EP4487406A1

EP4487406A1 - Safety system for vehicle propulsion battery pack

Info

Publication number: EP4487406A1
Application number: EP23711553.0A
Authority: EP
Inventors: Marco Aimo Boot
Original assignee: Iveco SpA
Current assignee: Iveco SpA
Priority date: 2022-03-02
Filing date: 2023-02-27
Publication date: 2025-01-08
Also published as: WO2023166397A1; CN118743083A; KR20240155190A; IT202200003902A1

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 conduit (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 duct (TB) in hydraulic communication with an internal compartment (IV) of the housing (H), in which the hydraulic duct is equipped with a first fitting (HI) for connection to an external source of extinguishing liquid and/ or coolant, wherein the tubular body comprises an emptying window (W) arranged between said fusible septum (FUSE) and said first fitting (HI).

Description

DESCRIPTION

"SAFETY SYSTEM FOR A VEHICLE PROPULSION BATTERY PACK"

★ ★ ★

Field of the invention

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 introduction of extinguishing liquid only when necessary .

State of the Art

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

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

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

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 .

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 .

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 .

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 .

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 .

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 .

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

Furthermore , it i s advisable to remove the inj ected liquid, making a special opening i f necessary .

It can be tricky to connect a hydraulic line to a vehicle ' s battery compartment , and even more so to drill an opening, while a thermal runaway is already triggered .

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 , where 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 .

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 .

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 .

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 i s equipped with an emptying window, which in the absence of a flow of extinguishing liquid and/or coolant from the relative source allows emptying, even i f only partial , of the housing towards the external .

In other words , the emptying window is arranged on a side wall of the tubular body of the duct , so as to put the inside of the battery compartment in communication with the external environment .

The emptying window also has the purpose of allowing a circulation of extinguishing liquid when there is a flow of extinguishing liquid and/or coolant from the relating source .

It is evident that the emptying window is a distinct and separate component from the fusible septum . The emptying window, arranged on a side wall of the hydraulic duct , exists at the origin, i . e . already before the fusible septum melts , precisely because the fusible septum and the emptying window are distinct and separate components that have completely di f ferent functions : the fusible septum puts the source of extinguishing liquid in communication with the internal compartment of the battery pack, while the emptying window puts both the source and the internal volume of the battery pack in communication with the external environment .

Preferably, the emptying window is oriented downwards , so as to facilitate emptying of the housing when the delivery of the coolant and/or extinguishing liquid is interrupted . Advantageously, it is not necessary to provide the housing with two openings . A single device allows to alternatively carry out a filling and emptying cycle of the housing, with ef fective heat removal .

Both the filling and emptying operations of the housing can be carried out by remotely controlling the flow of extinguishing liquid and/or coolant , i . e . without having to approach the vehicle to act on the faucet knob .

Obviously, the f low of the extinguishing liquid must be such as to allow the filling of the housing, despite the emptying window .

According to a variant of the invention, the emptying window can be opened and closed manually, limiting to a minimum the time in which an operator is close to the vehicle .

According to some variants of the invention, the device is equipped with a door arranged to automatically close said emptying window when the flow of extinguishing liquid and/or coolant towards the housing is interrupted . In this case , any further approach of an operator to the vehicle is completely eliminated .

According to a preferred variant of the invention, the device is equipped with a quick coupling to be easily and quickly connected to an external source of coolant and/or extinguishing liquid . There are di f ferent types of quick couplings , all of which are characteri zed by the fact that they allow immediate connection of two connectors without the use of tools and without long and laborious operations . For example , Storz connectors are considered quick couplings because with a simple combination of movements it is possible to make a hydraulic connection .

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

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

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 .

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

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 . Advantageously, thanks to this separation, the melting temperature of the fusible septum does not depend on the physical-chemical characteristics of the extinguishing liquid .

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

Brief description of the figures

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 :

Figs . 1 - 3 show an example of a hydraulic pipe equipped with a fitting compatible with a quick connection hydraulic system, respectively according to a perspective view, a side view and a view according to a longitudinal section;

Figs . 4 and 5 show a further variant of the invention according to a perspective and side view respectively, while figures 6a , 6b and 6c show three possible variants which, according to a longitudinal section of the device , which, externally, share the same shape shown in Figs . 4 and 5 ;

Fig . 7 shows a rear perspective view of the duct with a component common to all variants of the invention in evidence ;

Fig.8 shows a further preferred variant of the invention according to a longitudinal section;

Fig. 9 shows the application of the device according to any of the variants of the previous figures, applied to a housing for a battery pack.

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

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.

The elements and features 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 .

Detailed description

Fig. 1 shows a perspective view of a first preferred variant of the invention, while Fig.8 and Fig.4 in combination with Figs. 6a - 6c and 8 show other variants of the invention. The device D comprises a tubular duct TB intended to be fixed directly to a housing H of a battery pack, shown in Fig . 7 , by means of a flange FL stably fixed to a first end of the tubular body . At the second end, opposite to the first , of the tubular body, the device D comprises a fitting, preferably compatible with a quick coupling hydraulic system, schematically shown in Fig . 7 .

Alternatively, the tubular body is integral with the housing and therefore , the flange is not required .

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

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

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 .

According to a preferred variant of the invention, one of the fittings is equipped with a check valve arranged so as to open following the mutual connection of the two compatible fittings and to close following their mutual disconnection .

Equipping the quick coupling 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 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 .

The tubular body TB comprises an emptying window W disposed on a side wall of the tubular body TB .

This window is originally open to the outside , putting the external environment in communication with the volume inside the tubular body, upstream of the fusible septum . Thus , the internal compartment of the battery pack, downstream of the fusible septum, is sealed until a thermal runaway occurs .

With reference to Fig . 1 , the tubular body TB comprises a telescopic section comprising two portions OB, IB of which an external portion OB and an internal portion IB sliding axially internally to the external portion and in which one of the two portions is operatively associated with the flange or directly to the housing and the other portion is operatively associated with the first fitting HI . The telescopic section defines a compact configuration and an extended configuration, and in which, at least in the compact configuration, the tubular body is liquid-tight between the fitting HI and the flange or the housing HB, while , at least in the extended condition the body tubular allows the opening of the emptying window W .

According to the solution of Fig . 1 , the external portion OB is associated with the internal portion IB of the telescopic section by means of a bayonet coupling . The external portion comprises slots or grooves , i . e . blind slots , which al low the teeth TH fixed to the internal portion to move inside the slots or grooves between a compact configuration and an extended configuration . As with any bayonet coupling, the engagement is obtained through a combination of movements , first axial and then rotational .

Di f ferently from a common bayonet coupling, according to the solution of Fig . 1 it is not possible to completely disengage the two internal and external portions .

In the compact configuration, the window W is completely closed, as shown in Fig . 3 , conversely, in the extended configuration, the window W is completely wide open .

The window W is located at an intermediate point between the fusible septum FUSE and the fitting IH .

The expression " at an intermediate point" means that it coincides neither with the IH connection nor with the fusible septum FUSE .

This is advantageous , as it ensures that the internal compartment IV is kept hermetically separated from the external environment , regardless of the configuration assumed by the telescopic section of the tubular body TB .

In order for the fusible septum to melt , the melting temperature must be lower than the boiling temperature of the coolant and/or extinguishing liquid .

In fact , i f the housing is connected to an external source of refrigerant and/or extinguishing liquid, the liquid, in contact with the septum, prevents or slows down its melting, leading to an uncertainty of timely operation . In fact , 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 connection process of the source of coolant and/or extinguishing liquid with the battery compartment .

However, a septum that melts at a temperature suf ficiently lower than the boiling temperature of the coolant and/or extinguishing liquid may not be available or may not be suitable to satis fy the necessary mechanical characteristics . In fact , it must be taken into account that a vehicle is subj ect to vibrations in very di f ferent operating conditions .

Therefore , i f the septum were made with a material with a melting temperature comparable to or even higher than the boiling temperature of the coolant and/or extinguisher, the fact of having the coolant and/or extinguisher in contact with the septum could lead to device operation not as expected .

According to a preferred variant of the invention, see Figs . 4 and 6a, the tubular body TB comprises a door DR; DI , D2 disposed at an intermediate point between the fusible septum FUSE and the fitting HI and disposed for

- creating a seal with the tubular body and define a dry volume DV between the door DR itsel f and the fusible septum FUSE , when the fusible septum is intact , and for opening, placing the tubular duct ( TB ) in hydraulic communication with the compartment inside the housing H when the fusible septum is at least partially melted and at the same time

- closing the emptying window W .

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

The protruding portion EP of the septum emerges approximately perpendicularly with respect to the surface of the septum, to contact the door DR and keep it closed until the fusible septum itsel f breaks under the ef fect of the temperature .

Evidently, the pressure of the extinguishing liquid, applied to the door DR, contributes to the breaking of the fusible septum .

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

The variant of figure 6b di f fers from the variant of figure 6a, in that the emerging element EP is at least partially replaced by an elastic element , such as for example a spiral spring SP .

Figure 6c shows a further preferred variant of the invention, arranged to produce a dry volume . 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 door DI and D2 which define door DR 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 DR, 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 .

Preferably, each of the variants 6a - 6c is equipped with an emptying window W which puts the dry volume in communication with the external environment . As anticipated above , this window is useful for carrying out battery compartment filling and emptying cycles , increasing the ef fectiveness of battery cell cooling .

In the solution of Fig . 6c, the window W is even more advantageous , as it guarantees that , even i f the contact between the door D2 and the fusible septum is not perfectly sealed, the volume confined by the fusible septum, the portion D2 of the door and the tubular body never fills up with coolant and/or extinguishing liquid, ensuring that at least a portion of the fusible septum melts at the pre- established temperature .

For all variants 6a - 6c, after the fusible septum has broken, the portion D2 of the door opens completely going to close the window W, so that the device is approximately sealed .

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 bring the door D back into the closed position, allowing the window W to be crossed by the outflowing l iquid from the housing .

Also in the solutions of Figs . 6a and 6b, the window W can be arranged in such a way that , when the door DR is open, the window is completely closed, while when the door DR is closed, the window is completely open .

For this purpose , the opening of the door DR is opposed by at least one return spring S I , S2 . This spring is arranged to close the door and open the emptying window W wide . This is advantageous in order to be able to carry out the battery compartment filling and emptying cycles 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 .

It must be understood that when a thermal runaway occurs , it is highly dangerous to stand in the vicinity of the vehicle . Therefore , while the solution of figure 1 requires an operator to approach the vehicle , the solutions of figures 6a - 6c do not require an operator to approach the vehicle , since , to empty the battery compartment it is suf ficient to interrupt the remote coolant flow and/or extinguish . In fact , the emptying window opens automatically when there is no flow of coolant and/or extinguisher towards the battery compartment .

Fig . 7 shows the rear of the duct with the FL flange and the septum FUSE .

Fig . 8 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 dif fers from the variants of Figs . 6a - 6c in that the door is not hinged, but slides axially like a shutter .

Also in this case , the fusible septum, melting, breaks under the pressure of the extinguishing and/or coolant liquid and allows the door DR to advance towards the compartment allowing the coolant and/or extinguishing liquid to flood the battery compartment .

Preferably, the door, moving towards the battery compartment , closes the window W . However, the interruption of the liquid flow allows the return spring SP to recall the mobile unit back, completely opening the emptying window, so that the coolant and/or extinguishing liquid can flow out of the emptying window W .

Fig . 9 shows a housing BH with the relative internal volume IV, adapted to house a battery pack .

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 . 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 .

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 which may be released during a thermal runaway of at least one cell of the battery pack . When coolant is inj ected, the pressure relief valve opens , allowing coolant and/or extinguishing liquid to enter the internal compartment IV of the housing . 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 .

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

1. Safety system for vehicular propulsion battery pack, the system comprising a device (D) for the hydraulic connection of a housing (H) of a battery pack, the device (D) comprising a tubular duct (TB) equipped with a fusible septum ( FUSE ) , in such a way that, when a predetermined temperature threshold is exceeded, the septum melts putting the tubular duct (TB) in hydraulic communication with an internal compartment (IV) to the housing (H) , wherein the hydraulic duct is equipped with a first fitting (HI) for connection to an external source of extinguishing and/or refrigerant liquid, wherein the tubular body comprises an emptying window (W) arranged between said fusible septum (FUSE) and said first fitting (HI) .

2. System according to claim 1, further comprising said external source of extinguishing and/or refrigerant liquid and an external duct (PIP) equipped with a second fitting (CD) complementary to the first fitting (HI) , and wherein said first and second fitting define a quick hydraulic connection system.

3. System according to claim 2, wherein said first and second fittings are sexless.

4. System according to claim 2, 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 to 6 , 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 claim 7 , wherein the tubular body ( TB ) comprises a telescopic section comprising two portions ( OB, IB ) of which an external portion ( OB ) and an internal portion ( IB ) sl iding axially and inside the external portion and wherein one of said two portions is operatively associated with said flange or said housing and the other portion is operatively associated with the first fitting (HI ) and wherein the telescopic section defines a compact configuration and an extended configuration, and wherein, in said compact configuration, said emptying window is closed and the tubular body is liquid-tight and wherein, in said extended configuration, said emptying window is open .

9 . System according to claim 8 , wherein the external portion is associated with the internal portion by means of a bayonet coupling made in such a way as to allow said compact configuration and said extended configuration, without allowing the disengagement of the external portion from the internal portion .

10 . System according to claim 9 , wherein the inner portion ( IB ) comprises said emptying window (W) .

11 . System according to claim 7 , wherein said tubular body further comprises a door ( DR; 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 a dry volume ( DV) between the door and the fusible septum, when the fusible septum is intact , and to open, placing the tubular duct ( TB ) in hydraulic communication with the internal compartment ( IV) of the housing (H) , when the fusible septum is at least partially melted .

12 . System according to claim 11 , wherein said door, when open, is arranged to close said emptying window and vice versa, when closed is arranged to open said emptying window .

13 . System according to claim 12 , wherein the door is arranged to open moving towards the internal compartment of the housing (H) , and wherein the fusible septum comprises an emerging portion (EP ) so as to contact the door while keeping it in position closing and liquid-tight , interfering with an opening of the door as long as the septum is intact .

14 . A system according to claim 12 , wherein the door is arranged to open moving towards the internal compartment of the housing (H) , and wherein the fusible septum is arranged to support 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 .

15 . System according to claim 12 , wherein the door is arranged to open moving towards the internal compartment of the housing (H) , and wherein said door and said fusible septum are mutual ly 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 a liquid, so as to form a seal with the septum, defining said dry volume ( DV) and wherein said tubular body ( TB ) comprises a window (W) communicating with the external environment .

16 . System according to claim 12 , wherein the fusible septum is connected to the door by means of a spacer element (EP ) forming a single movable assembly, so as to define a dry volume ( DV) between the door and the fusible septum, 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 .

17 . 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 16 .

18 . A commercial or industrial vehicle comprising a housing for a vehicular propulsion battery pack according to claim 17 .

19 . Method of implementing a safety measure during a prolonged stop of an electric or electri fied vehicle according to claim 18 , comprising a step of connecting the housing (H) of the battery pack with an external source of extinguishing and/or refrigerant liquid .