Thermal barrier assembly for traction battery pack

Abstract

The present disclosure provides a thermal barrier assembly for a traction battery pack. A thermal barrier assembly for a traction battery pack includes a frame extending longitudinally along an axis; and an expandable element, the expandable element being secured to the frame. The expandable element is configured to expand against the structure in response to a battery cell venting event to prevent venting byproducts from flowing through a gap between the structure and the frame.

Description

Technical Field

[0001] The present disclosure generally relates to a thermal barrier assembly having an inflatable element that expands to shield areas of a battery array from exhaust byproducts emitted from other battery arrays. Background Art

[0002] Traction battery packs for electrified vehicles may include groups of battery cells arranged in one or more cell stacks. Thermal barriers may be incorporated into traction battery packs to help manage heat. Summary of the Invention

[0003] In some aspects, the technology described herein relates to a thermal barrier assembly for a traction battery pack, the thermal barrier assembly comprising: a frame extending longitudinally along an axis; and an expandable element secured to the frame, the expandable element configured to expand against a structure in response to a battery cell venting event to prevent exhaust byproducts from flowing through a gap between the structure and the frame.

[0004] In some aspects, the technology described herein relates to a thermal barrier assembly wherein the frame has an H-shaped axial cross-section.

[0005] In some aspects, the technology described herein relates to a thermal barrier assembly wherein the frame is a polymer-based material.

[0006] In some aspects, the technology described herein relates to a thermal barrier assembly wherein the expandable element is a foam.

[0007] In some aspects, the technology described herein relates to a thermal barrier assembly that also includes a mica shield sandwiched between the foam and the frame.

[0008] In some aspects, the technology described herein relates to a thermal barrier assembly wherein the structure is an enclosure wall.

[0009] In some aspects, the technology described herein relates to a thermal barrier assembly wherein the enclosure wall is an enclosure cover.

[0010] In some aspects, the technology described herein relates to a thermal barrier assembly wherein the inflatable element is configured to inflate to redirect a flow of exhaust byproducts emitted from at least one battery cell within a first array so as to avoid flowing through array terminals of a second array, with the frame and the inflatable element disposed between the first array and the second array.

[0011] In some aspects, the technology described herein relates to a thermal barrier assembly wherein the expandable element is secured to a first side of the frame facing the first array, a second side of the frame facing the second array, and a third side of the frame facing the structure.

[0012] In some aspects, the technology described herein relates to a thermal barrier assembly wherein the frame is secured to a beam between the first array and the second array.

[0013] In some aspects, the technology described herein relates to a thermal barrier assembly that also includes a biasing member and a seal assembly, the biasing member configured to bias the seal assembly against the structure.

[0014] In some aspects, the technology described herein relates to a thermal barrier assembly that includes a sealing element retained within a tray, the biasing member biasing the tray and sealing element against the structure.

[0015] In some aspects, the technology described herein relates to a thermal barrier assembly wherein the biasing member, the tray, and the sealing element are each at least partially received within a channel of the frame.

[0016] In some aspects, the technology described herein relates to a thermal barrier assembly wherein the biasing member is a linear wave spring.

[0017] In some aspects, the technology described herein relates to a method of shielding an area within a traction battery pack, the method comprising: in response to a venting event, inflating an inflatable element against a structure within the traction battery pack to shield a battery array from venting byproducts emitted from at least one battery cell in another battery array.

[0018] In some aspects, the technology described herein relates to a method in which the inflatable element is secured to a frame, and the inflatable element is expanded against the structure to prevent the exhaust byproducts from flowing through a gap between the frame and the structure.

[0019] In some aspects, the technology described herein relates to a method that also includes biasing a sealing element away from the frame and against the structure.

[0020] In some aspects, the technology described herein relates to a method wherein the structure is a wall of an enclosure.

[0021] In some aspects, the technology described herein relates to a method wherein the expandable element is a foam.

[0022] The embodiments, examples and alternatives of the preceding paragraphs, claims or following description and drawings, including any of their various aspects or corresponding individual features, may be taken independently or in any combination. Features described in conjunction with one embodiment apply to all embodiments, unless such features are incompatible. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The various features and advantages of the disclosed examples will become apparent to those skilled in the art based on the detailed description. The drawings accompanying the detailed description can be briefly described as follows:

[0024] Figure 1 A side view of an electrified vehicle is shown.

[0025] Figure 2 An exemplary embodiment according to the present disclosure is shown. Figure 2 An expanded perspective view of the battery pack for an electric vehicle.

[0026] Figure 3 Shown along Figure 2 A cross-sectional view taken along line 3-3 in FIG.

[0027] Figure 4 According to an exemplary embodiment, Figure 2 A perspective view of the thermal barrier assembly of a battery pack.

[0028] Figure 5 Shown Figure 4 Expanded view of the thermal barrier assembly.

[0029] Figure 6 Shown after the expandable element of the thermal barrier assembly has expanded Figure 3 Cross-sectional view of .

[0030] Figure 7 A cross-sectional view through a thermal barrier assembly is shown according to another exemplary embodiment. DETAILED DESCRIPTION

[0031] This disclosure details an exemplary thermal barrier assembly for use within a traction battery pack. The thermal barrier system includes an expandable element that expands in response to a battery cell venting event to help protect an area from venting byproducts. Protected areas, such as those near array terminals, can help manage thermal energy within the traction battery pack and prevent venting events from cascading to other cells.

[0032] refer to Figure 1 The electrified vehicle 10 includes a battery pack 14, an electric motor 18, and wheels 22. The battery pack 14 supplies power to the electric motor 18, which converts the electricity into mechanical power to drive the wheels 22.

[0033] In the exemplary embodiment, the battery pack 14 is secured to the underbody 26 of the electrified vehicle 10. In other examples, the battery pack 14 may be located elsewhere on the electrified vehicle 10.

[0034] The electrified vehicle 10 is a pure electric vehicle. In other examples, the electrified vehicle 10 is a hybrid electric vehicle that selectively uses torque provided by an internal combustion engine (as an alternative to or in addition to the electric motor) to drive the wheels. In general, the electrified vehicle 10 can be any type of vehicle having a battery pack.

[0035] Now refer to Figure 2 and Figure 3 , the battery pack 14 includes a plurality of battery arrays 30 held within a battery pack housing 34. In the exemplary embodiment, the housing 34 includes a housing cover 38 and a housing tray 42. The housing cover 38 is secured to the housing tray 42 to provide an interior area 44 that houses the battery arrays 30. The housing cover 38 may be secured to the housing tray 42 using, for example, mechanical fasteners (not shown).

[0036] Each of the battery arrays 30 includes a plurality of cells along a corresponding stack axis A. A A plurality of battery cells 50 (or simply "cells") are stacked side-by-side relative to each other. The battery cells 50 store and supply power. Although a specific number of battery arrays 30 and cells 50 are shown in various figures of this disclosure, the battery pack 14 may include any number of battery arrays 30 having any number of individual cells 50.

[0037] In one embodiment, the battery cell 50 is a lithium-ion pouch cell. However, battery cells having other geometries (cylindrical, prismatic, etc.), other chemistries (nickel-metal hydride, lead acid, etc.), or both may alternatively be used within the scope of the present disclosure.

[0038] The example battery pack 14 includes a crossbar 54 disposed between the arrays 30. The example crossbar 54 is parallel to the cell stack axis A. A The crossbeam 54 and the battery cell stack axis A A Extends in the vehicle transverse direction (ie, from the driver's side to the passenger's side).

[0039] Each battery array 30 includes an array cover 58. Side flanges 62 of the array cover 58 project outwardly above the crossbar 54. Mechanical fasteners 66 extend through the side flanges 62 to engage the crossbar 54 and help secure the battery array 30 within the interior region 44.

[0040] Bus bars 70 electrically connect the array 30 together within the interior region 44. The bus bars 70 connect to array terminals 74 of the battery array 30. The array terminals 74 extend into the array 30 and may provide access to and from the battery array 30.

[0041] At times, pressure and heat may build up within one or more of the battery cells 50 in the battery pack 14. This may cause the battery cells 50 to expel exhaust byproducts, which may include gases and debris.

[0042] The exhaust byproducts may be exhausted from the associated battery cells 50 through designated vents 76 within the housing (such as a membrane that yields in response to an increase in pressure) or through a ruptured region of the associated battery cells 50. The battery pack 14 experiences a venting event when one or more of the battery cells 50 vents by exhausting exhaust byproducts. The exhaust byproducts may move from the vents 76 in the battery cells 50 through the vents 80 in the corresponding array cover 58.

[0043] Now refer to Figures 4 to 6 And continue to refer to Figure 1 and Figure 2 , thermal barrier assemblies 78 are mounted atop crossbars 54. In this example, each of thermal barrier assemblies 78 includes a plurality of thermal barrier assemblies 78 along a barrier axis A. B A longitudinally extending frame 82 and an expandable member 86 secured to the frame 82 .

[0044] In this example, the expandable member 86 does not extend the entire longitudinal length of the frame 82, but rather extends over one or more portions proximate one of the array terminals 74. The expandable member 86 may extend over a notch in the frame 82.

[0045] The expandable element 86 can be a foam, such as a ceramic or silicone foam with an intumescent additive, for example. When exposed to sufficient thermal energy, such as that associated with a venting event, the expandable element 86 can expand. In some examples, the expandable element 86 is activated to expand at a temperature in the range of 160 degrees Celsius to 200 degrees Celsius. In some examples, the expandable element 86 can expand 1.5 to 4 times its original size.

[0046] Figure 6 The inflatable element 86 is shown after being inflated by exhaust byproduct streams F emitted from battery cells 50 within one of the arrays 30 during an exhaust event. The inflatable element 86 expands against the structure. This can protect the array terminals 74A from exhaust byproduct streams F emitted from at least one battery cell 50 in an adjacent battery array 30. The inflatable element 86 can also protect other areas, such as the low-voltage connector 84 of the battery array 30.

[0047] In this example, the structure against which the expandable element 86 expands is a wall of the housing 34, and specifically an underside 90 of the housing cover 38, which in this example is lined with a mica sheet.

[0048] The expansion of the expandable element 86 can fill the gap G between the housing cover 38 and the frame 82 to prevent the exhaust byproduct flow F from moving through the gap G to reach the terminal 74A. The flow F is redirected axially away from the terminal 74A and into the channel in the array 30 associated with the terminal 74A of the adjacent array. Directing the flow F away from these channels can help prevent the exhaust byproducts from entering the channels and increasing the thermal energy level of the adjacent array 30, which can reduce the likelihood of a ventilation event cascading to one or more battery cells 50 of the adjacent array 30. The exhaust byproduct flow F can be rerouted axially, which dissipates the thermal energy, rather than moving directly to a location adjacent to the array terminal 74 of the adjacent array 30. The exhaust byproducts are ultimately exhausted from the battery pack 14 through, for example, the housing vents.

[0049] In this example, flow F may cause cover 38 to lift and move upward away from array 30 and frame 82, thereby increasing the size of gap G from before the ventilation event. Use of inflatable element 86 ensures that the increased size of gap G is blocked.

[0050] The frame 82 of the thermal barrier assembly 78 has an H-shaped cross-sectional profile with an upwardly opening channel 94 and a downwardly opening channel 98. For purposes of this disclosure, upward and downward are referenced to the ground and the orientation of the battery pack 14 when installed in the vehicle 10.

[0051] The frame 82 can be a polymer-based material. In some examples, the frame 82 is an extruded structure.

[0052] In this example, one or more mechanical fasteners 102 extend through holes in the frame 82 to engage corresponding cross-members 54 and secure the thermal barrier assembly 78 .

[0053] In this example, a support structure 106 is disposed within the channel 94. The support structure 106 enhances the structural integrity of the thermal barrier assembly 78. However, the support structure 106 is not required.

[0054] Segments of the expandable element 86 are disposed on selected areas on the horizontally facing side of the frame 82. The segments of the expandable element 86 are wrapped over the top side of the frame 82. Example embodiments include segments of the expandable element 86 on opposite sides of the frame 82. In other examples, segments of the expandable element 86 are disposed on only one side of the frame 82. For example, an adhesive may be used to secure the expandable element.

[0055] In the exemplary embodiment, segments of the mica shield 110 are sandwiched between segments of the expandable element 86 and the frame 82 on the horizontally facing side of the frame 82. The mica shield 110 can help provide a barrier to the exhaust byproduct stream F moving toward the array terminals, and in particular, to particulates within the exhaust byproduct stream F. In this example, the mica shield 110 is not wrapped around the top of the frame 82 because particulates within the stream F are less likely to contact the top of the frame 82. In other examples, the mica shield 110 can be wrapped around the frame 82.

[0056] Now refer to Figure 7 In another exemplary embodiment, the thermal barrier assembly 78A includes a biasing member 118 at least partially received within the channel 94 of the frame 82 and a biased seal assembly 122. The biased seal assembly 122 includes a sealant 126 held within a tray 130. The sealant 126 may be a foam that expands in response to thermal energy. The biasing member 118 may press the sealant 126 of the biased seal assembly 122 against the wall of the housing 34 to help ensure that any gaps are blocked during a discharge event.

[0057] In this example, the biasing member 118 is a coil spring. In another example, the biasing member 118 can be a linear wave spring or a metal-based container having a spring or biasing function.

[0058] The foregoing description is illustrative rather than restrictive in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art, and such variations and modifications do not necessarily depart from the essence of the present disclosure. Therefore, the scope of protection afforded to the present disclosure should be determined solely by studying the appended claims.

Claims

1. A thermal barrier assembly for a traction battery pack, comprising: a frame extending longitudinally along an axis; as well as An inflatable member is secured to the frame, the inflatable member being configured to inflate against the structure in response to a battery cell venting event to inhibit the flow of venting byproducts through a gap between the structure and the frame.

2. The thermal barrier assembly of claim 1 , wherein the frame has an H-shaped axial cross-section.

3. The thermal barrier assembly of claim 1 , wherein the frame is a polymer-based material.

4. The thermal barrier assembly of claim 1 , wherein the expandable element is foam, and optionally further comprising a mica shield sandwiched between the foam and the frame.

5. The thermal barrier assembly of claim 1 , wherein the structure is an enclosure wall, and optionally, wherein the enclosure wall is an enclosure cover.

6. The thermal barrier assembly of claim 1 , wherein the expandable element is configured to expand to redirect a flow of exhaust byproducts emitted from at least one battery cell within a first array so as to avoid flowing through array terminals of a second array, the frame and the expandable element being disposed between the first array and the second array, and optionally, wherein the expandable element is secured to a first side of the frame facing the first array, a second side of the frame facing the second array, and a third side of the frame facing the structure.

7. The thermal barrier assembly of claim 6, wherein the frame is secured to a beam between the first array and the second array.

8. The thermal barrier assembly of claim 1, further comprising a biasing member and a seal assembly, the biasing member being configured to bias the seal assembly against the structure.

9. The thermal barrier assembly of claim 8, wherein the seal assembly includes a sealing element retained within a tray, the biasing member biasing the tray and the sealing element against the structure.

10. The thermal barrier assembly of claim 9, wherein the biasing member, the tray, and the sealing element are each at least partially received within a channel of the frame, and optionally wherein the biasing member is a linear wave spring.

11. A method of protecting an area within a traction battery pack, comprising: In response to a venting event, the inflatable element is inflated against a structure within the traction battery pack to shield the battery array from venting byproducts emitted from at least one battery cell in another battery array.

12. The method of claim 11, wherein the inflatable element is secured to a frame and the inflatable element is inflated against the structure to prevent the exhaust byproducts from flowing through a gap between the frame and the structure.

13. The method of claim 12, further comprising biasing a sealing element away from the frame and against the structure.

14. The method of claim 11, wherein the housing structure is a wall of a housing.

15. The method of claim 11, wherein the expandable element is foam.

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