Battery ventilation valve with thermal activation element

Abstract

A battery ventilation valve for a battery housing comprises a valve body defining an interior cavity disposed about a normal axis and extending between a first opening at a first end of the valve body and a second opening at a second end of the valve body. A piston is moveably disposed in the interior cavity between an open position that allows flow of gas into and out of the battery housing and a closed position that prevents flow of gas into and out of the battery housing. A biasing element that biases the piston along the normal axis and a thermal activation element having an activation temperature are also disposed in the interior cavity. The thermal activation element transforms from an inactivated state to an activated state at the activation temperature to overcome the biasing element and move the piston from the open position into the closed position.

Description

BATTERY VENTILATION VALVE WITH THERMAL ACTIVATION ELEMENTCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application 63 / 530,364, filed August 2, 2023, the disclosure of which is incorporated by reference in its entirety.FIELD OF THE DISCLOSURE

[0002] The present disclosure relates to a valve for a battery housing.BACKGROUND

[0003] Batteries for electric vehicles (EVs) are typically enclosed in a battery housing and located on the underside of the vehicle. Electric vehicle (EV) battery housings protect a plurality of battery cells within the housing from exposure to water, dust, debris, and other elements as well as harsh external conditions. Collectively, the plurality of battery cells and the housing can be referred to as a battery pack.

[0004] To start, EV battery packs face challenges due to their location, size, and chemical makeup. Because EV battery packs are located on the undersides of vehicles, they can be exposed to water fording or submersion on the roadway. Of course, roadway water often includes salt and other corrosive chemicals. Further, car washes can expose vehicles to high-pressure sprays of varying temperature. Dust, debris, and vibration can also impact the battery pack. So, on one hand, EV battery packs must provide a barrier to harsh external conditions experienced by EV’s.

[0005] On the other hand, as is explained below, EV battery packs must be vented. To start, the size of battery packs presents challenges. Battery packs can weigh up to a ton and often contain hundreds of cells including large air volumes that can exertforces on the enclosures as pressures increase. As such, EV battery packs must be vented to account for differential pressure due to altitude or temperature change.

[0006] That said, the biggest concern with battery packs is the potential for thermal runaway. If lithium-ion battery cells are damaged by puncturing, overcharging, manufacturing defect or other causes, they can release gas and heat. Various venting strategies including dual stage venting and various combinations of vents selectively located on the battery pack can be employed in an effort to control or moderate thermal runaway. Traditional thermal runaway control strategies have utilized dual stage battery vents that open. However, newer thermal runaway control strategies may involve closing certain battery vents and opening other battery vents during thermal runaway.

[0007] Considering the challenges above and the evolving strategies required to deal with the challenges, there remains a continued need for an improved battery ventilation valve.SUMMARY

[0008] A battery ventilation valve (“valve”) for a battery housing is disclosed. In a first example, the battery ventilation valve comprises a valve body defining an interior cavity disposed about a normal axis and extending between a first opening at a first end of the valve body and a second opening at a second end of the valve body. A piston is moveably disposed in the interior cavity between an open position that allows flow of gas into and out of the battery housing and a closed position that prevents flow of gas into and out of the battery housing. A biasing element that biases the piston along the normal axis and a thermal activation element having an activation temperature are also disposed in the interior cavity. The thermal activation element transforms from aninactivated state to an activated state at the activation temperature to overcome the biasing element and move the piston from the open position into the closed position.

[0009] In a second example, the valve comprises a valve body defining an interior cavity extending between a first opening and a second opening and disposed about a normal axis. The valve body presents a biasing surface proximal to the first opening. A valve bottom is proximal to the second opening and shaped to couple to a surface of a battery housing or the valve body. A membrane is disposed in the interior cavity. A piston is moveably disposed in the interior cavity. The piston is movable between an open position that allows flow of gas into and out of the battery housing and a closed position that prevents flow of gas into and out of the battery housing. A biasing element is disposed between the biasing surface and the piston. The biasing element biases the piston along the normal axis and into the open position. A thermal activation element having an activation temperature is disposed in the interior cavity between the valve bottom and the piston. The thermal activation element transforms from the inactivated state to the activated state at a temperature at or above the activation temperature to overcome the biasing element and move the piston along the normal axis from the open position into the closed position.

[0010] A method of hermetically sealing a battery housing with a battery ventilation valve is also disclosed. The valve comprises a valve body defining an interior cavity, a piston moveably disposed in the interior cavity, and a thermal activation element having an activation temperature. The method includes the steps of: heating the thermal activation element; transforming the thermal activation element from a first shape to a second shape; and moving the piston from an open position, which allows flow of gas into and out of the battery housing, to a closed position to prevent flow of gas into and out of the battery housing.

[0011] These and other features of the disclosure will be more fully understood and appreciated by reference to the description of the examples and the drawings.

[0012] Before the examples of the disclosure are explained in detail, it is to be understood that the disclosure is not limited to the details of operation or to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The disclosure may be implemented in various other examples and of being practiced or being conducted in alternative ways not expressly disclosed herein. In addition, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use of “including” and “comprising” and variations thereof is meant to encompass the items listed thereafter and equivalents thereof as well as additional items and equivalents thereof. Further, enumeration may be used in the description of various examples. Unless otherwise expressly stated, the use of enumeration should not be construed as limiting the disclosure to any specific order or number of components. Nor should the use of enumeration be construed as excluding from the scope of the disclosure any additional steps or components that might be combined with or into the enumerated steps or components.BRIEF DESCRIPTION OF THE DRAWINGS|0013 | Figure 1 is a perspective view of an embodiment of the battery ventilation valve disclosed herein.

[0014] Figure 2 is an exploded view of the battery ventilation valve of Figure 1.

[0015] Figure 3 is a cross-sectional view of the battery ventilation valve of Figure1 in an open position.

[0016] Figure 4 is a cross-sectional view of the battery ventilation valve of Figure1 in a closed position.

[0017] Figure 5 is a cross-sectional view of the battery ventilation valve of Figure 1 including a thermal activation element comprising a spring formed with a shape memory alloy.

[0018] Figure 6 is an alternative embodiment of the battery ventilation valve of Figure 1 including a thermal activation element comprising wax.

[0019] Figure 7 is a perspective view of the battery ventilation valve of Figure 1 prior to engagement with an orifice in an exterior surface of a battery housing.

[0020] Figure 8 is a bottom perspective view of the battery ventilation valve of Figure 7 having a plurality of engagement tabs received in a corresponding plurality of notches in the exterior surface of the battery housing.

[0021] Figure 9 is a bottom view of the battery ventilation valve of Figure 8 having a plurality of engagement tabs received in a corresponding plurality of notches in the exterior surface of the battery housing.

[0022] Figure 10 is a bottom perspective view of the battery ventilation valve of Figure 9 wherein the plurality of engagement tabs are rotationally engaged with the corresponding plurality of notches in the exterior surface of the battery housing to secure the battery ventilation valve to the battery housing.

[0023] Figure 11 is an enlarged view of one of the plurality of engagement tabs of the battery ventilation valve of Figure 10 rotationally engaged with one of the corresponding plurality of notches in the exterior surface of the battery housing.

[0024] Figure 12 is a perspective view of another embodiment of the battery ventilation valve disclosed herein.

[0025] Figure 13 is an exploded view of the battery ventilation valve of Figure12.

[0026] Figure 14 is a cross-sectional view of the battery ventilation valve ofFigure 12 in an open position.

[0027] Figure 15 is a cross-sectional view of the battery ventilation valve ofFigure 12 in a closed position.

[0028] Figure 16 is a cross-sectional view of the battery ventilation valve ofFigure 12 including a thermal activation element comprising a spring formed with a shape memory alloy.

[0029] Figure 17 is an alternative embodiment of the battery ventilation valve of Figure 12 including a thermal activation element comprising wax.

[0030] Figure 18 is a top perspective view of the battery ventilation valve of Figure 12 prior to engagement with an orifice in an exterior surface of a battery housing.

[0031] Figure 19 is a side perspective view of the battery ventilation valve of Figure 18 having a plurality of locking tabs received in a corresponding plurality of apertures in the exterior surface of the battery housing.

[0032] Figure 20 is a bottom perspective view of the battery ventilation valve of Figure 19 wherein the plurality of locking tabs are rotationally engaged with the corresponding plurality of apertures in the exterior surface of the battery housing to secure the battery ventilation valve to the battery housing.

[0033] Figure 21 is an enlarged view of one of the plurality of locking tabs of the battery ventilation valve of Figure 20 rotationally engaged with one of the corresponding plurality of apertures in the exterior surface of the battery housing.

[0034] Figure 22 is a perspective view of another embodiment of the battery ventilation valve disclosed herein including a cartridge and a header.

[0035] Figure 23 is an isolated view of the cartridge of the embodiment of the battery ventilation valve of Figure 22.

[0036] Figure 24 is an exploded view of the cartridge of the embodiment of the battery ventilation valve of Figure 22.

[0037] Figure 25 is a flow chart describing a method of hermetically sealing a battery housing with a battery ventilation valve.DETAILED DESCRIPTION

[0038] A battery ventilation valve is provided. While discussed herein in connection with an electric vehicle (“EV”) battery pack, the subject battery ventilation valve is suitable for a wide range of applications wherein temperature-based opening and / or closing of a valve is beneficial or required and not limited to battery packs or automotive applications. Referring to Figures 1-23, wherein like numerals indicate corresponding parts throughout the several views, the battery ventilation valve (“valve”) is illustrated and generally designated at 10. The valve 10 allows the movement of gas in and out of a battery housing 12 for a battery pack while preventing in and out movement of liquid (e.g., water) and particulate contaminants and providing pressure equalization.

[0039] The valve 10 comprises a valve body 14 defining an interior cavity 20 disposed about a normal axis AN and extending between a first opening 16 at a first end 32 of the valve body 14 and a second opening 18 at a second end 34 of the valve body 14. A piston 22 is moveably disposed in the interior cavity 20 between an open position that allows flow of gas into and out of the battery housing 12 and a closed position that prevents flow of gas into and out of the battery housing 12. A biasing element 46 that biases the piston 22 along the normal axis AN and a thermal activation element 26 having an activation temperature are also disposed in the interior cavity 20. The thermal activation element 26 transforms from an inactivated state to an activated state at theactivation temperature to overcome the biasing element 46 and move the piston 22 from the open position into the closed position.

[0040] Referring now to the embodiment of Figures 1-11, the valve 10 comprises the valve body 14 having an exterior surface 28 and an interior surface 30 defining the interior cavity 20. As described previously, the interior cavity 20 is disposed about the normal axis AN and extends between the first opening 16 at the first end 32 of the valve body 14 and the second opening 18 at the second end 34 of the valve body 14. A membrane 36 may also be disposed in the interior cavity 20. A piston 22 is movably disposed in the interior cavity 20 and movable between the open position and the closed position. A valve bottom 24 may also be disposed in the second opening 18. The biasing element 46 that biases the piston 22 along the normal axis AN and the thermal activation element 26 having an activation temperature are also disposed in the interior cavity 20. Each of the different components that may be included in this embodiment of the valve 10 are clearly distinguished in the exploded view of Figure 2.

[0041] In this embodiment, the thermal activation element 26 having an activation temperature is disposed in the interior cavity 20 between the valve bottom 24 and the piston 22. The valve body 14 presents a biasing surface 42 proximal to the first opening 16. In turn, the piston 22 has a first and a second surface 38, 40. The first surface 38 of the piston 22 is shaped to (1) contact the valve body 14 to create a pneumatic seal when the piston 22 is in the closed position and (2) provide the biasing surface 42 upon which to receive a biasing element 46. The valve 10 includes the biasing element 46 to counter-bias the valve 10 and the thermal activation element 26. The biasing element 46 is disposed between the biasing surface 42 defined by the interior surface 30 of the valve body 14 and located at the first end 32 of the valve body 14 and the piston 22. More specifically, in this embodiment, the biasing element 46 isdisposed between the biasing surface 42 located at the first end of the valve body 14 and an engagement track 48 defined by the first surface 38 of the piston 22. As such, the biasing element 46 biases the piston 22 along the normal axis AN towards the second end 34 of the valve body 14 (towards a surface of the battery housing 12) and into the open position. Further, the valve bottom 24 is proximal to the second opening 18 and shaped to couple to a surface of a battery housing 12. The thermal activation element 26 is disposed between the valve bottom 24 and the second surface 40 of the piston 22. When the thermal activation element 26 is activated, the thermal activation element 26 changes shape to overcome the bias of the biasing element 46 and move the piston 22 along the normal axis AN from the open position into the closed position. The open and closed positions are best illustrated in Figures 3 and 4.

[0042] In Figure 3, the valve 10 is in the open position, the thermal activation element 26 is in the inactivated state. In this embodiment, the first surface 38 of the piston 22 defines a sealing channel 50 having a piston seal 52 disposed therein and the valve body 14 defines a sealing element 53 in the interior cavity 20. In Figure 3, the piston seal 52 and the sealing element 53 are separated and allow passage of gas through the interior cavity 20 as is illustrated by the arrows showing a 90° turn. The downward arrows at the first opening 16 at the first end 32 of the valve body 14 represent the flow of gas from outside the valve 10 into the interior cavity 20. The downward arrows centrally located within the interior cavity 20 represent the further flow of gas through the membrane 36 and into the battery housing 12. The upward arrows, including the arrows showing a 90° turn centrally located within the interior cavity 20 represent the gas being expelled from the battery housing 12 through the valve 10.

[0043] In Figure 4, the valve 10 is in the closed position and the thermal activation element 26 is in the activated state. In this example, the thermal activationelement 26 comprises a spring that increases in length, to overcome the bias of the biasing element 46 and push the piston seal 52 into contact with the sealing element 53. That is, the sealing element 53 is received in the sealing channel 50. In Figure 4, the piston seal 52 and the sealing element 53 are in contact and thus the valve 10 is sealed (in the closed position) to prevent passage of gas through the interior cavity 20 as is illustrated by the upward arrows that abruptly stop because the sealing element 53 is received in the sealing channel 50. The upward arrows of Figure 4 represent the gas being trapped in the battery housing 12 with the valve 10 in the closed position.

[0044] The valve 10 may include the membrane 36. The membrane 36 allows gases to flow in and out of the enclosure but helps prevent liquid and particle contaminants from entering the battery housing 12. The membrane 36 typically comprises a polymer and may be nonwoven, woven, or foamed. The polymer filters gas passing therethrough, preventing liquid and particulate contaminants from passing through the valve 10 and into the battery housing 12. As a non-limiting example, the membrane can comprise polytetrafluoroethylene (PTFE) or expanded polytetrafluoroethylene (ePTFE) membranes that prevents liquid (e.g., water) and particulate contaminants from infiltrating the battery housing 12 and provides pressure equalization.

[0045] Referring now to Figure 5, in the embodiment illustrated, the valve 10 comprises a cover 66 defining one or more flow apertures 68 to allow movement of gas in and out of the valve body 14 through the membrane 36. Further, the cover 66 is shaped to couple to the first end 32 of the valve body 14. An exterior perimeter of the cover 66 includes a plurality of attachment apertures 70 with each of the plurality of attachment apertures 70 defined in-part by a lower rail 72. Each of the plurality of attachment apertures 70 is shaped to receive one of a corresponding plurality of angledtabs 74 defined by an exterior surface of the valve body 14. Downward pressure on the cover 66 forces each lower rail to slide along each corresponding angled tab and snap into each aperture whereby contact between a bottom surface of each angled tab and each lower rail secures the cover 66 to the first end 32 of the valve body 14. The cover 66 includes a plurality of flow apertures 68, which allow gas to pass through the cover 66 and into the interior cavity 20 of the valve 10. As is also illustrated, the membrane 36 is pinched between the cover 66 and a shelf defined by the valve body 14. Further, a seal 76 is disposed between the cover 66 and the membrane 36 to ensure that all of the gas that flows in and out of the valve 10 is filtered by the membrane 36.

[0046] The thermal activation element 26 transforms from an inactivated state to an activated state when the thermal activation element 26 reaches the activation temperature. The valve 10 is open when the piston 22 is in the open position and the thermal activation element 26 is in the inactivated state and the valve 10 is closed when the piston 22 is in the closed position and the thermal activation element 26 is in the activated state. As such, when the thermal activation element 26 is in the inactivated state the valve 10 is open and the piston 22 is in an open position to allow movement of gas through the interior cavity 20 of the valve 10. Accordingly, when the thermal activation element 26 is in the activated state the valve 10 is closed and the piston 22 is in the closed position to prevent movement of gas through the interior cavity 20 of the valve 10.

[0047] The activation temperature of the thermal activation element 26 is typically a temperature of greater than about 80, or about 90 °C. The activation temperature of the thermal activation element 26 is typically a temperature of from about 80 to about 300, from about 85 to about 250, from about 90 to about 200, from about 90 to about 110, or from about 95 to about 105 °C. For example, variousembodiments of the thermal activation element 26 have an activation temperature of 90± 10, 95 ± 10, 100 ± 10, 105 ± 10, 110 ± 10, 115 ± 10, 120 ± 10, 125 ± 10, 130 ± 10, 135 ± 10, 140 ± 10, 145 ± 10, 150 ± 10, 155 ± 10, 160 ± 10, 165 ± 10, 170 ± 10, or 175 ± 10 °C. Of course, embodiments of the thermal activation element 26 having an activation temperature of any temperature between 90 and 200 °C ± 10 °C are contemplated herein. In some embodiments, the thermal activation element 26 can maintain functionality at temperatures up to about 200, 300, or 400 °C. That is, the thermal activation element 26 does not deform, melt, or degrade at temperatures up to about 200, 300, or 400 °C. Of course, in other design-dependent embodiments, the thermal activation element 26 can be designed to deform, melt, or degrade at the activation temperature. When the thermal activation element 26 transforms from an inactivated state to an activated state the thermal activation element 26 changes shape.

[0048] It should be appreciated that the change in shape of the thermal activation element 26 can be an increase in a dimension or a decrease in a dimension such as length. In one embodiment, as is illustrated in the figures, the thermal activation element 26 has a first length in the inactivated state and a second length in the activated state, wherein the second length is greater than the first length. However, in another embodiment, the thermal activation element 26 has a first length in the inactivated state and a second length in the activated state, wherein the second length is less than the first length. Of course, the thermal activation element 26 can comprise a fastener formed from a thermally activated material that releases the piston 22 from an open position to a closed position. In such an example, the thermal activation element 26 has a first, singular shape comprising in the inactivated state and a second shape comprising two or more portions.

[0049] In Figure 5, a cross-sectional view of the battery ventilation valve ofFigure 1 including a thermal activation element 26 comprising a spring formed with a shape memory alloy is illustrated, when the spring reaches the activation temperature, it transforms, in this example, becoming longer. In Figure 6, an alternative embodiment of the battery ventilation valve of Figure 3 is illustrated. In the embodiment of Figure 4, the thermal activation element 26 comprises a wax that expands when heated to a temperature at or above the activation temperature. In these examples, the piston is biased towards the surface of the battery housing 12 for a battery pack by the biasing element 46.

[0050] Referring now to Figures 7-11, the second end 34 of the valve body 14 may define an engagement surface having one or more fasteners engageable with the exterior surface of a battery housing 12. Generally speaking, the second end 34 of the valve body 14 includes one or more of a first attachment feature and a surface of the battery housing 12 includes one or more of an attachment feature which are shaped to connect via the application of force, rotation, or direct. Of course, absent fasteners, the valve 10 can be bolted, threaded, or welded to the surface of the housing about the orifice.

[0051] In this embodiment, the valve 10 includes a plurality of engagement tabs 54 and a corresponding plurality of notches 56 in the exterior surface of the battery housing 12. The corresponding plurality of notches 56 are disposed about the perimeter of the orifice in the battery housing 12. Each of the plurality of engagement tabs 54 has an engagement projection 58 at least partially defining an engagement slot 60. Each of the plurality of engagement tabs 54 is received in one of the corresponding plurality of notches 56 in the exterior surface of the battery housing 12, and rotational movement of the valve 10 moves a locking rib 62 into a corresponding locking slot 64 in theexterior surface of the battery housing 12 to engage the valve 10 and the battery housing 12.

[0052] In Figure 7, the valve 10 is positioned over / aligned with an orifice in the battery housing 12 prior to fastening. Figure 7 is essentially a perspective view of the battery ventilation valve prior to the fastening process and before engagement with the orifice in the exterior surface of a battery housing 12. In Figure 7, the downward arrow (2) represents the alignment, insertion, and contacting of the of the valve 10 with the housing prior to the view of Figures 8 and 9. In Figure 8, a bottom perspective view of the valve 10 of Figure 7 having the plurality of engagement tabs 54 received in the corresponding plurality of notches 56 in the exterior surface of the battery housing 12 is shown. Figure 9 illustrates a bottom view of the valve 10 of Figure 8 with the plurality of engagement tabs 54 received in the corresponding plurality of notches 56 in the exterior surface of the battery housing 12. In Figure 7, the semi-circular arrow represents the application of rotational force on the valve 10 such that the plurality of engagement tabs 54 are received in a corresponding plurality of notches 56 in the exterior surface of the battery housing 12 and the valve 10 is fastened to the battery housing 12. Figure 10 shows the plurality of engagement tabs 54 rotationally engaged with the corresponding plurality of notches 56 in the exterior surface of the battery housing 12 to secure the valve 10 to the battery housing 12, whereas Figure 11 shows an enlarged view of one of the plurality of engagement tabs 54 engaged with one of the corresponding plurality of notches 56 in the exterior surface of the battery housing 12. The semi-circular arrows in Figure 10 represent the previous movement of the valve 10, which engaged the valve 10 with the exterior surface of the battery housing 12.

[0053] Figures 8, 10, and 11 show an external seal 80 positioned between the valve 10 and the surface of the battery housing 12 to prevent the ingress or egress of airaround the valve 10. The external seal 80 can be positioned in a seal track 82 defined at the second end 34 of the valve body 14.

[0054] The valve 10 of Figures 1-11 can be cast and include the valve body 14 and / or the cover 66 comprising a metal such as, but not limited to, aluminum. Of course, the valve 10 of this embodiment can also be injection molded and include the valve body 14 and / or the cover 66 comprising a polymer including, but not limited to, nylon. A valve 210 of Figures 12-21, which is described immediately below, can be stamped, and include a valve body 214 comprising a metal including, but not limited to, aluminum. Of course, the valve 210 of this embodiment can also be injection molded and include the valve body 214 comprising a polymer such as, but not limited to, nylon.

[0055] Referring now to Figures 12-21, the valve 210 comprises a valve body 214 defining an interior cavity 220 disposed about a normal axis AN and extending between a first opening 216 at a first end 232 of the valve body 214 and a second opening 218 at a second end 234 of the valve body 214. A piston 222 is moveably disposed in the interior cavity 220 between an open position that allows flow of gas into and out of the battery housing 212 and a closed position that prevents flow of gas into and out of the battery housing 212. A biasing element 246 that biases the piston 222 along the normal axis AN and a thermal activation element 226 having an activation temperature are also disposed in the interior cavity 220. More specifically, in this embodiment, the biasing element 246 is disposed between the biasing surface 242 located at the first end of the valve body 214 and an engagement track defined by the first surface 238 of the piston 222. As such, the biasing element 246 biases the piston 222 along the normal axis AN towards the second end 234 of the valve body 214 (towards a surface of the battery housing 212) and into the open position. The thermal activation element 226 transforms from an inactivated state to an activated state at theactivation temperature to overcome the biasing element 246 and move the piston 222 from the open position into the closed position.

[0056] The components of the valve 210 of this embodiment are similar to those of the first embodiment with the exception being that this embodiment does not include a cover, rather the first end of the valve body includes an end wall 266 defining one or more flow apertures 268 to allow movement of gas in and out of the valve body 214 through the membrane 236. As such, a membrane mount 267, which is not required in the first embodiment, is utilized to secure the membrane 236 in place within the interior cavity 220 of the valve body 214. The membrane mount 267 is shaped to couple to a feature on an interior surface of the valve body 214 to secure the membrane 236 between at least a portion of an end wall of the membrane mount 267. Further, a seal 276 is disposed between the membrane mount 267 and the valve body 214 to ensure that the gas that flows in and out of the valve 210 is filtered by the membrane 236. The components of this embodiment of the valve 210 are clearly set forth in the exploded view of Figure 13.

[0057] As is explained above, when the thermal activation element 226 is activated, the thermal activation element 226 changes shape to overcome the bias of the biasing element 246 and move the piston 222 along the normal axis AN from the open position into the closed position. Just like in the previous embodiment, the thermal activation element 226 is disposed in the interior cavity 220 between a valve bottom 224 and the piston 222. The open and closed positions are best illustrated in Figures 14 and 15.

[0058] In Figure 14, the valve 210 is in the open position, the thermal activation element 226 is in the inactivated state. In this embodiment, a first surface, which is opposite a second surface, of the piston 222 defines a sealing channel 250 having apiston seal 252 disposed therein and the valve body 214 defines a sealing shelf 253 in the interior cavity 220. In Figure 14, the piston seal 252 and the under-surface of the sealing shelf 253 are separated and allow passage of gas through the interior cavity 220 as is illustrated by the arrows. The downward arrows at the first opening 16 at the first end 32 of the valve body 14 represent the flow of gas from outside the valve 210 into the interior cavity 220. The downward arrows (including the diagonal downward arrows) centrally located within the interior cavity 220 represent the further flow of gas through the membrane 36, between the separated piston seal 252 the sealing shelf 253, and into the battery housing 212. The upward arrows (including the diagonal downward arrows) centrally located within the interior cavity 220 represent the gas being expelled from the battery housing 212 through the valve 210.

[0059] In Figure 15, the valve 210 is in the closed position and the thermal activation element 226 is in the activated state. In this example, the thermal activation element 226 comprises a spring that increases in length, to overcome the bias of the biasing element 246 and push the piston seal 252 into contact with the sealing shelf 253. In Figure 15, the piston seal 252 and the sealing shelf 253 are in contact and thus the valve 210 is sealed (in the closed position) to prevent passage of gas through the interior cavity 220 as is illustrated by the upward arrows that abruptly stop because the sealing shelf 253 is in contact with the sealing shelf 253. The upward arrows of Figure 15 represent the gas being trapped in the battery housing 212 with the valve 210 in the closed position.

[0060] In Figure 16, a cross-sectional view of the battery ventilation valve of Figure 12 including a thermal activation element 226 comprising a spring formed with a shape memory alloy is illustrated, when the spring reaches the activation temperature, it transforms, in this example, becoming longer. In Figure 17, an alternativeembodiment of the battery ventilation valve of Figure 16 is illustrated. In the embodiment of Figure 4, the thermal activation element 226 comprises a wax that expands when heated to a temperature at or above the activation temperature. In these examples, the piston 222 is biased towards the surface of the battery housing 212 by the biasing element 246.

[0061] Referring now to Figures 18-21, the valve 210 includes one or more fasteners to engage the valve 210 and the battery housing 212. Each of the one or more fasteners are further defined as a plurality of locking tabs 254, each of the plurality of locking tabs 254 having a locking projection 258 at least partially defining a locking slot 260 and a locking tip 262 opposite the locking slot 260, wherein each of the plurality of locking tabs 254 is received in one of a corresponding plurality of slots 256 in the exterior surface of the battery housing 212 and rotational movement of the valve 210 locks the plurality of locking tabs 254 in the corresponding plurality of slots 256 to engage the valve 210 and the battery housing 212.

[0062] In Figure 18, the valve 210 is positioned over / aligned with an orifice in the battery housing 212 prior to fastening. Figure 18 is essentially a perspective view of the valve 210 prior to the fastening process and before engagement with the orifice in the exterior surface of the battery housing 212. In Figure 18, the downward arrow (2) represents the alignment, insertion, and contacting of the of the valve 210 with the battery housing 212 prior to the view of Figure 19. Figure 19 is a side perspective view of the valve 10 of Figure 18 with the plurality of locking tabs 254 received in the corresponding plurality of slots 256 in the exterior surface of the battery housing 212.

[0063] Figures 16 and 17 show an external seal 280 that is positioned between the valve 210 and the surface of the battery housing 212 to prevent the ingress or egress of air around the valve 210. The external seal 280 can be positioned in a seal trackdefined at the valve bottom 224 of the valve body 214.

[0064] In Figure 18, the semi-circular arrow (2) represents the application of rotational force on the valve 210 such that the plurality of locking tabs 254 engage the corresponding plurality of slots 256 in the exterior surface of the battery housing 212 and the valve 210 is fastened to the battery housing 212. Figure 20 is a bottom perspective view of the plurality of locking tabs 254 rotationally engaged with the corresponding plurality of slots 256 in the exterior surface of the battery housing 212 to secure the valve 210 to the battery housing 212. Figure 21 shows an enlarged view of one of the plurality of locking tabs 254 engaged with one of the corresponding plurality of slots 256 in the exterior surface of the battery housing 212 More specifically, Figure 21 shows a wall of the battery housing 212 at a first end of the slot received in a locking slot 260 and the locking tip 262 opposite the locking slot engaged with the wall of the battery housing 212 at a second end of the slot.

[0065] Referring now to Figure 22, one embodiment of the battery ventilation valve 410 comprises a header 484. The header 484 defines a header body 486 defining a header cavity 488 disposed about the normal axis AN and shaped to receive a valve body 414. Figure 23 is an isolated view of the cartridge of this embodiment of the battery ventilation valve 410. The valve components of this embodiment are like those of the previous embodiments. In this example, a cartridge comprising the valve body 414 and other components is simply received in the header cavity 488 and the header 484 is then secured to a battery housing (described herein but not illustrated in Figure 22).

[0066] Figure 24 is an exploded view of the cartridge of the embodiment of the battery ventilation valve of Figure 22. this embodiment of the battery ventilation valve 410. The battery ventilation valve 410 of this embodiment comprises a valve body 414defining an interior cavity 420 disposed about the normal axis AN and extending between a first opening 416 at a first end 432 of the valve body 414 and a second opening 418 at a second end 434 of the valve body 414. A piston 422 is moveably disposed in the interior cavity 420 between an open position that allows flow of gas into and out of the battery housing and a closed position that prevents flow of gas into and out of the battery housing. A biasing element 446 that biases the piston 422 along the normal axis AN and a thermal activation element 426 having an activation temperature are also disposed in the interior cavity 420. More specifically, in this embodiment, the biasing element 446 is disposed between the biasing surface 442 located at the first end of the valve body 414 and an engagement track 448 defined by the first surface 438 of the piston 422. As such, the biasing element 446 biases the piston 422 along the normal axis AN towards the second end 434 of the valve body 414 (towards a surface of the battery housing) and into the open position. The thermal activation element 426 transforms from an inactivated state to an activated state at the activation temperature to overcome the biasing element 446 and move the piston 422 from the open position into the closed position. Of course, this embodiment of the battery ventilation valve 410 includes a membrane 436 as described above. As is also explained above, when the thermal activation element 426 is activated, the thermal activation element 426 changes shape to overcome the bias of the biasing element 446 and move the piston 422 along the normal axis AN from the open position into the closed position.

[0067] Just like in the previous embodiments, the thermal activation element 426 is disposed in the interior cavity 420 between a valve bottom 424 and the piston 422. In this embodiment, the valve bottom 424 is fastened to the valve body 414.

[0068] In Figure 22, the piston is in the open position. In the open position, thethermal activation element 426 is in the inactivated state. In this embodiment, a first surface, which is opposite a second surface, of the piston 422 defines a sealing channel 450 having a piston seal 452 disposed therein and the valve body 414 defines a sealing shelf 453 in the interior cavity 420. In Figure 22, the piston seal 452 and the sealing shelf 453 are separated and allow passage of gas through the interior cavity 420. Gas flows from outside the battery ventilation valve 410 into the interior cavity 420 through the membrane 436 and into the battery housing (not illustrated), and is expelled from the battery housing and through the battery ventilation valve 410. When the biasing element 446 is inactivated there is a gap the piston seal 452 and the under-surface of the sealing shelf 453 to allow passage of gas through the interior cavity 420.

[0069] In the example of Figure 22, the thermal activation element 426 comprises a spring that increases in length when activated, to overcome the bias of the biasing element 446 and push the piston seal 452 into contact with the sealing shelf 453 and thus the battery ventilation valve 410 is sealed (in the closed position) to prevent passage of gas through the interior cavity 420. Activation of the biasing element 446 moves the piston 422 thereby creating contact between the piston seal 452 and the under-surface of the sealing shelf 453 to prevent passage of gas through the interior cavity 420.

[0070] The header 484 comprises the header body 486, which has a first header end 490 and a second header end 492, an end wall 494 at least partially defining one or more flow apertures 496 to allow movement of gas in and out of the header 484 and thus in and out of the valve body 414 at the first header end 490. As you can see in Figure 22, a first end 432 of the valve body 414 has a plurality of couplings 498 which are received by a plurality of corresponding couplings (not shown) on the first header end 490. The plurality of couplings secure the valve body 414 in the header cavity 488.The valve body 414 of this embodiment has two exterior O-ring seals 502 to prevent the ingress and egress of gas into the battery housing between the valve body 414 and the header 484.

[0071] The header 484 also comprises a collar 500 defining an engagement surface 504 having one or more fasteners (not illustrated) engageable with an exterior surface of the battery housing at the second header end 492. From a fastening perspective, the header 484 can be quickly coupled, bolted, welded, bonded, or attached to the battery housing with various means known in the coupling / fastening art. For example, a plurality of standard threaded bolts or threaded forming bolts (e.g., M6) could be used to fasten the header 484 to the battery housing.

[0072] Referring now to Figure 25, a method 600 of hermetically sealing a battery housing with a battery ventilation valve is also disclosed. The valve comprises a valve body defining an interior cavity, a piston moveably disposed in the interior cavity, and a thermal activation element having an activation temperature. Various embodiments and features of the battery ventilation valve are described above and illustrated in the corresponding Figures. The method 600 includes the steps of: heating the thermal activation element 602; transforming the thermal activation element from a first shape to a second shape 604; and moving the piston from an open position, which allows flow of gas into and out of the battery housing, to a closed position to prevent flow of gas into and out of the battery housing 606.

[0073] The method may also include the step of providing one or more of the battery ventilation valve. Of course, the battery ventilation valve is coupled to an exterior surface of a battery housing such that the valve is in fluidic communication with an interior of the battery housing and the piston is in the open position.

[0074] The step of heating is further defined as heating the thermal activation element to a temperature of greater than about 75, about 85, or about 95 °C. As described above, the thermal activation element has an activation temperature of from about 80 to about 300, from about 85 to about 250, from about 90 to about 200, from about 90 to about 110, or from about 95 to about 105 °C. When the thermal activation element is heated to a temperature of greater than the thermal activation temperature, the thermal activation element is activated, and transforms from a first shape to a second shape. The transformation can be an increase in a length of the thermal activation element as is described at length herein. However, the transformation can be a decrease in a length of the thermal activation element or can even be forming two or more portions with the thermal activation element.

[0075] The above description is that of current examples of the disclosure. Various alterations and changes can be made without departing from the spirit and broader aspects of the disclosure as defined in the appended claims, which are to be interpreted in accordance with the principles of patent law including the doctrine of equivalents. This disclosure is presented for illustrative purposes and should not be interpreted as an exhaustive description of all examples of the disclosure or to limit the scope of the claims to the specific elements illustrated or described in connection with these examples. For example, and without limitation, any individual element(s) of the described disclosure may be replaced by alternative elements that provide substantially similar functionality or otherwise provide adequate operation. This includes, for example, presently known alternative elements, such as those that might be currently known to one skilled in the art, and alternative elements that may be developed in the future, such as those that one skilled in the art might, upon development, recognize as an alternative. Further, the disclosed examples include a plurality of features that aredescribed in concert and that might cooperatively provide a collection of benefits. The present disclosure is not limited to only those examples that include all these features or that provide all the stated benefits, except to the extent otherwise expressly set forth in the issued claims. Any reference to claim elements in the singular, for example, using the articles “a,” “an,” “the” or “said,” is not to be construed as limiting the element to the singular.

Claims

CLAIMS1. A battery ventilation valve for a battery housing, the valve comprising: a valve body defining an interior cavity disposed about a normal axis and extending between a first opening at a first end of the valve body and a second opening at a second end of the valve body; a piston moveably disposed in the interior cavity between an open position that allows flow of gas into and out of the battery housing and a closed position that prevents flow of gas into and out of the battery housing; a biasing element disposed in the interior cavity biasing the piston along the normal axis; and a thermal activation element having an activation temperature and disposed in the interior cavity; wherein the thermal activation element transforms from an inactivated state to an activated state at the activation temperature to overcome the biasing element and move the piston along the normal axis from the open position into the closed position.

2. The valve of claim 1 , further comprising a valve bottom disposed in the second opening.

3. The valve of claim 2, wherein the thermal activation element is disposed in the interior cavity between the valve bottom and the piston.

4. The valve of claim 3, wherein the biasing element biases the piston along the normal axis into the open position.

5. The valve of claim 1, wherein the valve body defines a biasing surface proximal to the first opening.

6. The valve of claim 5, wherein the biasing element is disposed between the biasing surface and the piston.

7. The valve of claim 1, wherein the activation temperature is a temperature of from about 90 to about 200 °C.

8. The valve of claim 1 , wherein the thermal activation element comprises wax.

9. The valve of claim 1 , wherein the thermal activation element comprises a spring formed with a shape memory alloy.

10. The valve of claim 1, wherein the thermal activation element has a first length in the inactivated state and a second length in the activated state, wherein the second length is greater than the first length.

11. The valve of claim 1 , wherein when the thermal activation element is activated and changes from the inactivated state to the activated state, the biasing element is overcome, and the piston is moved along the normal axis towards the first end of the valve body and into the closed position.

12. The valve of claim 1 , wherein the piston has a first surface and a second surface and the first surface of the piston defines a sealing channel having a piston seal disposed therein and the valve body defines a sealing shelf in the interior cavity, wherein the piston seal and the sealing shelf are separated when the thermal activation element is in the inactivated state and the valve is in the open position to allow passage of gas through the interior cavity and the piston seal and the sealing shelf are in contact when the thermal activation element is in the activated state and the valve is in the closed position to prevent passage of gas through the interior cavity.

13. The valve of claim 1, wherein the second end of the valve body defines an engagement surface having one or more fasteners engageable with an exterior surface of a battery housing.

14. The valve of claim 13, wherein the second end of the valve body further includes a locking rib and each of the one or more fasteners are further defined as a plurality of engagement tabs, each engagement tab having an engagement projection at least partially defining an engagement slot, wherein each of the plurality of engagement tabs is received in one of a corresponding plurality of notches in the exterior surface of the battery housing, and rotational movement of the valve moves the locking rib into a corresponding locking slot in the exterior surface of the battery housing to engage the valve and the battery.

15. The valve of claim 13, wherein the each of the one or more fasteners are further defined as a plurality of locking tabs, each of the plurality of locking tabs having a locking projection at least partially defining a locking slot and a locking tip oppositethe locking slot, wherein each of the plurality of locking tabs is received in one of a corresponding plurality of slots in the exterior surface of the battery housing and rotational movement of the valve locks the plurality of locking tabs in the corresponding plurality of slots to engage the valve and the battery.

16. The valve of claim 1, further comprising a membrane disposed in the interior cavity.

17. The valve of claim 16, further comprising a cover defining one or more flow apertures to allow movement of gas in and out of the valve body through the membrane, the cover shaped to couple to the first end of the valve body.

18. The valve of claim 17, wherein an exterior perimeter of the cover includes a plurality of attachment apertures defined by a lower rail, each aperture shaped to receive a corresponding angled tab, wherein downward pressure on the cover forces the lower rail to slide along the corresponding angled tab and snap into the aperture whereby contact between the corresponding angled tab and the lower rail secures the cover to the first end of the valve body.

19. The valve of claim 18, further comprising a seal disposed between the cover and the first end of the valve body.

20. The valve of claim 16, wherein the first end of the valve body includes an end wall defining one or more flow apertures to allow movement of gas in and out of the valve body through the membrane.

21. The valve of claim 20 further comprising a membrane mount which is shaped to couple to a feature on an interior surface of the valve body to secure the membrane between at least a portion of the end wall and the membrane mount.

22. The valve of claim 1, further comprising a header defining a header cavity disposed about the normal axis and shaped to receive the valve body.

23. The valve of claim 22, wherein the header comprises: a header body having a first header end and a second header end, an end wall at least partially defining one or more flow apertures to allow movement of gas in and out of the header and thus in and out of the valve body at the first header end, and a collar defining an engagement surface having one or more fasteners engageable with an exterior surface of a battery housing at the second header end.

24. A battery ventilation valve, the valve comprising: a valve body defining an interior cavity extending between a first opening and a second opening and disposed about a normal axis and having a biasing surface proximal to the first opening and a valve bottom proximal to the second opening and shaped to couple to a surface of a battery housing; a membrane disposed in the interior cavity;a piston moveably disposed in the interior cavity between an open position that allows flow of gas into and out of the battery housing and a closed position that prevents flow of gas into and out of the battery housing; a biasing element disposed between the biasing surface and the piston, the biasing element biasing the piston along the normal axis and into the open position; and a thermal activation element having an activation temperature and disposed in the interior cavity between the valve bottom and the piston; wherein the thermal activation element transforms from an inactivated state to an activated state at a temperature at or above the activation temperature to overcome the biasing element and move the piston along the normal axis from the open position into the closed position.

25. The valve of claim 24, wherein the activation temperature is from about 90 to about 200 °C.

26. The valve of claim 24, wherein the thermal activation element comprises wax.

27. The valve of claim 24, wherein the thermal activation element comprises a spring formed with a shape memory alloy.

28. The valve of claim 24, wherein the thermal activation element has a first length in the inactivated state and a second length in the activated state, wherein the second length is greater than the first length.

29. The valve of claim 24, wherein the thermal activation element has a first length in the inactivated state and a second length in the activated state, wherein the second length is less than the first length.

30. A method of hermetically sealing a battery housing with a battery ventilation valve, the valve comprising a valve body defining an interior cavity, a piston moveably disposed in the interior cavity, and a thermal activation element having an activation temperature, the method comprising the steps of: heating the thermal activation element; transforming the thermal activation element from a first shape to a second shape; and moving the piston from an open position, which allows flow of gas into and out of the battery housing, to a closed position to prevent flow of gas into and out of the battery housing.

31. The method of claim 30, further comprising the step of providing one or more of the battery ventilation valve.

32. The method of claim 30, further comprising the step of coupling the battery ventilation valve to an exterior surface of a battery housing such that the valve is in fluidic communication with an interior of the battery housing and the piston is in the open position.

33. The method of claim 30, wherein the step of heating is further defined as heating the thermal activation element to a temperature of greater than about 80 °C.

34. The method of claim 33, wherein the step of transforming the thermal activation element from a first shape to a second shape occurs when the thermal activation element has a temperature that is greater than the activation temperature and wherein the temperature is a temperature of from about 90 to about 200 °C.

35. The method of claim 34, wherein the step of transforming the thermal activation element from a first shape to a second shape is further defined as increasing a length of the thermal activation element.

36. The method of claim 34, wherein the step of transforming the thermal activation element from a first shape to a second shape is further defined as decreasing a length of the thermal activation element.

37. The method of claim 34, wherein the step of transforming the thermal activation element from a first shape to a second shape is further defined as forming two or more portions with the thermal activation element.

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