Ventilation device for battery

Abstract

The invention discloses a battery system. The invention relates to a battery system comprising a battery housing having a vent (18) and a venting device (12, 12 ', 12 ") and a venting device (12, 12', 12") comprising a first membrane (24, 24 ', 24 ") adapted to ensure a pressure equalization between the interior of the battery housing (14) and its environment in a normal operating state of the battery system, and a second membrane (26, 26', 26") adapted to ensure a pressure equalization between the interior of the battery housing (14) and its environment in a normal operating state of the battery system. The second membrane (26, 26 ', 26' ') is adapted to ensure emergency ventilation in the event of a technical defect in the battery system (10).

Description

Technical Field

[0001] The invention relates to a ventilation device for a battery and in particular to a ventilation device for a housing of a battery submodule, a battery module or a battery system, the ventilation device being configured to be integrated in the housing. More particularly, the invention relates to a device for balancing the internal pressure of a housing, in particular a battery housing of a motor vehicle, with the ambient pressure of the housing. Furthermore, the invention relates to a battery system comprising such a ventilation device. Background Art

[0002] In the housing (or casing) of a battery system, particularly a high voltage battery system such as those used in motor vehicles, temperature and pressure variations result in a pressure differential between the housing of the battery system and the environment.

[0003] In normal operation, these pressure differentials must be balanced. In order to provide thermal control of the enclosed components, a thermal management system may be used to effectively dissipate, exhaust and / or dissipate the heat generated within the enclosure. If such a thermal management system is omitted, or heat dissipation from the enclosure is not adequately performed, an increase in internal temperature may result in abnormal reactions occurring therein.

[0004] Furthermore, especially in high-voltage battery systems with large capacities, there is a risk that one or more cells in the battery fail due to overloading or other technical defects. This can generate large amounts of harmful gases that must be discharged in a controlled manner. Therefore, in the event of a technical defect in the battery, emergency ventilation must be provided.

[0005] One can use two different devices to perform both functions, pressure compensation in normal operation and emergency ventilation in case of technical defects. However, the two devices increase the weight of the assembly and the maintenance.

[0006] Document DE102017214754A1 discloses a device that combines two functions. The device includes a pressure balancing element. The pressure balancing element has an element body and a membrane arranged on the element body. The device includes a connecting element for connecting the pressure compensation element to the housing in a gas-tight manner. When the internal pressure is lower than the limit pressure, the element body rests on the connecting element in a gas-tight manner. In addition, when the internal pressure is greater than the limit pressure, the element body opens a hole for exchanging gas.

[0007] US2021396324 discloses a ventilation component attached to a housing at a vent of the housing, the ventilation component comprising a breathable membrane and a vent valve, the vent valve comprising an elastic body and a structural member, the elastic body is opened and closed by elastic deformation of the elastic body, and the structural member supports the breathable membrane and the vent valve. The structural member is arranged between the housing and the cap of the ventilation component.

[0008] EP3617570A1 relates to a ventilation unit, comprising a first ventilation body and a second ventilation body, wherein the first ventilation body allows gas to flow from the interior of a housing to the exterior of the housing when the internal pressure is higher than the external pressure. The first ventilation body and the second ventilation body are connected to a structural support member, which is arranged in a cavity of the housing of the ventilation unit.

[0009] US2018292020A1 discloses a pressure compensation device for a housing, the housing having an air port covered by a breathable membrane and a pressure relief valve. The breathable membrane and the pressure relief valve are both arranged in a grid-shaped cage. The cage consists of an inner half 20 forming the housing and an outer half 21 forming a cap. The breathable membrane and the pressure relief valve are both connected to the housing.

[0010] This device is suitable for handling the pressure compensation function with the main body of the element and the emergency ventilation with the membrane. However, there is still a need to improve this device. Summary of the invention

[0011] One object of the present invention is to provide a ventilator which performs two functions (emergency ventilation in case of damage and compensation of pressure differences in normal working conditions) and which is robust, easy to manufacture, install and maintain and has as few parts as possible. Another object of the present invention is to provide a ventilator which exhibits satisfactory performance in terms of humidity management and service life.

[0012] Therefore, the present disclosure relates to a venting device for a battery according to claim 1 , wherein the battery housing has a venting opening, and to a battery system according to claim 14 .

[0013] More specifically, the ventilation device comprises a housing, a cap cooperating with the housing, extending above the housing, and a first membrane suitable for ensuring pressure balance between the interior of the battery system and its environment in normal operating conditions of the battery system. The device also comprises a second membrane suitable for ensuring emergency ventilation in the event of a technical defect in the battery system, wherein the cap comprises a first section connected to the first membrane and a second section connected to the second membrane. The cap is thus connected to both membranes, which makes it easy to install and maintain the valve. The cap thus has two functions, protecting the interior of the housing and assembling the membranes.

[0014] In one embodiment, the first membrane is a gas permeable membrane. Therefore, the membrane can easily ensure pressure balance under normal circumstances.

[0015] In one embodiment, the cap is ultrasonically welded to the first membrane. Ultrasonic welding ensures a secure fixation and is easy to achieve. The weld is therefore airtight.

[0016] In one embodiment, the second membrane is press fit between the housing and the cap. The press fit has high connection strength and vibration resistance. Assembly can be automated and is reliable and consistent. In addition, the connection has the ability to resist thermal expansion during thermal cycling. In one embodiment, the second membrane is movable between an open position and a closed position, wherein the second membrane automatically moves back to its closed position when the excess pressure disappears.

[0017] In one embodiment, the cap is generally circular, having a central portion adapted to be covered by the first film and an outer annular portion adapted to be partially covered by the second film. The cap is integral, but ensures different functions depending on the portion attached to the first film or the second film. In one embodiment, the first film covers the central portion and the outer annular portion. In other words, in one embodiment, the first film extends above the second film.

[0018] In one embodiment, the central portion comprises a plurality of ventilation holes. The ventilation holes face the first membrane to ensure a correct pressure balance.

[0019] In one embodiment, the second outer annular portion comprises a plurality of openings which are regularly distributed, are curved, and face the second membrane.

[0020] In one embodiment, the cap comprises a rim at least partially covering the periphery of the housing.Thus, the cap is a protective cover and can surround the housing.

[0021] In one embodiment, the central portion comprises an edge extending longitudinally from the inner surface along the longitudinal axis, wherein the edge defines one or more cavities. The edge forms a structure that enhances the rigidity of the device.

[0022] In one embodiment, the first film is fixed to the edge. The edge forms a surface and the first film can be easily fixed to the surface.

[0023] In one embodiment, the breather device further comprises a sealing ring extending around the housing. The sealing ring is adapted to sealingly fix the breather device to the housing.

[0024] In one embodiment, the second membrane is annular. In one embodiment, the first membrane has a disc shape. In one embodiment, the first membrane extends substantially in the center of the second membrane. Thus, a compact arrangement is provided.

[0025] In one embodiment, the first membrane is made of polyethylene terephthalate (PET) or polytetrafluoroethylene (PTFE) material, which has high strength to weight ratio and moisture resistance.

[0026] In one embodiment, the second membrane is made of an elastomer or a thermoplastic elastomer. The size, shape or flexibility of such materials can be customized.

[0027] In one embodiment, the cover and / or the cap and / or the housing is made of a metal material, so that it can better resist high temperatures.

[0028] In one embodiment, the cover is adapted to automatically pop out from the cap under overpressure. In other words, the fixing of the cover to the cap is releasable.

[0029] In one embodiment, the second membrane is adapted to move from an open position to a closed position so that gases can escape from the battery but cannot subsequently migrate back into the battery housing. Since some of these gases are highly flammable, this helps prevent thermal runaway events in certain circumstances. Thus, the second membrane is reversible. Automatic movement from the open position to the closed position occurs up to a certain temperature.

[0030] The present invention also relates to a battery system including a battery housing having a vent and a vent device, wherein the vent device (more specifically, a housing thereof) is inserted into the vent. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Specific embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0032] Figure 1 is a schematic perspective view of a battery system with a venting device according to the present invention;

[0033] Figure 2 is based on Figure 1 An exploded perspective view of a ventilation device according to a first embodiment;

[0034] Figure 3 yes Figure 2 A sectional side view of the ventilation device in an installed state;

[0035] Figure 4 shows a perspective view of a ventilator according to a second embodiment of the present invention;

[0036] Figure 5 Shows Figure 4 A cross-sectional side view of a ventilation device;

[0037] Figure 6 Shows Figure 4 An exploded perspective view of a ventilation device;

[0038] Figure 7 A perspective view showing a ventilator according to a third embodiment of the present invention;

[0039] Figure 8 Shows Figure 7 A cross-sectional side view of a venting device without its housing;

[0040] Fig. 9 Shows Figure 7 An exploded perspective view of a ventilation device. DETAILED DESCRIPTION

[0041] The same reference numbers in different drawings identify the same or similar elements.

[0042] Figure 1 A schematic perspective view of a battery system 10 with a ventilation device 12 is shown. Figure 1 The shape and arrangement of the battery system 10 are for illustrative purposes. The battery system 10 includes a housing 14. In the context of the present application, the battery system 10 should be understood as one of a battery submodule, a battery module, and a battery pack. Therefore, the battery housing 14 should be understood as a housing of one of a battery submodule, a battery module, and a battery system. The housing 14 can be composed of a metal alloy and / or a plastic material. The battery system 10 can include a plurality of attachment portions 16 for mounting the battery system to a fixed structure, such as an electric vehicle. The housing 14 includes a vent 18. More specifically, the housing can include 2 or 3 vents. It will eventually be understood that more than 3 vents can also be provided.

[0043] The vent 18 is adapted to receive the vent device 12 , 12 ′, 12 ″. The vent device 12 , 12 ′, 12 ″ may be connected to the vent 18 using a bayonet mount.

[0044] Figure 2 and Figure 3 A first embodiment of the vent device 12 is shown. The vent device 12 may be configured to be attached to the housing 14 for covering and / or overlapping the vent opening. Alternatively, the vent device 12 may be configured to be inserted into the vent opening 18.

[0045] like Figure 2 As shown, the venting device 12 includes a housing 20, a cap 22, a first membrane 24, and a second membrane 26. The cap 22 includes a first section connected to the first membrane 24 and a second section connected to the second membrane 26.

[0046] When the vent device 12 is configured to be inserted into the vent 18, the housing 20 of the vent device 12 cooperates with the vent 18. The housing 20 is, for example, generally annular about the longitudinal axis. However, alternatively, the shape of the housing 20 can be rectangular or oval. In fact, the shape of the housing 20 is complementary to the shape of the vent 18. The housing 20, for example, includes a first flange 28 defining a central opening 30 (see, for example, Figure 3) and a second flange 32 extending radially outward from the first flange 28. A housing bend (housing elbow) 34 is arranged between the first flange 28 and the second flange 32 and connects the first flange 28 and the second flange 32. The second flange 32 can have a substantially flat surface, wherein the first flange 28 can be inclined. The first flange 28 has, for example, a reduced diameter relative to the second flange. The first flange 28 can be provided with a first flange opening 36. The housing 20 is adapted to cooperate with the cap 22 in the installed state of the ventilator 12.

[0047] The cap 22 is, for example, a protective cover. The cap 22 includes an outer surface 38 and an inner surface 40. The inner surface 38 faces the housing 20, wherein the outer surface 38 is opposite to the inner surface 36. The cap 22 has a generally circular shape. The cap has a first portion 42 forming a central portion and a second portion 44 arranged around the first portion. The cap 22 is, for example, integral. The first portion 42 includes an edge 46 extending longitudinally from the inner surface 40, thereby defining a cavity 48. For example, the edge 46 defines a cavity 48 having a circular cross-section. The bottom 50 of the cavity 48 includes at least one vent 52, for example, a plurality of vents 52. The support structure 54 can extend between the edges 46, thereby defining a plurality of sub-cavities, and making the cap 22 more rigid. The second portion 44 of the cap is an outer annular portion. The edge 46 is connected to the second portion 44 by a cap bend 56 (cap bend) so that a groove 58 is formed at the outer surface 38 of the cap 22, and the groove 58 separates the first portion 42 from the second portion 44. The second portion 44 may include a plurality of openings 60 that are regularly distributed, for example, a plurality of openings 60 that are regularly distributed around the longitudinal axis X. The cap 22 also includes a rim 62 extending from the inner surface 40 at its periphery. The rim 62 is adapted to at least partially cover the periphery of the housing 20. More specifically, as shown in FIG. Figure 3 As shown, the rim 62 can cover the second flange 32 of the housing in the longitudinal direction. The cap portion substantially covers the housing or extends over the housing to protect the housing.

[0048] The first film 24 is a gas-permeable film. The first film 24 is made of, for example, polyethylene terephthalate (PET) or polytetrafluoroethylene (PTFE) material. The first film 24 has a disc shape.

[0049] The second film 26 has a ring shape. The second film is made of, for example, elastomer or thermoplastic elastomer.

[0050] The first film 24 is connected to the first part 42 of the cap 22. The first part 42 forms a first section. More specifically, the first film 24 is ultrasonically welded to the cap 22 in an airtight manner. For example, the first film 24 is welded to the edge 46 of the cap 22 so that the first film covers the cavity 48 (or all sub-cavities). The edge 46 includes an edge surface that is substantially parallel to the inner surface 40 of the cap, and the first film 24 is welded to the edge surface. Therefore, the distance between the first film 24 and the vent 52 is non-zero and faces the vent 52. The diameter of the first film 24 substantially corresponds to the diameter of the edge 46 that defines the cavity 48. Therefore, the first film 24 completely covers the cavity 48. As described above, the support structure 54 can be arranged in the cavity. The support structure 54 can also support the first film 24. Finally, the first film 24 can be welded to the support structure 54.

[0051] The second membrane 26 is connected to the second portion 44 of the cap. The second portion forms a second section. The second membrane 26 has an annular shape so that in the installed state of the venting device 12, the second membrane surrounds the edge 46. More specifically, the surface defining the inner circle of the annular second membrane faces the edge 46 and is arranged below the cap curved portion 56. The second membrane is press-fitted between the cap 22 and the housing 20. More specifically, the cap curved portion 56 includes a cap edge 64, and the first flange 28 of the housing includes a housing edge 66, which faces the cap edge 64 in the installed state of the venting device. The second membrane 26 is press-fitted between the cap edge 64 and the housing edge 66. For example, a section of the second membrane near the inner circle of the annular second membrane is press-fitted between the cap edge 64 and the housing edge 66. The outer periphery 68 of the second membrane forms a free end so that the second membrane 26 (more specifically, a section near the free end) can move freely relative to the cap and the housing. The free end or periphery 68 can be moved between a rest or closed position and an open position, for example to ensure emergency ventilation in the event of a technical defect in the battery system 10, in which the free end or periphery 68 rests on the surface of the housing 20. The periphery 68 rests on the first flange 28. More specifically, the periphery 68 rests on the curved portion of the first flange. In other words, the first flange 68 includes a protrusion having a specific radius of curvature, and the periphery of the second membrane contacts and rests on the protrusion. The second membrane can have a low roughness surface. More specifically, the average roughness depth Rz is important. The average roughness depth Rz is defined by the average value of the roughness depths of five consecutive individual measurement portions in the roughness profile. The surface of the second membrane has a porosity of, for example, less than 0.6 microns, particularly less than 0.4 microns. The low roughness (or porosity) of the surface allows improving the performance of the second membrane, in particular reducing the amount of moisture that passes through the membrane when the second membrane is in the closed position.

[0052] The second membrane 26 faces, for example, the first flange opening 36. The movable portion of the second membrane faces the second portion 44 of the cap, more specifically, can at least partially face a plurality of second portion openings 60. The periphery 68 of the second membrane is closer to the first membrane than the inner periphery of the second membrane. In other words, the second membrane is not flat, but forms a slope or curved shape, and when measured according to the longitudinal axis, the periphery of the second membrane is closer to the outer 38 of the cap than its inner periphery. From the upper side of the vent (or from the outer side of the cap) observed, the second membrane 26 can have a concave shape. When the second membrane is in a closed position, the shape of the second membrane allows to reduce the amount of moisture passing through the membrane.

[0053] When a certain temperature is reached, the second film can automatically move from the open position to the closed position so that the gas can escape from the battery, but cannot subsequently migrate back into the battery housing. In other words, in order to allow the gas from the battery housing or the inside of the battery housing to be discharged to the outside, the second film can be moved from the closed position (wherein the free end of the second film does not contact the housing 20) to the open position (then the free end is away from the housing 20, allowing the gas to be discharged from the inside of the battery housing to the outside). Then, after releasing the gas, when the pressure inside the battery housing is reduced to below a certain value, the second film can automatically return to its closed position. Since some of these gases are highly flammable, this helps to prevent thermal runaway events in some cases. Therefore, the second film is reversible. The second film 26 forms a diaphragm that is fixed on only one side and driven by fluid pressure. The second film opens under excess pressure (surplus pressure) inside the battery housing and closes when the excess pressure disappears.

[0054] The venting device 12, particularly when configured to be inserted into the venting port 18, further includes a sealing ring 70 extending around the housing 20. For example, the housing 20 includes a recess 72 on its outer side surface suitable for accommodating the sealing ring 70. The sealing ring 70 is made of an elastomer or a thermoplastic elastomer, for example. The sealing ring 70 is, for example, an O-ring. The sealing ring 70 is arranged below the second flange. The sealing ring has a flat surface 74 that is substantially parallel to the second flange, and a side surface 76 that is orthogonal to the flat surface. The sealing ring 70 allows the venting device 12 to be connected to the housing 14 in an airtight and watertight manner. The venting port 16 has a shape that complements the shape of the housing 20 with the sealing ring 70.

[0055] In the installed state of the ventilator 12, the cap 22 cooperates with the housing 20, for example by a snap-fit ​​connection. Figure 3As shown, the inner surface of the rim 62 is snap-fitted with a portion of the housing 20. More specifically, the rim is snap-fitted with the side surface of the second flange 32 of the housing 20. In other embodiments, the cap and the housing can be press-fitted or glued or welded. As described above, the second membrane 26 is sandwiched between the cap 22 and the housing 20, wherein the first membrane 24 is only fixed to the cap. The inner diameter of the second membrane 26 is greater than the diameter of the first membrane 24.

[0056] The cap 22, the shell 20, the first membrane 24 and the second membrane 24 are installed together to thereby form the ventilation device 12. For example, all of these components have a substantially circular shape, and their central axes (corresponding to the longitudinal axis X) coincide in the installed state of the ventilation device. The ventilation device 12 is installed in the vent of the battery system so that the first membrane faces the inside of the shell and the outer surface of the cap extends to the outside. The second membrane is arranged between the cap and the shell, and is moved to the open position in case emergency exhaust is required due to a technical defect. Figure 3 As shown, the first membrane may be generally below the housing, with the second membrane being arranged between the housing and the cap.

[0057] Figure 4 , Figure 5 and Figure 6 A second embodiment of a ventilation device 12' according to the present invention is shown. As described in more detail below, Figure 2 and Figure 3 The first embodiment disclosed in Figures 4 to 6 The main difference between the second embodiment shown in FIG. 1 and FIG. 2 is the size and position of the first membrane 24'. The first membrane 24 in the first embodiment is disposed on the bottom side of the cap, while the first membrane 24' in the second embodiment is disposed on the upper side or outer surface 38' of the cap, so that the surface of the first membrane can be increased without increasing the size of the ventilator. By increasing the surface area of ​​the first membrane 24', the air flow rate can also be increased, thereby improving the performance of the ventilator.

[0058] like Figures 4 to 6 As shown, the breather device 12 ′ includes a housing 20 ′, a cap 22 ′, a first membrane 24 ′, and a second membrane 26 ′. The breather device 12 ′ also includes a cover 78 .

[0059] The housing 20' of the venting device 12' is adapted to cooperate with the vent 18. The housing 20' is, for example, substantially annular around the longitudinal axis. However, alternatively, the shape of the housing 20' may be rectangular or elliptical. In fact, the shape of the housing 20' is complementary to the shape of the vent 18. The housing 20' is, for example, similar to the housing 20 of the first embodiment. The housing 20' comprises a first flange 28' defining a central opening 30' and a second flange 32' extending radially outward from the first flange 28'. A housing bend (housing bend) 34' is arranged between the first flange 28' and the second flange 32' and connects the first flange 28' and the second flange 32'. The second flange 32' may have a substantially flat surface, wherein the first flange 28' may be inclined. The first flange 28' has, for example, a reduced diameter relative to the second flange 32'. The first flange 28' may be provided with a first flange opening 36'. The housing 20 ′ is adapted to cooperate with the cap 22 ′ in the installed state of the breather device 12 ′.

[0060] The cap 22' includes an outer surface 38' and an inner surface 40'. The inner surface 38' faces the shell 20', wherein the outer surface 38' is opposite to the inner surface 36'. The cap 22' has a generally circular shape. The cap 22' has a first portion forming a central portion and a second portion arranged around the first portion. The cap 22' is, for example, integral. The first portion may include an edge 46' extending longitudinally from the inner surface 40, thereby defining a cavity 48. For example, the edge 46' may define a cavity having a circular cross-section. The cap 22' includes a plurality of vents 52. The vents are, for example, arranged on the first portion. The second portion of the cap 22' is an outer annular portion. The second portion may include a plurality of regularly distributed openings, such as a plurality of regularly distributed openings around the longitudinal axis X. Alternatively, the openings may be irregularly distributed. The cap 22' also includes a rim 62' extending from the inner surface at its periphery. The rim 62' is adapted to at least partially cover the periphery of the shell 20'. More specifically, as Figure 5 As shown, the rim 62' can cover the second flange 32' of the housing in the longitudinal direction. The cap portion substantially covers the housing or extends over the housing to protect the housing.

[0061] Between the rim 62' and the second portion, a slot or notch 80 may be provided to cooperate with a tongue or latch 82 provided on the cover 78. The cover 78 is mated to the cap 22' by a snap-fit ​​connection. Alternatively, the cover may be glued or welded or press-fitted to the cap 22'. The cover 78 includes a plurality of holes for allowing air to flow through the first membrane 24'. The plurality of holes are arranged, for example, in the middle of the cover 78, such as Figure 4As shown. However, alternatively, the plurality of holes may be distributed over the entire surface of the cover 78. In another alternative embodiment, the cover may be made of a porous material. In the event of overpressure, the cover may be automatically released from the cap or popped out. The snap-fit ​​connection between the cover 78 and the cap 22' makes the cover releasable in the event of overpressure. The snap-fit ​​may be sized so that the cover is released at a predetermined pressure. The cover may be made of a plastic or metal material. Similarly, the housing and / or the cap may be made of a plastic material or a metal material.

[0062] The first membrane 24' is connected to the first section of the cap. More specifically, the first membrane 24' is arranged between the cover and the cap. More specifically, the first membrane 24' can be fixed to the cap by ultrasonic welding, or the first membrane 24' can be fixed to the cap 22' by a press-fit connection between the cap 22' and the cover 78. The first membrane extends on the upper side of the cap 22'. The first membrane extends on the outer 38' of the cap. The first membrane 24' extends over the entire surface area of ​​the central part and the outer annular part. The upper side of the cap 224 is the surface opposite to the lower side of the cap 22'. The lower side of the cap 22' is suitable for facing the vent. More specifically, the first membrane 24' can extend to the rim 62', or substantially to the rim 62'. The rim 62' forms a recess in which the first membrane 24' is arranged. The recess 80 remains free to be connected to the cover 78. Therefore, the first membrane 24' faces the vent. The first membrane 24' may also face a plurality of openings 60', which may be used as vents. The diameter of the first membrane 24' substantially corresponds to the diameter of the second portion 44'. The first membrane 24' is a breathable membrane. The first membrane 24' is made, for example, of polyethylene terephthalate (PET) or polytetrafluoroethylene (PTFE) material. The first membrane 24 has a disc shape.

[0063] The cap 22' cooperates with the housing 20', for example by a snap-fit ​​connection. The cap 22' extends completely over the housing to thereby protect the housing. In other words, the cap covers the housing. For example, Figure 5 As shown, the inner surface of the rim 62' is snap-fitted with a portion of the housing 20'. More specifically, the rim is snap-fitted with the side surface of the second flange 32' of the housing 20'. In other embodiments, the cap and the housing can be press-fitted or glued or welded.

[0064] The second membrane 26' has an annular shape. The second membrane is made of, for example, an elastomer or a thermoplastic elastomer. The second membrane 26' is connected to a second section formed by the second part of the cap. The second membrane 26' has an annular shape so that in the installed state of the ventilation device 12', the second membrane surrounds the edge 46'. More specifically, the surface defining the inner circle of the annular second membrane faces the edge 46'. The second membrane is press-fitted between the edge of the cap 22' and the shell 20'. Therefore, the second membrane 26' is fixed to the cap 22'. For example, a section of the second membrane near the inner circle of the annular second membrane is press-fitted between the edge of the cap 22' and the edge of the shell 20'. The outer periphery 68' of the second membrane forms a free end so that the second membrane 26' (more specifically, the section near the free end) can move freely relative to the cap and the shell. The free end or periphery 68' can be moved between a resting position and an open position, for example to ensure emergency ventilation in the event of a technical defect in the battery system 10, in which the free end or periphery 68' rests on the surface of the housing 20. The periphery 68' rests on the first flange 28'. The second membrane 26' faces, for example, the first flange opening 36'. The movable portion of the second membrane faces the second portion of the cap, more specifically, it can at least partially face a plurality of second portion openings. The periphery 68' of the second membrane is closer to the first membrane than the inner periphery of the second membrane. In other words, the second membrane is not flat, but forms a slope or curved shape, and when measured according to the longitudinal axis, the periphery of the second membrane is closer to the outer 38' of the cap than its inner periphery. Observed from the upper side of the venting device (or from the outer side), the second membrane can have a concave shape. This arrangement allows better emergency ventilation. The second membrane can have a surface with low roughness. More specifically, the average roughness depth Rz is important. The average roughness depth Rz is defined by the average of the individual roughness depths of five consecutive individually measured portions of the roughness profile. The surface of the second membrane has a porosity of, for example, less than 0.6 micrometers, in particular less than 0.4 micrometers. The low roughness (or porosity) of the surface allows improving the performance of the second membrane, in particular reducing the amount of moisture that passes through the membrane when the second membrane is in a closed position.

[0065] The first film 24' extends completely over the second film. In other words, the first film covers the second film.

[0066] The venting device 12' may include a sealing ring 70' extending around the housing 20'. For example, the housing 20' includes a recess 72' on its outer side surface that is suitable for accommodating the sealing ring 70'. The sealing ring 70' is made of, for example, an elastomer or a thermoplastic elastomer. The sealing ring 70' is, for example, an O-ring. The sealing ring 70' is arranged below the second flange 32'. The sealing ring has a flat surface 74 that is substantially parallel to the second flange, and a side surface 76 that is orthogonal to the flat surface. The sealing ring 70' allows the venting device 12' to be connected to the housing 14' in an airtight and watertight manner.

[0067] The cap 22', the housing 20', the first membrane 22', the second membrane 24' and the cover 78 are mounted together to thereby form the breather 12'. For example, all these components have a substantially circular shape and their central axes (corresponding to the longitudinal axis X) coincide in the mounted state of the breather.

[0068] Figures 7 to 9 A ventilation device 12" according to a third embodiment is shown. The ventilation device 12" includes a shell 20", a cap 22", a first membrane 24", a second membrane 26", and a cover 78', which are arranged in a manner similar to or the same as the shell 20', the cap 22', the first membrane 24', the second membrane 26' and the cover 78 of the second embodiment. The ventilation device 12" also includes a sensor 84. The sensor 84 can be a gas sensor, a humidity sensor, a pressure sensor, a temperature sensor, etc., for example, for predictive diagnosis and predictive maintenance.

[0069] like Figure 7 , Figure 8 and Fig. 9 As shown, the sensor can be disposed within the cavity formed by the cap portion 22". More specifically, the sensor 84 can be disposed within the cavity 48" defined by the edge 46" of the first portion 42". More generally, the sensor 84 is disposed within the ventilation device so that the sensor can collect the desired data. In the case of the gas sensor 84, the presence of the sensor in the cavity allows the sensor to be present in the main airflow path. In addition, as shown in FIG. Figure 7 and Figure 8 As shown, the sensor does not protrude from the rest of the breather device (in particular not from the housing and the cap). Thus, the breather device 12" remains compact. The sensor arranged in the cavity formed by the cap is protected by the walls of the cavity. This reduces the risk of damage.

[0070] When in the installed state, the venting device is compact and allows to realize two functions required in the battery system (pressure balance in the normal working environment and emergency ventilation in the case of technical defects). These two functions are realized with only a few elements, that is, only the cap 22, the housing 20, the first membrane 24 and the second membrane 26 (and the last sealing ring 70). No more elements are required. In addition, the arrangement of the first membrane 24 relative to the second membrane 26 allows to realize a compact device. The position and shape of the second membrane (concave shape when viewed from the upper side) also allow to reduce the overall size of the venting device. In addition, the second membrane reduces the penetration of moisture in the shell. The venting device is also particularly flat so that it does not protrude in a non-functional or non-homogeneous manner. In a normal working environment, the first membrane balances the pressure between the inside of the shell and the external environment. The vents allow for conventional and easy ventilation, and their location-away from the first membrane-reduces the risk of moisture entering the shell. For example, in the case of emergency exhaust, the second membrane opens at an internal pressure between 0.05 bar and 0.15 bar.

[0071] Reference Numbers

[0072] Battery System 10

[0073] Ventilation device 12, 12', 12"

[0074] Housing 14

[0075] Attachment section 16

[0076] Vent 18

[0077] Shell 20, 20', 20"

[0078] Cap 22, 22', 22"

[0079] First film 24, 24', 24"

[0080] The second film 26, 26',

[0081] First flange 28, 28'

[0082] Center opening 30, 30'

[0083] Second flanges 32, 32'

[0084] Shell curved parts 34, 34'

[0085] First flange openings 36, 36'

[0086] Outer surface 38, 38'

[0087] Inner surface 40, 40'

[0088] Part 142

[0089] Part 24

[0090] Edge 46

[0091] Cavity 48

[0092] Bottom 50

[0093] Ventilation hole 52

[0094] Support structure 54

[0095] Cap bent portion 56

[0096] Groove 58

[0097] The opening 60 of the second part

[0098] Rim 62

[0099] Cap edge 64

[0100] Shell edge 66

[0101] Perimeter 68

[0102] Sealing ring 70

[0103] Recess 72

[0104] Flat surface 74

[0105] Side surface 76

[0106] Cover 78

[0107] Slot or notch 80

[0108] Tongue or latch 82

[0109] Sensor 84

Claims

1. A venting device (12, 12', 12") for a battery system (10), the battery system having a battery housing (14), the battery housing having a vent (18), the venting device comprising: - a housing (20, 20', 20") adapted to be connected to said battery housing (14), a cap (22, 22', 22") having an outer surface (38, 38', 38") and an inner surface (40, 40', 40"), wherein the inner surface (40, 40', 40") faces the housing (20, 20', 20"), and wherein the cap (22, 22', 22") cooperates with the housing (20, 20', 20") and extends above the housing, a first membrane (24, 24', 24") adapted to ensure pressure balance between the interior of the housing (14) and its environment under normal operating conditions of the battery system, a second membrane (26, 26', 26") adapted to ensure emergency ventilation in the event of a technical defect in the battery system (10), It is characterized in that the cap (22, 22', 22") comprises a first section connected to the first membrane (24, 24', 24") and a second section connected to the second membrane (26, 26', 26").

2. The ventilation device (12, 12', 12") according to claim 1, wherein: The first film (24, 24', 24") is a breathable film.

3. The ventilation device (12, 12', 12") according to claim 1 or 2, wherein: The second membrane (26, 26', 26") is press-fitted between the housing (20, 20', 20") and the cap (22, 22', 22"), and wherein the second membrane comprises an annular shape having an inner periphery and an outer periphery, and the outer periphery is closer to the cap than the inner periphery.

4. The ventilation device (12, 12', 12") according to any one of the preceding claims, wherein The cap (22, 22', 22") is generally circular, having a central portion (42, 42') adapted to be covered by the first membrane (24, 24', 24") and an outer annular portion (44, 44') adapted to be partially covered by the second membrane.

5. The ventilation device (12, 12', 12") according to claim 4, wherein: The central portion (42) includes a plurality of vent holes (52, 52').

6. The ventilation device (12, 12', 12") according to claim 4 or 5, wherein: The outer annular portion (44) includes a plurality of regularly distributed openings (60).

7. The ventilation device (12', 12") according to any one of claims 4 to 6, wherein: The first film covers the central portion (42') and the outer annular portion (44').

8. The ventilation device (12, 12', 12") according to any one of claims 4 to 7, wherein: The cap portion (22, 22', 22") includes a rim (62).

9. The ventilation device (12, 12', 12") according to any one of claims 4 to 8, wherein: The central portion (42) includes an edge (46) extending longitudinally from the inner surface along the longitudinal axis (X), wherein the edge (46) defines one or more cavities.

10. The breather device (12, 12', 12") according to any one of the preceding claims, further comprising a sealing ring (70) extending around the housing (20).

11. The ventilation device (12, 12', 12") according to any one of the preceding claims, wherein The second membrane (26) is annular, and wherein the first membrane (24) is arranged substantially in the center of the second membrane (26).

12. The ventilation device (12, 12', 12") according to any one of the preceding claims, wherein The first film (24) is made of polyethylene terephthalate (PET) or polytetrafluoroethylene (PTFE) material.

13. The ventilation device (12, 12', 12") according to any one of the preceding claims, wherein The second film (26) is made of elastomer or thermoplastic elastomer.

14. The ventilation device (12, 12', 12") according to any one of the preceding claims, wherein A sensor is arranged in the cavity of the ventilation device, wherein the sensor is a gas sensor, a humidity sensor, a pressure sensor and / or a temperature sensor.

15. A battery system (10) comprising a battery housing having a vent (18) and a vent device (12, 12', 12") according to any one of the preceding claims, wherein: The housing (20) is inserted into the vent (18).

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