortuous flow path 190, such that the tortuous flow path 190 may efficiently guide fluids to the valve, whilst reducing the risk of fluids within the tortuous flow path 190 (e.g. near the valve) seeping back into the housing 110 and of hotter fluids proximate the aperture 150 from seeping to the valve without having traversed the tortuous flow path 190. It will be appreciated that the disclosure is not limited to this however and in some examples of the disclosure, other suitable sealant techniques may be used to seal the intersections between the guide 160 and the housing 110, between the plate 140 and the guide 160 and between the plate 140 and the housing 110, such as suitable joining or attachment techniques. In other examples of the disclosure, the gasket or other suitable sealing technique is provided to seal the intersection between the guide 160 and the housing 110. In the present embodiment, the gasket is sufficiently resistant to withstand the high heat conditions that may arise in an undesirable battery event. In particular, the gasket comprises a suitable foam for maintaining its structural integrity under transient high temperature conditions, such as silicon ora silicon compound. The gasket may be formed by any suitable means, such as by extrusion or moulding. Figure 2 illustrates a method 200 according to an embodiment of the invention. The method 200 is a method of manufacturing a vehicle battery enclosure, such as the vehicle battery enclosure 100 illustrated in Figure 1. The method 200 comprises step 202 of providing a housing, such as the housing 110 illustrated in Figure 1. In some examples of the disclosure, the housing is provided by forming the housing using suitable techniques, such as pressing or casting aluminium to form a tray and a frame (such as the tray 114 and frame 112 in Figure 1), and connecting (e.g. by welding or bonding) a bottom of the frame to a perimeter of the tray. The method 200 comprises step 204 of providing an emergency pressure equalization device including a valve for exhausting fluids to outside the housing, such as the emergency pressure equalization device 120 described above in relation to the embodiment of Figure 1. In the present embodiment, step 204 includes forming a hole in the housing using a suitable hole forming technique, whereby the hole is dimensioned to the emergency pressure equalization device, and arranging the emergency pressure equalization device therein. In the context of Figure 1 A, the hole in the frame 112 is in the bottom corner of the housing 112 to accommodate the emergency pressure equalization device 120. It will be appreciated the disclosure is not limited to this. For example, the emergency pressure equalization device may first be provided, such that the housing may be formed around the emergency pressure equalization device and / or step 204 may include forming the emergency pressure equalization device using any valve forming technique. The method 200 further comprises arranging a thermal barrier within the housing, which includes step 206 of providing a guide and step 208 of arranging a plate. The thermal barrier 130 including guide 160 and plate 140 illustrated in Figure 1 is an example of the thermal barrier in the method 200. More particularly, step 206 includes providing a guide in a cavity defined between the housing and the plate, whereby the guide is configured to provide a tortuous flow path from the aperture to the valve. Step 208 includes arranging a plate within the housing and adjacent the valve, whereby the plate includes an aperture. In some embodiments, step 206 includes forming the guide to provide the guide. The guide 160 illustrated in Figure 1 is an example of the guide in the present method. In such embodiments, the guide is formed by pressing or casting aluminium to provide a substantially spiral-shaped wall, such as the wall described in relation to Figure 1. The wall is then joined by a suitable joining technique to the frame of the housing, for example by welding or bonding via a suitable adhesive. It will be appreciated that the disclosure is not limited to this and in other examples of the disclosure, the guide is formed integrally with the frame of the housing or with the plate. In some embodiments of the disclosure, step 208 further includes forming a plate so as to provide the plate to be arranged within the housing. In such examples of the disclosure, step 208 includes providing a sheet of material for maintaining structural integrity under transient high temperature conditions, such as an aluminium foil sheet, for example by pressing or casting aluminium. In such examples of the disclosure, step 208 comprises cutting the sheet of material according to predetermined dimensions, for example to a template predetermined by the dimensions of the cross-section of the housing, and forming an aperture (such as the aperture 150 in Figure 1), so as to provide a plate (such as the plate 140 in Figure 1). For example, in the context of Figure 1B, the sheet of material may be cut to the height of the frame 112 and a suitable width dimensioned for enabling the plate 140 to couple to the housing 110, define the cavity and cover the guide 160 and the emergency pressure equalization device 120. The aperture may be formed using a suitable holeforming tool substantially centrally within the plane of the plate. In some embodiments, step 208 further comprises forming bent fixing portions in the sides of the plate for subsequently coupling the plate to the housing. The fixing portions described in relation to Figure 1 are an example of the fixing portions in the present method, and may be formed using a suitable pressing technique. As part of forming the fixing portions, step 208 in such examples of the disclosure includes forming holes for receiving couplers (such as the couplers 145 in Figure 1) in the plate using a suitable hole-forming tool. For example, the holes are dimensioned to the couplers (e.g. screws) such that screws may extend therethrough to couple the plate to the housing, in use. Returning back to the method 200, following step 208 of arranging the plate within the housing, in some embodiments, the method 200 may further comprise a step (not shown) of coupling the plate to the housing. For example, a coupler may be used, such as the couplers 145 (e.g. screws) shown in Figure 1B. In such examples of the disclosure, the thermal barrier is coupled to the housing by locating or driving screws through holes arranged in sides or ends of the plate into threaded holes provided in the housing, for example the frame of the housing. In order to do so, threaded holes for receiving the screws may be formed in the housing, whereby the threaded holes are dimensioned to the screws. However, the disclosure is not limited to this and it will be appreciated that any suitable coupling means in the art may be used to couple or connect the thermal barrier to the housing. In some embodiments, the method 200 also comprises a step (not shown) of sealing the intersection between the perimeter of the plate and the housing and between the plate and guide. In the present embodiment, the above intersections are sealed using a gasket. The gasket described in relation to Figure 1 above is an example of the gasket in the present method. In some embodiments, the method 200 further comprises a step (not shown) of forming the gasket by a process of extruding or moulding foam configured to maintain its structural integrity under transient high temperature conditions. It will be appreciated however that the disclosure is not limited to this, and in other embodiments of the disclosure, other sealing techniques may be used, such as welding or bonding the perimeter of the plate to the housing and the plate to the guide. Although not shown, in some embodiments, a method of manufacturing a vehicle battery assembly may also be provided, which includes performing the method 200 of manufacturing the vehicle battery enclosure with an additional step (not shown) of arranging a battery array in the vehicle battery enclosure. The battery array may be arranged in the vehicle battery enclosure to house the battery array by arranging each battery cell of the battery array in a respective opening defined by the housing the vehicle battery enclosure. The vehicle battery assembly 310 in Figure 3 is an example of such a vehicle battery assembly. In further embodiments (not shown), a method of manufacturing a vehicle may also be provided, which includes the method described above of manufacturing the vehicle battery assembly and a further step of attaching the vehicle battery assembly to a vehicle body by any suitable means known in the art. The vehicle 300 shown in Figure 3 is an example of such a vehicle. It will be appreciated that various changes and modifications can be made to the present invention without departing from the scope of the present application.

Claims

1. A vehicle battery enclosure comprising:a housing for a battery array;an emergency pressure equalization device within the housing, the emergency pressure equalization device including a valve for exhausting fluids to outside the housing; anda thermal barrier comprising:a plate arranged within the housing and adjacent the valve, the plate including an aperture, anda guide arranged in a cavity defined between the housing and the plate, the guide configured to provide a tortuous flow path from the aperture to the valve.

2. The vehicle battery enclosure of claim 1, wherein the tortuous flow path is configured to dissipate heat to cause fluid flowing in the tortuous flow path, in use, to cool.

3. The vehicle battery enclosure of any one of the preceding claims, wherein the thermal barrier is configured to cool fluids flowing through the tortuous flow path by heat exchange with the housing so as to dissipate heat in the housing.

4. The vehicle battery enclosure of any one of the preceding claims, wherein the thermal barrier comprises aluminium.

5. The vehicle battery enclosure of any one of the preceding claims, wherein the guide comprises at least one wall defining a channel arranged to provide the tortuous flow path.

6. The vehicle battery enclosure of claim 5, wherein the wall is in contact with an outer face of the plate, an inner face of the housing and a bottom of the housing.

7. The vehicle battery enclosure of claim 5 or claim 6, wherein the channel is substantially spiralshaped.

8. The vehicle battery enclosure of any one of the preceding claims, wherein the plate is a baffle.

9. The vehicle battery enclosure of any one of the preceding claims, wherein the area of the apertureis approximately the same as the area of the valve.

10. The vehicle battery enclosure of any one of the preceding claims, wherein a central axis of the aperture is offset from a central axis of the valve.

11. The vehicle battery enclosure of any one of the preceding claims, wherein the perimeter of the plate is arranged to provide a sealed border between the plate and the housing.

12. The vehicle battery enclosure of claim 11, further comprising a gasket for providing the sealed border between the plate and the housing, and between the plate and the guide.5 13. The vehicle battery enclosure of any one of the preceding claims, wherein the thermal barriercomprises fixing portions for coupling the thermal barrier to the housing.

14. A vehicle battery assembly comprising the vehicle battery enclosure of any one of the preceding claims and a battery array.

015. A vehicle comprising the vehicle battery assembly of claim 14.15

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