Patent Application
20250192341
This disclosure relates generally to traction battery packs, and more particularly to cross-member assemblies that include integrated thermal management valves with controlled opening mechanisms for controlling a flow of battery cell vent byproducts through the cross-member assemblies.
Electrified vehicles include a traction battery pack for powering electric machines and other electrical loads of the vehicle. The traction battery pack includes a plurality of battery cells and various other battery internal components that support electric vehicle propulsion.
A traction battery pack according to an exemplary aspect of the present disclosure includes, among other things, a cell stack including a plurality of battery cells arranged between a first cross-member assembly and a second cross-member assembly. The first cross-member assembly and the second cross-member assembly each include a ladder frame, a thermally insulating sheet, and a venting tape that secures the thermally insulating sheet to the ladder frame.
In a further non-limiting embodiment of the foregoing traction battery pack, the ladder frame is made of a thermoplastic material and includes a plurality of cell tab openings each sized to receive a terminal of one or more of the plurality of battery cells.
In a further non-limiting embodiment of either of the foregoing traction battery packs, the ladder frame includes a vent opening.
In a further non-limiting embodiment of any of the foregoing traction battery packs, the thermally insulating sheet includes a flap that is releasable from a first position that covers the vent opening to a second position that uncovers the vent opening in response to a flow of a battery cell vent byproduct against the flap.
In a further non-limiting embodiment of any of the foregoing traction battery packs, the flap is releasably connected to a membrane of the thermally insulating sheet by the venting tape.
In a further non-limiting embodiment of any of the foregoing traction battery packs, the ladder frame includes a stake that is received through a mounting hole of the membrane to position the membrane relative to the ladder frame.
In a further non-limiting embodiment of any of the foregoing traction battery packs, the ladder frame includes a clip that holds the membrane relative to the ladder frame.
In a further non-limiting embodiment of any of the foregoing traction battery packs, the venting tape is configured to melt to release the flap when a temperature of the battery cell vent byproduct exceeds a predefined temperature threshold.
In a further non-limiting embodiment of any of the foregoing traction battery packs, the venting tape is a coated mica tape.
In a further non-limiting embodiment of any of the foregoing traction battery packs, a first pultruded reinforcement beam is attached to the ladder frame.
In a further non-limiting embodiment of any of the foregoing traction battery packs, a second pultruded reinforcement beam is attached to the ladder frame.
In a further non-limiting embodiment of any of the foregoing traction battery packs, the thermally insulating sheet includes a flap that functions to provide a thermal control valve, and the venting tape functions to provide an opening mechanism for selectively releasing the flap from the thermally insulating sheet.
A traction battery pack according to another exemplary aspect of the present disclosure includes, among other things, a cell stack including a cross-member assembly, the cross-member assembly including a ladder frame, a thermally insulating sheet, and a venting tape configured to secure the thermally insulating sheet to ladder frame.
In a further non-limiting embodiment of the foregoing traction battery pack, a first reinforcement beam is mounted to the ladder frame. The first reinforcement beam establishes a pultrusion of the cross-member assembly.
In a further non-limiting embodiment of either of the foregoing traction battery packs, the venting tape is a coated mica tape.
In a further non-limiting embodiment of any of the foregoing traction battery packs, the venting tape is configured to provide an opening mechanism for selectively releasing a flap from the thermally insulating sheet.
In a further non-limiting embodiment of any of the foregoing traction battery packs, the venting tape is configured to provide the opening mechanism when a temperature of a battery cell vent byproduct exceeds a predefined temperature threshold.
In a further non-limiting embodiment of any of the foregoing traction battery packs, the venting tape releasably secures the flap in place to cover a vent opening of the ladder frame.
In a further non-limiting embodiment of any of the foregoing traction battery packs, the ladder frame includes a stake that is received through a mounting hole of a membrane of the thermally insulating sheet to position the membrane relative to the ladder frame.
In a further non-limiting embodiment of any of the foregoing traction battery packs, the ladder frame includes a clip that engages a notch of a membrane of the thermally insulating sheet to secure the membrane relative to the ladder frame.
The embodiments, examples, and alternatives of the preceding paragraphs, the claims, or the following description and drawings, including any of their various aspects or respective individual features, may be taken independently or in any combination. Features described in connection with one embodiment are applicable to all embodiments, unless such features are incompatible.
The various features and advantages of this disclosure will become apparent to those skilled in the art from the following detailed description. The drawings that accompany the detailed description can be briefly described as follows.
This disclosure details battery cell stack cross-member assemblies for traction battery packs. An exemplary cross-member assembly may include a thermally insulating sheet for blocking the transfer of thermal energy to adjacent structures inside the traction battery pack. The thermally insulating sheet incorporates thermal control valves in the form of releasable flaps for controlling the flow of battery cell vent byproducts during battery thermal events. A venting tape may secure the thermally insulating sheet to the cross-member assembly and may function to provide an opening mechanism for controlling the release of the flaps. These and other features are discussed in greater detail in the following paragraphs of this detailed description.
In the illustrated embodiment, the electrified vehicle 10 is depicted as a car. However, the electrified vehicle 10 could alternatively be a sport utility vehicle (SUV), a van, a pickup truck, or any other vehicle configuration. Although a specific component relationship is illustrated in the figures of this disclosure, the illustrations are not intended to limit this disclosure. The placement and orientation of the various components of the electrified vehicle 10 are shown schematically and could vary within the scope of this disclosure. In addition, the various figures accompanying this disclosure are not necessarily drawn to scale, and some features may be exaggerated or minimized to emphasize certain details of a particular component, assembly, or system.
In the illustrated embodiment, the electrified vehicle 10 is a full electric vehicle propelled solely through electric power, such as by one or more electric machines 12, without assistance from an internal combustion engine. The electric machine 12 may operate as an electric motor, an electric generator, or both. The electric machine 12 receives electrical power and can convert the electrical power to torque for driving one or more wheels 14 of the electrified vehicle 10.
A voltage bus 16 may electrically couple the electric machine 12 to a traction battery pack 18. The traction battery pack 18 is an exemplary electrified vehicle battery. The traction battery pack 18 may be a high voltage traction battery pack assembly that includes a plurality of battery cells capable of outputting electrical power to power the electric machine 12 and/or other electrical loads of the electrified vehicle 10. Other types of energy storage devices and/or output devices could alternatively or additionally be used to electrically power the electrified vehicle 10.
The traction battery pack 18 may be secured to an underbody 20 of the electrified vehicle 10. However, the traction battery pack 18 could be located elsewhere on the electrified vehicle 10 within the scope of this disclosure.
Each cell stack 22 may include a plurality of battery cells 32. The battery cells 32 of each cell stack 22 may be stacked together and arranged along a cell stack axis A. The battery cells 32 store and supply electrical power for powering various components of the electrified vehicle 10. Although a specific number of cell stacks 22 and battery cells 32 are illustrated in the various figures of this disclosure, the traction battery pack 18 could include any number of the cell stacks 22, with each cell stack 22 including any number of individual battery cells 32.
In an embodiment, the battery cells 32 are lithium-ion pouch cells. However, battery cells having other geometries (cylindrical, prismatic, etc.) and/or chemistries (nickel-metal hydride, lead-acid, etc.) could alternatively be utilized within the scope of this disclosure. The battery cells 32 can each include tab terminals that project outwardly from a battery cell housing. The tab terminals of the battery cells 32 of each cell stack 22 are connected to one another, such as by one or more busbars, for example, in order to provide the voltage and power levels necessary for achieving electric vehicle propulsion.
One or more thermal barrier assemblies 34 may be arranged along the respective cell stack axis A of each cell stack 22. The thermal barrier assemblies 34 may compartmentalize each cell stack 22 into two or more groupings or compartments of battery cells 32. Each compartment may hold one or more of the battery cells 32 of the cell stack 22.
The battery cells 32 of the cell stack 22 may be arranged between a pair of cross-member assemblies 38. Among other functions, the cross-member assemblies 38 may be configured to hold the battery cells 32 and at least partially delineate the cell stacks 22 from one another within the interior area 30 of the enclosure assembly 24.
Each cross-member assembly 38 may be configured to transfer a load applied to a side of the electrified vehicle 10, for example, for ensuring that the battery cells 32 do not become overcompressed. Each cross-member assembly 38 may be further configured to accommodate tension loads resulting from expansion and retraction of the battery cells 32. The cross-member assemblies 38 described herein are therefore configured to increase the structural integrity of the traction battery pack 18.
A vertically upper side of each cell stack 22 may interface with the enclosure cover 26, and a vertically lower side of each cell stack 22 may interface with a heat exchanger plate 40 that is positioned against a floor of the enclosure tray 28 (see
The cross-member assemblies 38 may be adhesively secured to the enclosure cover 26 and to either the heat exchanger plate 40 or the enclosure tray 28 to seal the interfaces between these neighboring components and to structurally integrate the traction battery pack 18.
The cell stack 22 may be arranged to extend along their respective cell stack axes A between opposing end plates 42 of the traction battery pack 18. One or more end plates 42 may be positioned between the end of each cell stack 22 and a longitudinally extending side wall 44 of the enclosure tray 28. The end plates 42 may therefore extend along axes that are substantially transverse (e.g. perpendicular) to the cell stack axes A of the cell stacks 22 and the cross-member assemblies 38. In some implementations, the end plates 42 are structural members that span across a majority of the length of the longitudinally extending side wall 44 of the enclosure tray 28 (see
Each cross-member assembly 38 may include a ladder frame 46 and one or more reinforcement sections. In the illustrated embodiment, the cross-member assembly 38 includes an upper or first reinforcement beam 48 and a lower or second reinforcement beam 50. However, other configurations are also contemplated within the scope of this disclosure.
The ladder frame 46 may include either a unitary or multi-piece injection molded structure. The ladder frame 46 may be made of any suitable thermoplastic material.
The ladder frame 46 may include one or more vent openings 52 (see
The ladder frame 46 may additionally include a plurality of cell tab openings 54 (see
In an assembled state of the cross-member assembly 38, both the vent openings 52 and the cell tab openings 54 are located between the first and second reinforcement beams 48, 50. However, other configurations are possible within the scope of this disclosure.
The first reinforcement beam 48 and the second reinforcement beam 50 may be mounted at separate locations of the ladder frame 46 for structurally reinforcing the cross-member assembly 38. The ladder frame 46 and the first and second reinforcement beams 48, 50 may include mateable features that facilitate the connection of the first and second reinforcement beams 48, 50 to the ladder frame 46. For example, the ladder frame 46 may include first engagement features that are configured to mesh or interdigitate with a second engagement feature of the first reinforcement beam 48 or the second reinforcement beam 50. In an embodiment, the first engagement features each include a first arrangement of fingers and slots, and the second engagement features each include a second arrangement of fingers and slots. The fingers of the first engagement features can be received in the slots of the second engagement features and vice versa in order to mount the first and second reinforcement beams 48, 50 to the ladder frame 46. Although not shown, an adhesive could be applied between the first and second engagement features for further facilitating the connection of the first and second reinforcement beams 48, 50 to the ladder frame 46.
In an embodiment, the first and second reinforcement beams 48, 50 are pultrusions, which implicates structure to these beam-like structures. A person of ordinary skill in the art having the benefit of this disclosure would understand how to structurally distinguish a pultruded beam structure from another type of structure, such as an extruded beam, for example.
The first and second first reinforcement beams 48, 50 may be manufactured as part of a pultrusion process that utilizes a glass or carbon fiber (unidirectional or multidirectional mat) and a thermoset resin. A plurality of glass or carbon fiber strands may be pulled through the thermoset resin as part of the pultrusion process for manufacturing the first and second first reinforcement beams 48, 50.
When mounted to the ladder frame 46, the first reinforcement beam 48 may establish an upper plateau 68 of the cross-member assembly 38, and the second reinforcement beam 50 may establish a lower base 70 of the cross-member assembly 38. An adhesive 72 may be applied to the upper plateau 68 and to the lower base 70 for securing the cross-member assembly 38 directly to the enclosure cover 26 and to either the heat exchanger plate 40 or the enclosure tray 28, respectively. Each cell stack 22 may therefore be structurally integrated with the enclosure assembly 24 of the traction battery pack 18 via the cross-member assemblies 38.
Each end of the ladder frame 46 may include one or more fastener housings 74 that are each sized to receive a fastener insert 76. Each fastener insert 76 may be made of a metallic material (e., steel, brass, aluminum, etc.), for example, and may be received within an opening provided by the fastener housing 74. In an embodiment, the fastener housings 74 are integrally formed (e.g., molded) features of the ladder frame 46. The first reinforcement beam 48 and the second reinforcement beam 50 may be appropriately shaped to accommodate the fastener housings 74.
Each fastener insert 76 may include a fastener opening 80 that is configured to receive a fastener (e.g., a bolt or screw, not shown) for mounting the cross-member assembly 38 and thus an associated cell stack 22 to a neighboring structure, such as one of the end plates 42, for example. The fastener may be passed through the end plate 42 and can then be accommodated within the fastener opening 80 of the fastener insert 76 for mounting the cell stack 22 to the end plate 42. This connection can help contain tensile loads that can occur over the life of the cell stack 22 as a result of battery cell expansion forces, for example.
A thermally insulating sheet 82 may be connected to the ladder frame 46 of each cross-member assembly 38 for limiting the transfer of thermal energy from the cell stack 22 to a neighboring structure, such as another cell stack, for example, thereby limiting battery cell vent byproducts and their associated heat from influencing the structural integrity of the traction battery pack 18 during battery thermal events. The thermally insulating sheet 82 may be either a unitary or multi-piece structure made of a flame resistant and heat insulating material. In an embodiment, the thermally insulating sheet 82 is a mica sheet. However, the thermally insulating sheet 82 could be made of aerogel materials, refractory ceramic fibers, or other materials or combinations of materials that are capable of providing flame resistant and heat insulation properties.
The thermally insulating sheet 82 may include a membrane 84 and a plurality of flaps 86 that are each removably connected to the membrane 84. The membrane 84 may be positioned and retained relative to the ladder frame 46 by a plurality of stakes 88, a plurality of clips 90, or both. The stakes 88 and the clips 90 may be integrally formed features of the ladder frame 46. In an embodiment, the stakes 88 and the clips 90 may protrude outwardly from sections 92 (see
The stakes 88 may be received through mounting holes 99 that are pre-formed through the membrane 84 for positioning the membrane 84 onto the ladder frame 46. The heads of the stakes 88 may subsequently be deformed, such as via heat staking or cold working, for example, to mount the membrane 84 to the ladder frame 46. The clips 90 may engage notches 97 formed in the membrane 84 for securing the membrane 84 relative to the ladder frame 46.
Referring now primarily to
The venting tape 94 may additionally releasably secure the flaps 86 relative to the membrane 84 of the thermally insulating sheet 82. It is therefore not necessary, in at least some implementations, to directly connect the flaps 86 to the membrane 84 with bridges, hinges, or the like.
In an embodiment, the venting tape 94 is a coated mica tape. In another embodiment, the venting tap 94 is a multi-layered tape that can include a thermally insulating outer layer and an acrylic based adhesive. The venting tap 94 may be capable of withstanding temperatures up to about 150 degrees C. However, other types of venting tapes could be utilized within the scope of this disclosure.
During a battery thermal event such as schematically shown in
The flaps 86 are therefore configured to function as thermal control valves, and the venting tape 94 is configured to function as an opening mechanism for selectively releasing the flaps 86 during battery thermal events. A controlled flow of the battery cell vent byproducts V can therefore be established through the cross-member assembly 38 during battery thermal events of the traction battery pack 18.
Although only a single flap 86 is shown as being released to provide controlled venting in
During the battery thermal event, the battery cell vent byproducts V can initially move in a first direction D1 toward the venting tape 94. After contacting the backside of the venting tape 94, melting portions of the venting tape 94, and passing through the exposed opening 100 created by the release of the flap 86, the battery cell vent byproducts V can be redirected to flow in a second direction D2 that is different from the first direction D1. Battery cell vent byproducts V moving in the second direction D2 are moving, in this example, toward a flap 86B that is adjacent to the one released from the remaining portions of the thermally insulating sheet 82. Motive forces associated with the battery cell vent byproducts V may be sufficient to maintain the flap 86B in the closed position relative to the membrane 84, thereby preventing the battery cell vent byproducts V from passing back into the cell stack 22.
In some embodiments, a foam layer 96 (see, e.g.,
The exemplary cross-member assemblies of this disclosure include a thermally insulating sheet for blocking the transfer of thermal energy from cell stack-to-cell stack within a traction battery pack. The thermally insulating sheet incorporates thermal control valves in the form of releasable flaps for controlling the flow of battery cell vent byproducts during battery thermal events. A venting tape may function as an opening mechanism for releasing the flaps and allowing the vent byproducts to flow through the cross-member assembly.
Although the different non-limiting embodiments are illustrated as having specific components or steps, the embodiments of this disclosure are not limited to those particular combinations. It is possible to use some of the components or features from any of the non-limiting embodiments in combination with features or components from any of the other non-limiting embodiments.
It should be understood that like reference numerals identify corresponding or similar elements throughout the several drawings. It should be understood that although a particular component arrangement is disclosed and illustrated in these exemplary embodiments, other arrangements could also benefit from the teachings of this disclosure.
The foregoing description shall be interpreted as illustrative and not in any limiting sense. A worker of ordinary skill in the art would understand that certain modifications could come within the scope of this disclosure. For these reasons, the following claims should be studied to determine the true scope and content of this disclosure.
This disclosure claims priority to U.S. Provisional Application No. 63/607,888, which was filed on Dec. 8, 2023 and is incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 63607888 | Dec 2023 | US |
