Fire barrier closure assembly for a battery pack and battery pack comprising such closure assembly

Abstract

There is described a closure assembly (6) configured to be coupled to a battery pack (2) of a vehicle (1), in particular an electric or hybrid vehicle (1), for closing and sealing an opening (5) obtained in an outer casing (3) of the battery pack (2), the closure assembly (6) comprises: a support frame (7) made of rigid material and configured to be fixed on the casing (3) at the opening (5); a lid member (8) made of elastomeric material and coupled to the support frame (7) so as to cover, close and seal the opening (5); the lid member (8) includes a first surface (8a) configured to face the opening (5), when the support frame (7) is fixed on the casing (3), and a second surface (8b) opposite the first surface (8a); the lid member (8) is releasably coupled to the support frame (7) and is configured to detach from the support frame (7) by means of a predetermined pressure exerted onto the second surface (8b), thereby allowing access into the casing (3) through the opening (5)

Description

[0001] FIRE BARRIER CLOSURE ASSEMBLY FOR A BATTERY PACK AND

[0002] BATTERY PACK COMPRISING SUCH CLOSURE ASSEMBLY

[0003] TECHNICAL FIELD

[0004] The present invention relates to a closure assembly for closing and sealing an opening obtained in a casing of a battery pack, in particular a battery back for the use in an electric or hybrid vehicle .

[0005] BACKGROUND ART

[0006] Battery cells are known, which are used as electrical energy accumulators .

[0007] In particular, so-called primary batteries are known, which cannot be easily recharged and are therefore destined to single-use , and so-called secondary batteries are known, which can be repeatedly charged after each cycle of usage .

[0008] Single-cell batteries of the secondary type are known which are used for various portable small-si zed electronic devices , such as cellular phones , watches , smartwatches , smart bands , etc .

[0009] Also , battery packs which include a plurality o f cells connected in series or in parallel are known, for example as used in the automotive industry .

[0010] The present invention will refer to a battery pack of a hybrid or full-electric vehicle , for example an electric car, without however losing generality .

[0011] A single battery cell typically comprises a hollow housing, for example in the shape of a hollow parallelepiped and usually made of metallic material , generally open on at least one side ( for example on the top ) and a lid assembly for closing the casing .

[0012] The housing internally defines an inner compartment of the cell and houses the cell electrodes ( cathode and anode ) , which are provided for example in the form of sheets , and a separator material electrically interposed between the electrodes .

[0013] Within the compartment , the electrodes and the separator are immersed in an electrolytic material , usually liquid or gelatinous .

[0014] The lid assembly is coupled to the housing at an opening thereof for closing the inner compartment in a fluid-tight manner, thereby maintaining electrodes and separator in place and preventing the outflow of the electrolytic material .

[0015] A typical battery pack essentially comprises a casing and a plurality of such battery cells housed in the casing .

[0016] As it is known, the unlikely event of an ignition within one or more battery cells may occur, which may lead to a development of a fire within the battery pack casing .

[0017] In such a case , the casing must ensure both that the flames are temporarily contained, for example for a reasonable amount of time necessary for the fire rescue reaching the battery pack, and that the inside of the casing is made accessible to a fire extinguishing medium .

[0018] To this end, the casing typically presents an opening which defines a passage for the extinguishing medium reaching the inside of the casing, and therefore the battery cells and the flames .

[0019] During nominal operation, the aforementioned opening must be kept closed and sealed .

[0020] In this regard, the battery pack usually comprises a lid or cover which closes the opening, thereby sealing the inside of the casing from the outer environment .

[0021] In particular, the known lids have a breakable membrane which is configured to be ruptured by a high- pressure j et of extinguishing product .

[0022] According to a first known solution, the lid, or at least the breakable membrane , is made of metal .

[0023] However, a metallic lid is costly to produce and requires a rather malleable metal , such as aluminum . Moreover, aluminum is not able to withstand high temperatures for long, and may collapse in a relatively short time , e . g . before the extinguishing medium is provided .

[0024] Furthermore , a metallic lid ( for example made of aluminum) conduces electricity, which increases the risk of short circuit during normal use .

[0025] In addition, the rupture of a metallic breakable membrane is not controllable and may not be as uni form as desired, thereby leading to a suboptimal f low of extinguishing medium inside the casing .

[0026] Moreover, such lids are rather fragile and may rupture during use due to a known pressure rise caused by a gas development inside the casing ( e . g . thermal runway of one or more cells ) .

[0027] According to a second known solution, the lid is entirely made of an elastomeric material like PP, PTFE or VMQ .

[0028] However, albeit being less costly and easier to manufacture , such lids are not able to withstand high temperatures , thereby increasing the risk of fire hazard .

[0029] Moreover, such lids are not very stable and may pop out or even rupture due to thermal runway .

[0030] DISCLOSURE OF INVENTION

[0031] It is therefore an obj ect of the present invention to provide a closure assembly for a battery pack which is designed to overcome at least one of the above-mentioned drawbacks in a straightforward and low-cost manner . This obj ect is achieved by a closure assembly as claimed in the appended independent claim 1 . Preferred embodiments of the present invention are laid down in the appended dependent claims .

[0032] BRIEF DESCRIPTION OF THE DRAWINGS

[0033] A non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings , in which :

[0034] Figure 1 shows , with parts removed for clarity, a vehicle comprising a battery pack including an opening in its casing and a closure assembly according to the present invention which closes and seals such opening;

[0035] Figure 2 is a larger-scale side view, with parts removed for clarity, of the battery pack and the closure assembly of Figure 1 ; and

[0036] Figure 3 is a larger-scale perspective view, with parts removed for clarity, of the closure assembly according to the present invention .

[0037] BEST MODE FOR CARRYING OUT THE INVENTION

[0038] With reference to Figure 1 , number 1 indicates as a whole a vehicle , preferably a full-electric or hybrid vehicle , such as a car, a van, or the like .

[0039] Vehicle 1 is equipped with a battery pack 2 , which in Figure 1 is only schematically shown .

[0040] Battery pack 2 is of the known type and includes an outer casing 3 and a series of battery cells 4 housed within the casing .

[0041] Battery cells 4 are schematically depicted in Figure 3 .

[0042] Each battery cell 4 is of the known type and includes a housing which internally defines a compartment containing electrodes ( cathode and anode ) and a separator . The electrodes and the separator are immersed in an electrolytic solution .

[0043] Each battery cell 4 may be a prismatic battery cell .

[0044] Alternatively, each battery cell 4 may be a cylindrical battery cell .

[0045] In one embodiment , battery cells 4 may be of the pouch type .

[0046] Casing 3 has an opening 5 . Opening 5 defines a passage for a fire-extinguishing medium to enter the inner environment delimited by casing 3 and thereby reaching battery cells 4 and any other electric component housed within casing 3 .

[0047] In this way, in the unlikely event of a fire developing inside casing 3 , the flames can be reached and extinguished .

[0048] During nominal operation, i . e . during the normal li fespan of vehicle 1 and battery pack 2 , opening 5 must be kept closed and sealed, in order to avoid dirt or other undesired bodies or substances entering casing 3 .

[0049] To this end, battery pack 2 comprises a closure assembly 6 , shown in its entirety in Figure 2 .

[0050] Closure assembly 6 is configured to be coupled to battery pack 2 so as to close and seal opening 5 .

[0051] In particular, in use , closure assembly 6 is coupled to casing 3 at opening 5 , and therefore is coupled to battery pack 2 , so as to close and seal opening 5 .

[0052] This is schematically depicted in Figure 3 .

[0053] Closure assembly 6 comprises : a support frame 7 made of rigid material and configured to be fixed on casing 3 at opening 5 , in particular fixed in use on casing 3 at opening 5 ; and

[0054] - a lid member 8 made of elastomeric material and coupled to support frame 7 so as to cover, close and seal opening 5 .

[0055] According to the non-limiting embodiment shown, support frame 7 is substantially plate-shaped and lid member 8 is substantially disc-shaped .

[0056] Moreover, support frame 7 has a through hole , in particular a central through hole , laterally delimited by an inner wall 10 of support frame 7 .

[0057] Lid member 8 engages the through hole cooperating in contact with inner wall 10 .

[0058] More speci fically, lid member 8 has an outer wall 11 which cooperates in contact with inner wall 10, preferably with interference.

[0059] Furthermore, closure assembly 6 has a central axis A. Preferably, the through hole is axial, i.e. extends in the axial direction, and lid member 8 axially engages the through hole.

[0060] In this way, lid member 8 is coupled with support frame 7.

[0061] Preferably, support member 7 is fixed to casing 3 by means of screws 12 (Figure 2) , or by any other suitable fastening means, such as rivets, bolts, glue, etc.

[0062] Screws 12 or other type of releasable fastening means are preferable for improving assemblability and / or production flexibility and simplicity of battery pack 2.

[0063] As visible in Figure 3, lid member 8 includes a first surface 8a configured to face opening 5, and therefore the inner environment of casing 3, when support frame 7 is fixed on casing 3, and a second surface 8b opposite first surface 8a, and configured to face an environment external to casing 3 and battery pack 2.

[0064] Therefore, in use, i.e. when closure assembly 6 is coupled with battery pack 2, first surface 8a faces towards opening 5 and second surface 8b faces outwardly.

[0065] Preferably, first surface 8a and second surface 8b are axial surfaces, with respect to axis A. According to an aspect of the present disclosure , lid member 8 is releasably coupled to support frame 7 and is configured to detach from support frame 7 by means of a predetermined pressure exerted onto second surface 8b, thereby allowing access into casing 3 through opening 5 .

[0066] In other words , closure assembly 6 is configured such that lid member 8 detaches , in use , from support frame 7 by means of said predetermined pressure exerted onto second surface 8b, thereby allowing access into casing 3 through opening 5 , i . e . freeing the passage defined by opening 5 .

[0067] More precisely, lid member 8 is configured to detach from support frame 7 by means of the predetermined pressure exerted by the aforementioned fire-extinguishing medium onto second surface 8b, thereby allowing entrance of the fire-extinguishing medium into casing 3 through opening 5 .

[0068] In particular, lid member 8 is configured to detach from support frame 7 by means of a pressure higher than a predetermined threshold pressure value exerted onto second surface 8b . That is , i f the pressure exerted on second surface 8b is below the threshold value , lid member 8 does not detach from support frame 7 and stays coupled thereto .

[0069] In other words , closure assembly 6 is configured to be controlled, by means of said predetermined pressure exerted on second surface 8b, from a closed configuration ( shown in the appended Figures ) , in which lid member 8 is coupled to support frame 7 and seals opening 5 , to an open configuration (not shown) , in which lid member 8 is detached from support frame 7 and frees opening 5 .

[0070] Conveniently, lid member 8 is configured to completely detach from support frame 7 .

[0071] More speci fically, after lid member 8 is detached from support frame 7 , lid member 8 and support frame 7 are completely separated from one another .

[0072] Preferably, and due to the fact that second surface 8b faces outwardly, lid member 8 is configured to fall inside casing 3 by means of the aforementioned detachment , while support member 7 stays in place in its fixed position on casing 3 .

[0073] In light of the above , a safe and stable closure of opening 5 is obtained, due to the two-piece configuration of closure assembly 6 , which entails the presence of a rigid support frame 7 and a flexible elastomeric lid member 8 detachable form support frame 7 under the action of the fire-extinguishing medium, such as high-pressure water .

[0074] In particular, the rigid support frame 7 ensures a stable , robust and firm coupling of closure assembly 6 to battery pack 2 , able to withstand vibrations occurring during use of vehicle 1 and able to maintain its position relative to opening 5 of casing 3 .

[0075] At the same time , lid member 8 easily detaches from support member 7 when needed, completely freeing the passage defined by opening 5 and without leaving any obstructing portion which may hinder the passage of the fire-extinguishing medium .

[0076] In this regard, the overall safety of battery pack 2 is increased .

[0077] Moreover, there are no breakable parts in closure assembly 6 , since the lid member 8 simply detaches from support frame 7 without rupturing . Hence , in the remote case of an accidental pressure applied on second surface 8b which exceeds the predetermined pressure threshold value and which causes the lid member 8 to detach from support member 7 , lid member 8 can be put again in place without the need for substituting the entire closure assembly 6 or without the need for a new lid member 8 .

[0078] In one embodiment , vehicle 1 includes a fire extinguishing medium inlet obtained on an external hull thereof and a duct which fluidically connects such inlet with closure assembly 6 , and in particular with membrane portion 14 .

[0079] This facilitates access to opening 5 . According to a further aspect of the present disclosure , lid member 8 is made of an elastomeric material comprising silicone rubber and one or more of the following components :

[0080] - basalt fibers ;

[0081] - glass fibers ;

[0082] - a non- flammable reinforcing filler ;

[0083] - an endothermic flame retarder including aluminum hydroxide .

[0084] In a preferred embodiment , lid member 8 is made of a material having a composition comprising :

[0085] - less than 57 % by weight of silicone rubber,

[0086] - less than 29% by weight of the endothermic flame retarder including aluminum hydroxide , preferably Apyral® ATH,

[0087] - less than 6% by weight of basalt fiber,

[0088] - less than 3% by weight of glass fiber, less than 6% by weight of the non- flammable reinforcing filler, based on the total weight of the composition .

[0089] The Applicant has observed, by means of an extensive experimental campaign, that flame resistance of closure assembly 6 wherein lid member 8 is made of the aforementioned material is largely improved, in particular with respect to a metal lid or cover and / or to a simple PP, PTFE or VMQ lid or cover like the one described in the introductory portion of the present description .

[0090] Thus , the safety degree of closure assembly 6 is improved, as well as the overall safety of battery pack 2 and vehicle 1 .

[0091] Advantageously, support frame 7 is made of rigid thermoplastic material including a filler comprising glass fibers and a flame retardant .

[0092] In a preferred embodiment , support frame 7 is made of a material comprising : a ) a polymer matrix of crosslinking an aliphatic polyketone with at least one diamine source as a crosslinking agent to form imine groups and wherein the diamine source is selected from the group consisting of oligo- / polymers containing at least two amide groups ,

[0093] - saturated alicyclic compounds having at least two primary amine groups , an oligo- / polymers containing these incorporated and

[0094] - mixtures thereof ; b ) at least one flame retardant .

[0095] In particular, the flame retardant is selected from : inorganic compounds of phosphorus , magnesium, calcium, boron, aluminum, antimony, tin, zinc, organic phosphorus compounds, red phosphorus, organic nitrogencontaining compounds, organic halogen compounds and mixtures thereof; and / or

[0096] - Mg (OH) 2, phosphates, polyphosphates, phosphites, phosphinates, phosphonites, phosphoric and phosphonic acid esters, phosphazenes or mixtures thereof.

[0097] Preferably, the support frame (7) material comprises the flame retardant in amount of 5 to 30 % by weight based on the total weight of the polymer matrix.

[0098] Preferably, support frame 7 is (entirely) made of Quantix Ultra®, produced and commercialized by the same Applicant .

[0099] In this way, a strong and robust fixing of support frame 7 to casing 3, and therefore a strong, robust and stable coupling of closure assembly 6 to battery pack 2, is obtained, while at the same time increasing the fire resistance of closure assembly 6. In fact, such material, i.e. Quantix Ultra®, is able to withstand high temperatures for a rather long time, more than often sufficient for the fire rescue to timely act.

[0100] As visible in Figure 3, lid member 8 comprises:

[0101] - a coupling portion 13 coupled to support frame 7 in a releasable manner; and a membrane portion 14 integral with coupling portion 13 and configured to cover opening 5. In particular, coupling portion 13 has a substantially tubular shape and is arranged coaxially to axis A. That is , coupling portion 13 extends in the axial direction .

[0102] According to the non-limiting embodiment shown, membrane portion 14 is circular-shaped, and in particular is arranged coaxially with axis A.

[0103] More in particular, membrane portion 14 extends in the radial direction and extends from an upper portion of coupling portion 13 , so that the resulting assembly has an overturned cylindrical cup shape .

[0104] Preferably membrane portion 14 and coupling portion 13 are made in one single piece without solution of continuity .

[0105] In this way, assembling of closure assembly 6 and its mounting on battery pack 2 are simpli fied .

[0106] Conveniently, first surface 8a and second surface 8b are defined on membrane portion 14 .

[0107] In this way, membrane portion 14 defines a pressurereceiving portion of lid member 8 .

[0108] More precisely, membrane portion 14 is configured to gather the pressure exerted by the fire-extinguishing medium, which ultimately causes the detachment of lid member 8 .

[0109] This configuration ensures a smooth detachment of lid member 8 , avoiding an undesired and rather hazardous stay in place of lid member 8 during a fire emergency .

[0110] As said, outer wall 11 of lid member 8 cooperates in contact , and preferably with interference , with inner wall 10 of support frame 7 , thereby defining the ( axial ) engagement of lid member 8 in the through hole of support frame 7 .

[0111] As visible in Figure 3 , outer wall 11 is carried by, i . e . is defined on, coupling portion 13 , so as to radially face inner wall 10 .

[0112] Advantageously, support frame 7 includes at least one groove 15 obtained on inner wall 10 and extending in the radial direction with respect to axis A, and coupling portion 13 includes at least one rib 16 protruding from outer wall 11 in the radial direction .

[0113] Rib 16 engages groove 15 in a releasable manner .

[0114] In this way, the coupling of lid member 8 with support frame 7 is more stable and firmer, while at the same time being releasable and easily detachable under the aforementioned predetermined pressure threshold value .

[0115] In other words , the engagement of rib 16 into groove 15 increases the stability of the coupling between lid member 8 and support frame 7 during use of vehicle 1 .

[0116] For example , resistance of such coupling against vibrations is enhanced .

[0117] Preferably, rib 16 extends circumferentially on outer wall 11 , and more in particular extends completely without interruption about axis A.

[0118] Similarly, groove 15 extends circumferentially on inner wall 10 , and more in particular extends completely without interruption about axis A.

[0119] This configuration ensures an even more stable coupling between lid member 8 and support frame 7 , avoiding mispositioning and an undesired displacement of lid member 8 during use , e . g . due to vibrations .

[0120] Expediently, rib 16 defines a sealing lip configured to fluid-tight seal opening 5 at a portion of contact between lid member 8 and support frame 7 .

[0121] In this way, the risk of leaks from casing 3 through opening 5 and / or entrance of external entities into casing 3 through opening 5 is highly reduced .

[0122] That is , the fluid-tight sealing of closure assembly 6 is improved .

[0123] According to an alternative embodiment not shown, support frame 7 may include a plurality of grooves 15 of the aforementioned type , and lid member 8 , and more speci fically coupling portion 13 thereof , may include a plurality of ribs 16 of the aforementioned type , each rib 16 engaging a corresponding groove 15 . In this way, stability and strength of the coupling between lid member 8 and support frame 7 is further enhanced, as well as the fluid-tight sealing thereat .

[0124] As visible in Figures 2 and 3 , support frame 7 has an inner surface 7a configured to face towards casing 3 , when closure assembly 6 is coupled to battery pack 2 , and an outer surface 7b opposite inner surface 7a .

[0125] That is , inner surface 7a faces casing 3 , in use .

[0126] Advantageously, coupling portion 13 further includes a retaining portion 17 extending over inner surface 7a and abutting against inner surface 7a for preventing a detachment of lid member 8 from support frame 7 by means of a pressure exerted onto first surface 8a .

[0127] In particular, retaining portion 17 extends in the radial direction and abuts against inner surface 7a along the axial direction .

[0128] More in particular, retaining portion 17 is made in one single piece without solution of continuity with coupling portion 13 .

[0129] In this way, assembling of closure assembly 6 and its mounting on battery pack 2 are simpli fied .

[0130] Even more in particular, retaining portion 17 extends from a lower portion of coupling portion 13 .

[0131] Therefore , lid member 8 has a substantially omegashaped cross section, with retaining portion 17 defining the lower wings of the omega .

[0132] The presence of retaining portion 17 as described above further improves the stabi lity and the robustness of the coupling of lid member 8 and support frame 7 , without however adding any other component which could hinder the passage of the fire-extinguishing medium or complicating the assembling and the architecture of closure assembly 6 .

[0133] In fact , in some known cases , a development of gas can take place within one or more battery cells 4 , for example during a so-called thermal runway event .

[0134] Hence , an internal pressure could build up within casing 3 .

[0135] The presence of retaining portion 17 highly reduces the risk of lid member 8 detaching outwardly from support frame 7 due to this internal pressure .

[0136] In light of the above , retaining portion 17 acts as a stopper for lid member 8 against a displacement along the outwardly axial direction .

[0137] Conveniently, closure assembly 6 further includes a sealing member 18 fitted to support frame 7 at inner surface 7a and configured to cooperate in contact with casing 3 and to be interposed between inner surface 7a and casing 3 for fluid-tight sealing opening 5 .

[0138] In particular, sealing member 18 defines a further sealing lip of closure assembly 6 for sealing the contact zone between casing 3 and support frame 7 .

[0139] In this way, the fluid-tight sealing of closure assembly 6 is further improved, not only against fluids but also against dirt , dust or any other external substance which could contaminate battery pack 2 .

[0140] The advantages of closure assembly 6 , and of the battery pack 2 comprising such closure assembly 6 , according to the present invention will be clear from the foregoing description .

[0141] In particular, a safe and stable closing of opening 5 is obtained, due to the two-piece configuration of closure assembly 6 , which entails the presence of a rigid support frame 7 and a flexible elastomeric lid member 8 detachable form support frame 7 under the action of the fire-extinguishing medium, usually fed at high-pressure .

[0142] More in particular, the rigid support frame 7 ensures a stable , robust and firm coupling of closure assembly 6 to battery pack 2 , able to withstand vibrations occurring during use of vehicle 1 and able to maintain its position relative to opening 5 of casing 3 .

[0143] At the same time , lid member 8 easily detaches from support member 7 when needed, completely freeing the passage defined by opening 5 and without leaving any obstructing portion which may hinder the passage of the fire-extinguishing medium .

[0144] In this regard, the overall safety of battery pack 2 is increased .

[0145] Moreover, thanks to the peculiar materials of which lid member 8 and support frame 7 are made , fire resistance of closure assembly 6 is largely improved with respect to the known closures for openings 5 pf casings 3 of battery packs 2 .

[0146] It is also to be considered that a closure assembly 6 according to the invention is easier to manufacture than a metallic lid or cover .

[0147] Clearly, changes may be made to closure assembly 6 , and to the battery pack 2 comprising such closure assembly 6 , as described herein without , however, departing from the scope of protection as defined in the accompanying claims .

Claims

CLAIMS1.- Closure assembly (6) configured to be coupled to a battery pack (2) of a vehicle (1) , in particular an electric or hybrid vehicle (1) , for closing and sealing an opening (5) obtained in an outer casing (3) of the battery pack (2) , the closure assembly (6) comprising:- a support frame (7) made of rigid material and configured to be fixed on the casing (3) at said opening (5) ;- a lid member (8) made of elastomeric material and coupled to the support frame (7) so as to cover, close and seal said opening (5) ; wherein the lid member (8) includes a first surface (8a) configured to face the opening (5) , when the support frame (7) is fixed on the casing (3) , and a second surface (8b) opposite the first surface (8a) ; and wherein the lid member (8) is releasably coupled to the support frame (7) and is configured to detach from the support frame (7) by means of a predetermined pressure exerted onto said second surface (8b) , thereby allowing access into the casing (3) through said opening (5) .2.- Closure assembly as claimed in claim 1, wherein the lid member (8) is configured to detach from the support frame (7) by means of a predetermined pressure exerted by a fire-extinguishing medium onto said secondsurface (8b) , thereby allowing entrance of the fireextinguishing medium into the casing (3) through said opening (5) .3.- Closure assembly as claimed in claim 1 or 2, wherein the lid member (8) is configured to detach from the support frame (7) by means of a pressure higher than a predetermined threshold pressure value exerted onto said second surface (8b) .4.- Closure assembly as claimed in any one of the foregoing claims, wherein the closure assembly (6) is configured to be controlled, by means of said predetermined pressure exerted on said second surface (8b) , from a closed configuration, in which the lid member (8) is coupled to the support frame (7) and seals said opening (5) , to an open configuration, in which the lid member (8) is detached from the support frame (7) and frees the opening (5) .5.- Closure assembly as claimed in any one of the foregoing claims, wherein the lid member (8) comprises:- a coupling portion (13) coupled to the support frame (7) in a releasable manner; and- a membrane portion (14) integral with the coupling portion (13) and configured to cover said opening (5) ; wherein said first surface (8a) and said second surface (8b) are defined on the membrane portion (14) .6.- Closure assembly as claimed in claim 5, and having a central axis (A) , the coupling portion (13) extending in the axial direction and the membrane portion (14) extending in a radial direction with respect to the central axis (A) , wherein the support frame (7) has an axial through hole laterally delimited by an inner wall (10) of the support frame (7) , the coupling portion (13) of the lid member (8) axially engaging said through hole cooperating in contact with the inner wall (10) , the support frame (7) including a groove (15) obtained on the inner wall (10) and extending in the radial direction with respect to the central axis (A) , the coupling portion (13) having an outer wall (11) cooperating in contact with the inner wall (10) and including a rib (16) protruding from the outer wall (11) in the radial direction; and wherein the rib (16) engages the groove (15) in a releasable manner.7.- Closure assembly as claimed in claim 6, wherein said rib (16) defines a sealing lip configured for fluid- tight sealing said opening (5) at a portion of contact between the lid member (8) and the support frame (7) .8.- Closure assembly as claimed in any one of the claims 5 to 7, wherein the support frame (7) has an inner surface (7a) configured to face towards the casing (3) ofthe battery pack (2) , when the closure assembly (6) is coupled to the battery pack (2) , and an outer surface (7b) opposite the inner surface (7a) ; and wherein the coupling portion (13) includes a retaining portion (17) extending over said inner surface (7a) and abutting against said inner surface (7a) for preventing a detachment of the lid member (8) from the support frame (7) by means of a pressure exerted onto said first surface (8a) .9.- Closure assembly as claimed in claim 8, and having a central axis (A) , wherein said retaining portion (17) extends in a radial direction, with respect to the central axis (A) , and abuts against said inner surface (7a) along the axial direction .10.- Closure assembly as claimed in any one of the foregoing claims, wherein the support frame (7) has an inner surface (7a) configured to abut against the casing (3) of the battery pack (2) , when the closure assembly(6) is coupled to the battery pack (2) , and an outer surface (7b) opposite the inner surface (7a) ; and wherein the closure assembly (6) further includes a sealing member (18) fitted to the support frame(7) at said inner surface (7a) and configured to cooperate in contact with the casing (3) and to be interposedbetween the inner surface (7a) and the casing (3) for fluid-tight sealing said opening (5) .11.- Closure assembly as claimed in any one of the foregoing claims, wherein the support frame (7) has a through hole and the lid member (8) is substantially discshaped and releasably engages the through hole of the support frame (7) .12.- Closure assembly as claimed in any one of the foregoing claims, wherein the support frame (7) is made of rigid thermoplastic material including a filler comprising glass fibers and a flame retardant.13.- Closure assembly as claimed in any one of the foregoing claims, wherein the lid member (8) is made of an elastomeric material comprising silicone rubber and one or more of the following components:- basalt fibers;- glass fibers;- a non-flammable reinforcing filler;- an endothermic flame retarder including aluminum hydroxide .14.- Battery pack (2) comprising:- an outer casing (3) ;- one or more battery cells (4) housed within the casing ( 3 ) ;- an opening (5) obtained in the casing (3) ; and- a closure assembly (6) as claimed in any one of the foregoing claims and coupled to the battery pack (2) so as to close and seal the opening (5) .15.- Electric or hybrid vehicle (1) comprising a battery pack (2) as claimed in claim 14.

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