Safety system for vehicle propulsion battery pack

Abstract

Safety system for vehicular propulsion battery pack, the system comprising a device (D) for hydraulic connection of a housing (H) of a battery pack, the device (D) comprising a tubular body (TB) equipped with a fusible septum (FUSE), in such a way that, when a predetermined temperature threshold is exceeded, the septum melts placing the tubular body (TB) in hydraulic communication with an internal compartment (IV) of the housing (H), in which the hydraulic duct is equipped with a first connection (HI), an external duct (PIP) connected to an external source of extinguishing liquid and / or coolant, and in which said device comprises a dry volume (VD) arranged so as to isolate the fusible septum from said extinguishing and / or coolant liquid until said predetermined temperature threshold is exceeded.

Description

[0001] DESCRIPTION

[0002] "SAFETY SYSTEM FOR VEHICLE PROPULS ION BATTERY PACK"

[0003] ★ ★ ★

[0004] Field of the invention

[0005] The present invention relates to the field of safety systems in the field of vehicular propulsion battery packs . In particular, the present invention relates generally to the introduction of extinguishing liquids into an electric vehicle battery casing, and more particularly to a fill door access system which allows the entry of extinguishing liquid only when necessary .

[0006] State of the art

[0007] The battery packs used with electric vehicles store large amounts of energy in a small space , resulting in high energy densities .

[0008] The battery case is often equipped with safety systems to improve safety and stability under abnormal operating conditions .

[0009] The phenomena that must be considered abnormal are the so- called thermal runaway . Phenomenon in which a large amount of heat and gas develops .

[0010] Such conditions can be caused by failure of a battery cell , ( such as overtemperature or overload events , or by mechanical damage , such as a collision that damages , by shorting, at least one of the cells in the battery pack . The heat released by the short can be quite large , depending on many factors , including the amount of energy converted to heat and the location of the short , can start a chain reaction .

[0011] When the temperature that develops exceeds a predetermined threshold which is approximately 200 ° C in relation to the construction characteristics of the cells , an irreversible chain reaction is triggered which leads to overheating and failure of the cells adj acent to the initially damaged one , releasing heat which, in turn, propadoors throughout the battery pack .

[0012] As a rule , the housing is equipped with a pressure relief valve which allows the evacuation of any gases released during the thermal dri ft , preventing the housing from exploding .

[0013] The housing also provides environmental protection from water / moisture ingress . To do this , the housing is designed as a sealed, rugged, metallic, thermoplastic or fiber- reinforced polymer enclosure .

[0014] It is di f ficult to control the chain reaction by inj ecting inert gases into the housing, because oxygen is released from some cathode materials of the battery during these reactions .

[0015] The most ef fective way to limit the ef fects of a thermal runaway is to remove the heat by inj ecting extinguishing liquid into the housing .

[0016] However, this means having to connect an external source of extinguishing liquid to the battery pack .

[0017] It can be tricky to connect a hydraulic line to a vehicle battery compartment when a thermal runaway has already started .

[0018] When considering an electric vehicle charging station or simply a room where an electric vehicle is stored, any delay in extinguishing a thermal runaway in the early stages of development can turn into a catastrophe , as the fire can spread to adj acent vehicles and / or infrastructure . In addition, normal fire- fighting systems may not be suf ficient to deal with similar circumstances , in which the so-called fire load is very high as in the case of commercial or industrial electric vehicles , which are equipped with signi ficant energy storage .

[0019] The Applicant is aware of a duct equipped with a fusible septum, which allows the introduction of an extinguishing liquid and / or coolant into the battery housing when, following the achievement of a predetermined temperature threshold, the septum melts .

[0020] Unless speci fically excluded in the detailed description that follows , what is described in this chapter is to be considered as an integral part of the detailed description .

[0021] Summary of the invention The obj ect of the present invention is to provide the housing with a safety system which allows easier and more immediate intervention in the event of a thermal runaway of a cell of a battery pack of an electric or electri fied vehicle .

[0022] The basic idea o f the invention is to provide the battery pack housing with a hydraulic conduit equipped with a fusible septum, so that when the septum melts due to a thermal runaway, the hydraulic conduit is in communication with the compartment inside the housing, in which the hydraulic duct is equipped with a dry volume , arranged to isolate the fusible septum from the extinguishing and / or coolant liquid, until the temperature threshold is exceeded, so as to ensure that the septum is not cooled by the extinguishing liquid and / or coolant .

[0023] Advantageously, this fact allows the hydraulic pipe to be kept hydraulically connected to a source of cooling and / or extinguishing liquid, without risking that the septum does not melt as it is refrigerated by the same extinguishing and / or cooling liquid in direct contact .

[0024] More speci fically, when the septum melts , the dry volume automatically ceases to exist , allowing the coolant and / or extinguishing liquid to reach the battery pack, without any external intervention .

[0025] According to a preferred variant o f the invention, the duct is equipped with a quick-type hydraulic fitting . There are di f ferent types of quick fittings , all of which are characteri zed by the fact that they allow immediate connection of two fittings without the use of tools and without long, dangerous and laborious operations .

[0026] For example , Storz fittings are considered quick fittings because with a simple combination of movements it is possible to make a hydraulic connection .

[0027] There are quick fittings that define a system called "water-stop" , i . e . configured to interrupt the flow of liquid when the two complementary fittings are separated . An example of such fittings is in WO9919657 .

[0028] According to a preferred variant of the invention, the fitting connected to the battery pack housing is compatible with a water-stop system .

[0029] In a plug-socket system it is evident that the shut-of f valve is mounted inside one of the two fittings , typically on the female fitting, however, the male fitting, while not equipped with the valve , must not only be configured to engage the female fitting, making a hydraulic connection, but also to release the valve contained therein . Therefore , the concept of compatibility implies that the fitting must be such as to make a hydraulic connection and simultaneously release the valve present in one of the two fittings . Although the fitting associated with the housing is not itsel f equipped with a valve , it is compatible with a fitting equipped with a valve to create a water-stop system .

[0030] Advantageously, the vehicle can be rapidly associated with a source of extinguishing liquid without having to perform laborious and dangerous manoeuvres , especially in emergency conditions .

[0031] Thanks to the present invention, it is possible to keep any parked vehicle , for example during a battery recharging procedure , permanently connected to a source of extinguishing liquid and / or coolant .

[0032] Advantageously, the water-stop system defined between the battery pack hous ing and the source of extinguishing liquid and / or coolant makes mutual interconnection even faster, favouring the safety of electric or electri fied vehicles . According to a further preferred aspect of the invention, the duct is made in such a way as to define a separation between the fusible septum and the extinguishing liquid . According to a further aspect of the invention, the device is equipped with a valve able to open automatically when a flow of extinguishing liquid and / or coolant towards the housing is interrupted, allowing to carry out filling and emptying cycles o f the housing, without having to reali ze a second opening . Advantageously, thanks to this separation, the melting temperature of the fusible septum does not depend on the physical-chemical characteristics of the extinguishing liquid .

[0033] The dependent claims describe preferred variants of the invention, forming an integral part of the present description .

[0034] Brief description of the figures

[0035] Further obj ects and advantages of the present invention will become clear from the detailed description that follows of an embodiment of the same ( and of its variants ) and from the annexed drawings given for purely explanatory and non-limiting purposes , in which :

[0036] Figs . 1 and 2 show a variant of the invention according to a perspective and side view respectively, while figures 3a , 3b and 3c show three possible variants which according to a longitudinal section of the device , which, externally, share the same shape shown in figures 1 and 2 ;

[0037] Fig . 4 shows a rear perspective view of one of the variants of the device ;

[0038] Fig . 5 shows a longitudinal section of another preferred variant of the invention;

[0039] Fig . 6 shows the application of the device of the present invention, applied to a housing for a battery pack; Figs. 7 and 8 show further preferred variants of the invention respectively according to a longitudinal section and a perspective view.

[0040] The same reference numbers and letters in the figures identify the same elements or components or functions.

[0041] It should also be noted that the terms "first", "second", "third", "superior", "inferior" and the like may be used herein to distinguish various items. These terms do not imply a spatial, sequential, or hierarchical order for the modified items unless specifically indicated or inferred from the text.

[0042] The elements and characteristics illustrated in the various preferred embodiments, including the drawings, can be combined with each other without however departing from the scope of protection of the present application as described below .

[0043] Detailed description

[0044] The device D comprises a tubular body TB intended to be affixed directly on a housing H of a battery pack, shown in figure 6, by means of a flange FL stably fixed to a first end of the tubular body. At the second end, opposite to the first one, of the tubular body, the device D comprises a hydraulic fitting HI compatible with a quick interconnection hydraulic system, schematized in figure 6, where a duct PIP is shown, which connects an external source of coolant and / or or extinguishing liquid to the housing, by means of the hydraulic system D, CD .

[0045] Alternatively, the tubular body is integral with the housing and therefore , the flange FL is not required .

[0046] There are di f ferent types of quick fittings , all of which are characteri zed by the fact that they allow immediate connection of two fittings without the use of tools and without long and laborious operations .

[0047] For example , Storz fittings are considered quick fittings , because with a simple combination of movements it is possible to make a hydraulic connection between two compatible fittings . Storz fittings are also called " sexless" as the two fittings of the interconnection system are identical to each other .

[0048] Other solutions envisage , for example , having to withdraw a ring nut of the female fitting to allow the male fitting to be disengaged from the female fitting .

[0049] According to a preferred variant of the invention, one of the fittings is equipped with a non-return valve arranged so as to open following the mutual connection o f the two compatible fittings and to close following their mutual disconnection .

[0050] Equipping the rapid interconnection hydraulic system INTC with a "water stop" system is very advantageous , as it speeds up the safety of an electric or electri fied vehicle . The tubular body TB comprises a fusible septum FUSE fixed perimetrically to the tubular body . This septum has the task of keeping the internal compartment TV of the housing BH of the battery pack hermetically separated from the external environment . So that , only in the event of a thermal runaway, it is possible to inj ect water into the housing .

[0051] When the melting temperature of the septum is higher than the boiling temperature of the extinguishing liquid, the septum does not melt or melts at a higher temperature than expected with a signi ficant delay in the process of connecting the source of coolant and / or extinguishant with the battery compartment .

[0052] According to the present invention, see figures 1 and 3a, 3b, 3c and 5 , the tubular body TB comprises a door DI , D2 arranged at an intermediate point between the fusible septum FUSE and the fitting HI and arranged for

[0053] - creating a seal with the tubular body and define a dry volume DV between the door itself and the fusible septum, when the fusible septum is intact , and for opening, placing the tubular body TB in hydraulic communication with the compartment inside the housing H when the fusible septum is at least partially melted .

[0054] The door D is preferably formed by two doors DI and D2 , each hinged to the tubular body, so as to open towards the internal compartment of the housing .

[0055] The emerging door EP of the septum emerges approximately perpendicular to the surface of the septum, to contact door D and keep it closed until the fusible septum itsel f breaks due to the temperature .

[0056] Evidently, the pressure of the extinguishing liquid, applied to door D, contributes to the breaking of the fusible septum .

[0057] Therefore , on the one hand, door D allows the creation of a dry volume between the coolant and / or extinguishing liquid and the fusible septum, while , on the other hand, door D contributes to the detachment of the fusible septum when it begins to yield due to of a thermal runaway of the battery pack .

[0058] The variant of figure 3b di f fers from the variant of figure 3a, in that the emerging element EP is at least partially replaced by an elastic element , such as for example a spiral spring SP .

[0059] Figure 3c shows a further preferred variant of the invention, arranged to produce a dry volume .

[0060] It can be seen from the figure that there is no interference element fixed on the fusible septum . In this case , the two portions of the door DR : DI and D2 have a di f ferent extension . In particular, the portion D2 of the door is wider than the portion DI of the same door . In addition, the fusible septum and the door D, as a whole , are arranged at such a distance that the portion D2 interferes with the fusible septum FUSE , as long as this is intact . In other words , the portion D2 fails to open completely due to the ef fect of the pressure of the extinguishing liquid and / or refrigerant .

[0061] Preferably, each of the variants 3a - 3c is equipped with an emptying window W which puts the dry volume in communication with the external environment . This emptying window is useful for performing battery compartment filling and emptying cycles , increasing the ef fectiveness of battery cell cooling .

[0062] In the solution o f figure 3c, the emptying window W is even more advantageous , as it guarantees that , even i f the contact between the portion D2 and the fusible septum is not perfectly sealed, the volume confined by the fusible septum, the door D2 of the door and the tubular body never fills with cooling and / or extinguishing liquid, guaranteeing that at least a portion of the fusible septum melts at the pre-established temperature .

[0063] After the fusible septum is broken, the portion D2 of the door opens completely going to close the emptying window W, not necessarily reali zing a perfect seal .

[0064] When the delivery of the coolant and / or extinguishing liquid is interrupted to carry out the filling and emptying cycles of the battery pack, the return springs S I and S2 are arranged to return the positions DI and D2 of the door to closing, allowing the emptying window W to be crossed by the liquid flowing out of the housing .

[0065] Also in the solutions of figures 3a and 3b, the emptying window W can be arranged in such a way that , when the door DR is open, the emptying window is completely closed, while when the door DR is closed, the emptying window is completely open .

[0066] For this purpose , the door DR is brought back to closure by at least one return spring S I , S2 when the pressure generated by the source of extinguishing liquid and / or coolant ceases .

[0067] This aspect is advantageous in order to be able to perform the alternating cycles of filling and emptying the battery compartment only by interrupting the flow of extinguishing liquid and / or coolant , without disconnecting the duct PIP connecting the source of extinguishing liquid and / or coolant from device D .

[0068] It must be considered that when a thermal runaway occurs , it is highly dangerous to stand in the vicinity of the vehicle . Thanks to the present invention, it is not necessary for an operator to approach the vehicle , since , to empty the battery compartment , it is suf f icient to remotely interrupt the flow of the coolant and / or extinguish liquid . In fact , the emptying window opens automatically when there is no flow of coolant and / or extinguisher towards the battery compartment .

[0069] Figure 5 shows a further variant of the invention, in which the fusible septum is connected to the door by means of a spacer element EP forming a single mobile unit - door DR, fusible septum FUSE and spacer element EP - , so as to define a dry volume DV between the door and the fusible septum . This variant di f fers from the variants o f figures 3a - 3c in that the door is not hinged, but runs axially like a shutter .

[0070] Also in this case , the fusible septum, melting, yields under the pressure of the extinguishing and / or cooling liquid and allows the door to advance , opening to the passage of the extinguishing and / or cooling liquid . Preferably, the door DR, moving towards the battery compartment - on the left of the figure - , closes the emptying window W . However, the interruption of the liquid flow allows the return spring SP to recall the mobile unit back, opening the emptying window W, so that the coolant and / or extinguishing liquid can flow out of the emptying window W .

[0071] Figure 6 shows a housing BH with the relative internal volume IV, adapted to house a battery pack .

[0072] The device D is f ixed in a lower part of the housing, which in the figure is shown connected to a duct PIP by means of a fitting CD compatible with the fitting HI of the device .

[0073] The lower part is considered as such in relation to the operating condition of the hous ing, so that the cooling and / or extinguishing liquid can naturally flow out due to the gravitational force .

[0074] Preferably, the emptying window W is arranged, where present , so as to look downwards , so as to facil itate the emptying of the housing when the delivery of the coolant and / or extinguishing liquid is interrupted .

[0075] Therefore , considering the housing of the battery pack in operating configuration, figures 7 and 8 show a further preferred variant of the invention . This is the only variant without the emptying window .

[0076] Here the tubular body TB is S-shaped and the fitting HI is in a lower position than the fusible septum FUSE . This means that when the duct PIP is hydraulically connected to the device D, air remains trapped between the fitting HI and the fusible septum FUSE , forming a separation wall with the front of the coolant and / or extinguishing liquid .

[0077] This variant provides , among other things , also an breaking invitation TF which facilitates the breaking of the fusible septum from below .

[0078] It should be noted that the housings of the vehicle battery packs are equipped with an overpressure valve (not shown) arranged to allow the evacuation of gases that may be released during a thermal runaway of at least one cell of the battery pack . When coolant is inj ected pressure relief valve opens , allowing coolant and / or extinguishing liquid to enter internal compartment IV of housing .

[0079] Variants of the non-limiting example described are possible , without however departing from the scope of protection of the present invention, including all equivalent embodiments for a person skilled in the art , to the contents of the claims .

[0080] From the description given above , the person skilled in the art is capable of reali zing the obj ect of the invention without introducing further constructive details .

Claims

CLAIMS1. Safety system for vehicular propulsion battery pack, including the system- a device (D) for the hydraulic connection of a housing (H) of a battery pack, the device (D) comprising a tubular body (TB) equipped with a fuse septum (FUSE) , so that, upon exceeding a predetermined temperature threshold, the septum is arranged to melt, putting the tubular body (TB) in hydraulic communication with an internal compartment (IV) to the housing (H) , in which the hydraulic pipe is equipped with a first fitting (HI) ;- an external duct (PIP) connected to an external source of extinguishing and / or refrigerant liquid, wherein the external duct comprises a second connection (CD) complementary to the first connection (HI) , and wherein said device comprises a dry volume (VD) arranged so as to isolate the fusible septum from said extinguishing and / or refrigerant liquid until said predetermined temperature threshold is exceeded.

2. System according to claim 1, wherein said first and second fittings define a rapid hydraulic connection system.

3. System according to claim 1, wherein said first and second fittings are sexless.

4. A system according to claim 1, wherein said first fitting is male and said second fitting is female.5 . System according to claim 4 , wherein the quick hydraulic connection system is of the water-stop type .6 . The system according to claim 5 , wherein a check valve is associated with the second fitting and arranged to open only when the second fitting is operatively connected to the first fitting .7 . System according to any one of the preceding claims 1 to6 , wherein said device ( D) is integral with said housing or fixable by means of a flange ( FL ) integral with the tubular body .8 . System according to any one of the preceding claims 1 -7 , wherein said tubular body further comprises a door ( D; DI , D2 ) arranged at an intermediate point between said fusible septum and said first fitting and arranged to- create a seal with the tubular body and define said dry volume ( DV) between the door and the fusible partition, when the fusible septum is intact , and to open, placing the tubular body ( TB ) in hydraulic communication with the internal compartment ( IV) of the housing (H) , when the fuse septum is at least partially melted .9 . System according to claim 8 , wherein the door is arranged to open moving towards the internal compartment of the housing (H) , and wherein the fuse septum comprises an emerging door (EP ) so as to contact the door and keep it inposition closing and liquid-tight , interfering with an opening of the door as long as the septum is intact .10 . A system according to claim 8 , wherein the door is arranged to open moving towards the internal compartment of the housing (H) , and wherein the fuse septum is arranged to supdoor a closing spring ( LS ) so as to contact the door keeping it in the closed and liquid-tight position, so as to interfere with the opening of the door as long as the septum is intact .11 . System according to claim 8 , wherein the door is arranged to open moving towards the internal compartment of the housing (H) , and wherein said door and said fuse septum are mutually spaced and wherein the door comprises a return spring ( S I , S2 ) arranged to keep the door in the normally closed position and wherein the door is configured to contact the fuse ( FUSE ) , when the duct is pressuri zed with said coolant and / or extinguishing liquid, so as to form a seal with the septum, defining said dry volume ( DV) and wherein said tubular body ( TB ) comprises an emptying window (W) communicating with the external environment .12 . System according to any one of claims 9 to 11 , wherein said tubular body comprises a emptying window (W) arranged at an intermediate point between said door and said fusible septum and wherein said door is arranged to close said emptying window (W) when it opens due to a flow of coolantand / or extinguishing liquid and said return spring is arranged to bring said door closed when said flow of coolant and / or extinguishing liquid is interrupted .13 . System according to claim 8 , wherein the fusible septum is connected to the door by means of a spacer element (EP ) forming a single movable assembly, so as to def ine a dry volume ( DV) between the door and the fusible partition, and wherein the tubular body is shaped so that when the fusible septum is melted, the mobile unit is able to slide towards the housing (H) putting the first fitting (HI ) in hydraulic communication with the internal compartment ( IV) of the housing and wherein a retraction spring ( SP ) is arranged to retract towards the first fitting, the single movable assembly .14 . System according to any one of claims 1 to 7 , wherein said tubular body is S-shaped so that , in operating conditions , it retains an air bubble defining said dry volume .15 . Housing (H) for a vehicular propulsion battery pack comprising a device ( D) for the hydraulic connection of the housing (H) to an external source of extinguishing and / or refrigerant liquid, according to any one of claims 1 to 14 .16 . Housing (H) for a vehicular propulsion battery pack comprising a device ( D) for the hydraulic connection of the housing (H) to an external source of extinguishing and / orrefrigerant liquid, according to claim 20 , wherein, in operating conditions the first fitting is in a lower position than the septum ( FUSE ) fuse .17 . A commercial or industrial vehicle comprising a housing for a vehicular propulsion battery pack according to claim 15 or 16 .18 . Method of implementing a safety measure during a prolonged stop of an electric or electri fied vehicle according to claim 17 , comprising a step of connecting the housing (H) of the battery pack with an external source of extinguishing and / or refrigerant liquid by means of said device ( D) .

Images