Pressure equalizing device for traction battery pack

Abstract

The invention provides a pressure equalizing device for a traction battery pack. A traction battery pack includes: a housing assembly; and a pressure equalization device, the pressure equalization device being received within a wall of the housing assembly. The pressure equalization device includes a housing assembly and a flow restrictor configured to restrict flow through the housing assembly during a battery thermal event of the traction battery pack.

Description

Technical Field

[0001] The present disclosure relates generally to electrified vehicle traction battery packs and, more particularly, to pressure equalization devices for traction battery packs. Background Art

[0002] A high voltage traction battery pack typically powers the electric motor and other electrical loads of an electrified vehicle. The traction battery pack includes a plurality of battery cells and various other battery internal components housed within a housing assembly for supporting the electric propulsion of the vehicle. The housing assembly is sealed but vented to prevent moisture from accumulating within the interior of the battery pack. Summary of the invention

[0003] In some aspects, the technology described herein relates to a traction battery pack, comprising: a housing assembly; and a pressure equalization device received within a wall of the housing assembly, the pressure equalization device comprising a housing assembly and a flow restrictor configured to limit flow through the housing assembly during a battery thermal event of the traction battery pack.

[0004] In some aspects, the technology described herein relates to a traction battery pack wherein the current limiter is a disk having an opening.

[0005] In some aspects, the technology described herein relates to a traction battery pack wherein the pressure equalization device includes an inner hole extending from an inlet to an outlet, and the diameter of the opening is smaller than the diameter of the inner hole.

[0006] In some aspects, the technology described herein relates to a traction battery pack wherein the current limiter is disposed externally of the housing assembly.

[0007] In some aspects, the technology described herein relates to a traction battery pack wherein the flow restrictor is configured to limit flow through the pressure equalization device from 78% to 88%.

[0008] In some aspects, the technology described herein relates to a traction battery pack, wherein the housing assembly includes an engagement section that interfaces with a wall of the housing assembly and an outer section that protrudes outward from the wall, the engagement section providing an inlet to the housing assembly, the outer section providing an outlet from the housing assembly, and the flow restrictor is configured to limit the flow between the inlet and the outlet.

[0009] In some aspects, the technology described herein relates to a traction battery pack that also includes a membrane retained within the housing assembly and covering the outlet.

[0010] In some aspects, the technology described herein relates to a traction battery pack wherein the flow restrictor is configured to restrict flow to less than an amount that may flow through the outlet covered by the membrane.

[0011] In some aspects, the technology described herein relates to a traction battery pack wherein the membrane is a water-impermeable membrane retained within the housing assembly.

[0012] In some aspects, the technology described herein relates to a traction battery pack wherein the water-impermeable membrane is configured to allow fluid to exit the pressure equalization device.

[0013] In some aspects, the technology described herein relates to a traction battery pack wherein the current limiter is sandwiched between the engagement section and the exterior section.

[0014] In some aspects, the technology described herein relates to a traction battery pack in which the engagement section is secured to the outer section by a press fit.

[0015] In some aspects, the technology described herein relates to a traction battery pack wherein the engagement section is mounted to the wall by a twist lock.

[0016] In some aspects, the technology described herein relates to a traction battery pack wherein the housing assembly is dome-shaped, and further wherein the wall is part of a housing tray of the housing assembly.

[0017] In some aspects, the technology described herein relates to a traction battery pack that includes a plurality of battery arrays housed within a housing assembly.

[0018] In some aspects, the technology described herein relates to a traction battery pack flow control method, comprising: receiving a first flow at an inlet of a pressure equalization device, the first flow coming from an interior of the battery pack; limiting the first flow to a second flow that is less than the first flow; and allowing the second flow to move through an outlet of the pressure equalization device.

[0019] In some aspects, the technology described herein relates to a traction battery pack flow control method in which an outlet is covered by a membrane.

[0020] In some aspects, the technology described herein relates to a traction battery pack flow control method, wherein the restriction is performed by directing the flow through an opening in a flow restrictor.

[0021] In some aspects, the technology described herein relates to a traction battery pack flow control method.

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

[0023] The various features and advantages of the present 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 An electrified vehicle is schematically shown.

[0025] Figure 2 yes Figure 1 A perspective view of a traction battery pack for an electrified vehicle.

[0026] Figure 3 is a perspective view of another exemplary traction battery pack.

[0027] Figure 4 It passes through Figure 2 4-4 is a cross-sectional view of section 4-4 and illustrates features associated with a pressure equalization device for a traction battery pack according to an exemplary embodiment of the present disclosure.

[0028] Figure 5 Shown from Figure 4 A perspective view of a flow restrictor of a pressure equalization device.

[0029] Figure 6 Shows Figure 4 A perspective view of a pressure equalization device.

[0030] Figure 7 shows the through housing assembly and Figure 4 Cross-sectional view of a flow restrictor of a pressure equalization device. DETAILED DESCRIPTION

[0031] The present disclosure details an exemplary traction battery pack design for use in an electrified vehicle. An exemplary traction battery pack may include a housing assembly establishing an interior, and a battery array housed within the interior.

[0032] To equalize the pressure inside the battery pack during normal battery operation, a pressure equalization device may be disposed within the walls of the housing assembly. These and other features are discussed in more detail in the following paragraphs of this detailed description.

[0033] Figure 1An electrified vehicle 10 is schematically shown. The electrified vehicle 10 may include any type of electrified powertrain. In an embodiment, the electrified vehicle 10 is a battery electric vehicle (BEV). However, the concepts described herein are not limited to BEVs and may be extended to other electrified vehicles, including but not limited to hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), fuel cell vehicles, and the like. Therefore, although not specifically shown in the exemplary embodiment, the electrified vehicle 10 may be equipped with an internal combustion engine that may be employed alone or in combination with other power sources to propel the electrified vehicle 10.

[0034] In the illustrated embodiment, the electrified vehicle 10 is a sport utility vehicle (SUV). However, the electrified vehicle 10 may alternatively be a sedan, a van, a pickup truck, or any other vehicle configuration. Although specific component relationships are shown in the drawings of the present disclosure, the drawings are not intended to limit the present disclosure. The placement and orientation of the various components of the electrified vehicle 10 are schematically shown and may vary within the scope of the present disclosure. In addition, the various drawings attached to the present disclosure are not necessarily drawn to scale, and some features may be exaggerated or minimized to emphasize certain details of a particular component or system.

[0035] In the illustrated embodiment, the electrified vehicle 10 is a pure electric vehicle that is propelled solely by electricity, such as by one or more electric machines 12, without any assistance from an internal combustion engine. The electric machines 12 may operate as electric motors, generators, or both. The electric machines 12 receive electricity and may convert the electricity into torque for driving one or more wheels 14 of the electrified vehicle 10.

[0036] Voltage bus 16 may electrically couple electric machine 12 to traction battery pack 18. Traction battery pack 18 is an exemplary electrified vehicle battery. Traction battery pack 18 may be a high voltage traction battery pack that includes one or more battery arrays 20 (i.e., battery assemblies or groups of rechargeable battery cells 26) capable of outputting electrical power to power electric machine 12 and / or other electrical loads of electrified vehicle 10. Other types of energy storage devices and / or output devices may alternatively or additionally be used to power electrified vehicle 10.

[0037] The battery cells 26 may be stacked side by side along a stacking axis to construct a group of battery cells 26, sometimes referred to as a "cell stack." Figure 1 In the highly schematic depiction of FIG. 2 , the battery cells 26 are stacked into the page in one direction to construct each battery array 20 , and thus the battery array 20 extends in the transverse direction of the vehicle. However, other configurations are possible.

[0038] The total number of battery arrays 20 and battery cells 26 provided within the traction battery pack 18 is not intended to limit the present disclosure. In an embodiment, the battery cells 26 of each battery array 20 are prismatic lithium-ion cells. However, within the scope of the present disclosure, battery cells having other geometries (cylindrical, pouch, etc.), other chemistries (nickel metal hydride, lead acid, etc.), or both may alternatively be utilized.

[0039] The traction battery pack 18 may be secured to an underbody 22 of the electrified vehicle 10. However, the traction battery pack 18 may be located elsewhere on the electrified vehicle 10 within the scope of the present disclosure.

[0040] The housing assembly 24 houses the battery array 20 of the traction battery pack 18. The housing assembly 24 may be a sealed housing and may embody any size, shape, and configuration within the scope of the present disclosure.

[0041] In an exemplary embodiment, the housing assembly 24 includes a housing cover 28 and a housing tray 30. The housing cover 28 and the housing tray 30 can together establish an interior I for accommodating the battery array 20 and other battery internal components of the traction battery pack 18 (e.g., bus electrical center, battery electronic control module, wiring, connectors, etc.).

[0042] During assembly of the traction battery pack 18, the housing cover 28 may be secured to the housing tray 30 at an interface 32 therebetween. The interface 32 may substantially surround the interior I. In some embodiments, mechanical fasteners 34 may be used to secure the housing cover 28 to the housing tray 30, although other fastening methods (adhesion, etc.) may also be suitable for this purpose.

[0043] Reference now Figure 2 , and continue to refer to Figure 1 , the traction battery pack 18 may include one or more pressure equalization devices 36. Although two pressure equalization devices 36 are shown, the traction battery pack 18 may include a greater or lesser number of such devices.

[0044] Each pressure equalization device 36 can be disposed within a wall 38 of the housing assembly 24. In one embodiment, the wall 38 is a portion of the housing tray 30. In another embodiment, the wall 38 is a portion of the housing cover 28 (see FIG. Figure 3 ). The exact mounting location of each pressure equalization device 36 may vary and is therefore not intended to limit the present disclosure.

[0045] The pressure equalizing devices 36 may be secured to the wall 38 in any manner. In the exemplary embodiment, each pressure equalizing device 36 is secured within the wall 38 via a twist-lock mount. However, the pressure equalizing devices 36 may alternatively or additionally be mounted via mechanical fasteners, cam locks, adhesives, or the like.

[0046] Each pressure equalization device 36 is configured to equalize pressure between the interior I of the traction battery pack 18 and the atmosphere A outside the traction battery pack 18. For example, during normal battery operation, the pressure equalization devices 36 may allow flow (e.g., air) to flow into and out of the housing assembly 24 while preventing moisture, particulate contaminants, etc. from entering the interior I of the traction battery pack 18.

[0047] There may be some operating conditions where the pressure and thermal energy within the interior I increase rapidly. For example, a battery thermal event may occur during an over-temperature, over-charge, or over-discharge condition of the battery cell 26, or during other battery cell conditions. During these conditions, battery ventilation byproducts may be released from one or more battery cells 26 of the battery array 20. Allowing the ventilation byproducts to flow completely through the pressure equalization device 36 may damage the integrity of the pressure equalization device 36. Therefore, the present disclosure is directed to a pressure equalization device that is capable of providing pressure equalization during normal battery operation and providing a controlled flow of battery ventilation byproducts through the pressure equalization device during a battery thermal event.

[0048] Reference now Figures 4 to 7 And continue to refer to Figures 1 to 3 , the example pressure equalization device 36 includes a housing assembly 40, a water-impermeable membrane 42, and a flow restrictor 44. The housing assembly 40 may include an internal bore 46. The water-impermeable membrane 42 and the flow restrictor 44 are housed within different sections of the internal bore 46. The flow restrictor 44 limits the possible flow through the internal bore 46 of the pressure equalization device 36 relative to the amount that could flow through the internal bore 46 without the flow restrictor 44.

[0049] The housing assembly 40 may be a plastic component or a metal component and may include a single-piece structure or a multi-piece structure. In an embodiment, the housing assembly 40 is dome-shaped. However, the size and shape of the housing assembly 40 are not intended to limit the present disclosure.

[0050] The example housing assembly 40 is oriented along the central axis Z. The example housing assembly 40 includes an engagement section 48 that interfaces with the wall 38 of the housing assembly 24 and an outer section 50 that protrudes outwardly from the wall 38 (see FIG. Figure 2 ).

[0051] The groove 52 is formed on the rear surface 56 of the engagement section 48. The seal 54 is received in the groove 52. The seal 54 can be configured to seal the interface between the wall 38 of the housing assembly 24 and the housing assembly 40 of the pressure equalization device 36. The seal 54 can be a hole seal, an adhesive seal, a press-fit seal, a bearing gasket, a formed-in-place sealant, or any other suitable sealing device / sealant.

[0052] The example engagement section 48 of the housing assembly 40 includes an attachment portion 58 surrounded by a groove 52. The attachment portion 58 includes raised features configured to establish a twist-lock attachment for securing the housing assembly 40 to the wall 38 of the shell assembly 24. When the housing assembly 40 is secured to the wall 38, the restrictor 44 of the pressure equalization device is external to the wall 38 of the shell assembly 24.

[0053] The inner bore 46 opens to the atmosphere A at an outlet 62 formed in the outer section 50 of the housing assembly 40. The outlet 62 may be provided by a plurality of individual openings. The inner bore 46 opens to the interior I of the traction battery pack 18 at an inlet 64 provided by a plurality of openings in the joining section 48. The inner bore 46 extends from the inlet 64 to the outlet 62.

[0054] The water-impermeable membrane 42 is retained within the outer section 50 of the housing assembly 40 . The water-impermeable membrane 42 spans the outlet 62 , such that flow exiting the pressure equalization device 36 through the outlet 62 passes through the water-impermeable membrane 42 .

[0055] The water-impermeable membrane 42 may be a patch, a filter, or some other porous membrane that allows gas to flow into and out of the housing assembly 24 during normal battery operation while preventing moisture, particulate contaminants, etc. from flowing through the inner pores 46 to the interior I of the traction battery pack 18. Thus, the water-impermeable membrane 42 provides pressure equalization between the interior I of the traction battery pack 18 and the atmosphere A.

[0056] The restrictor 44 is received within the bore 46 at a location between the inlet 64 provided by the attachment portion 58 and the water-impermeable membrane 42. In this example, the restrictor 44 is a disk including an opening 66 having a diameter d that is less than the smallest diameter D of the bore 46.

[0057] The flow restrictor 44 is sandwiched between the engagement section 48 of the housing assembly 40 and the outer section 50 of the housing assembly 40. A press fit may be used to secure the outer section 50 to the engagement section 48 with the flow restrictor 44 captured therebetween.

[0058] Gas received from the interior I of the traction battery pack 18 may enter the pressure equalization device 36 through the inlet 64, flow through the inner hole 46 and flow through the opening 66 of the restrictor 44. The gas that has moved through the opening 66 may exit the pressure equalization device 36 at the outlet 62 while passing through the water-impermeable membrane 42.

[0059] During a battery thermal event, battery ventilation byproducts V released by the battery cells 26 can rapidly increase the pressure inside the interior I of the traction battery pack 18. The amount of flow moving through the inlet 64 increases accordingly.

[0060] The restrictor 44 having the opening 66 restricts the flow during the battery thermal event so that the area of ​​the pressure equalization device 36 and in particular the water-impermeable membrane 42 is not exposed to all of the flow associated with the battery thermal event. The restrictor 44 is configured to limit the flow of the byproduct V to less than the amount that would flow through the outlet 62 in the absence of the restrictor 44. In particular, the restrictor 44 is configured to limit the flow through the pressure equalization device from 78% to 88%.

[0061] The flow restrictor 44 prevents at least some of the battery ventilation byproducts 70 released by the battery cells 26 of the traction battery pack 18 during a battery thermal event from exiting the pressure equalization device 36 through the outlet 62. Thus, the battery ventilation byproducts 70 may be forced to exit the traction battery pack 18 only through a separate ventilation channel as part of a dedicated ventilation management strategy for the traction battery pack 18. The opening 66 may be sized to allow only an amount of battery ventilation byproducts 70 that does not compromise the integrity of the water-impermeable membrane 42.

[0062] Thus, the pressure equalizing device 36 receives a first flow rate from the interior I at the inlet 64 . Within the pressure equalizing device 36 , the restrictor 44 limits the first flow rate to allow a second flow rate that is less than the first flow rate moving through the outlet 62 of the pressure equalizing device 36 .

[0063] The exemplary traction battery pack of the present disclosure incorporates a pressure equalization device that has a dual function of equalizing the pressure inside the traction battery pack during normal battery conditions and inhibiting the release of battery ventilation byproducts during battery thermal events. The proposed device is relatively simple and inexpensive to assemble and manufacture, and does not require complex modifications to the battery pack sealing strategy. The flow restrictor 44 can protect the water-impermeable membrane 42 in particular without incorporating a relatively complex flow shutoff mechanism into the pressure equalization device 36.

[0064] Although different non-limiting embodiments are shown as having specific components or steps, the embodiments of the present disclosure are not limited to these specific combinations. Some of the components or features from any one of the non-limiting embodiments may be used in combination with features or components from any one of the other non-limiting embodiments.

[0065] It should be understood that like reference numerals identify corresponding or similar elements throughout the several drawings.It should be understood that although particular component arrangements are disclosed and shown in these exemplary embodiments, other arrangements may also benefit from the teachings of the present disclosure.

[0066] The above description should be interpreted as illustrative and not in any limiting sense. It will be appreciated by those skilled in the art that certain modifications may occur within the scope of the present disclosure. For these reasons, the attached claims should be studied to determine the true scope and content of the present disclosure.

Claims

1. A traction battery pack, comprising: Housing assembly; as well as A pressure equalization device is received within a wall of the housing assembly, the pressure equalization device including a housing assembly and a flow restrictor configured to limit flow through the housing assembly during a battery thermal event of the traction battery pack.

2. A traction battery pack as claimed in claim 1, wherein the restrictor is a disc having an opening, and optionally wherein the pressure equalization device comprises an inner hole extending from the inlet to the outlet, the opening having a diameter smaller than a diameter of the inner hole. 3 . The traction battery pack of claim 1 , wherein the current limiter is disposed outside the housing assembly.

4. The traction battery pack of claim 1, wherein the flow restrictor is configured to limit flow through the pressure equalization device from 78% to 88%.

5. The traction battery pack of claim 1 , wherein the housing assembly comprises a joining section that abuts against a wall of the housing assembly and an outer section that protrudes outward from the wall, the joining section providing an inlet to the housing assembly, the outer section providing an outlet from the housing assembly, the flow restrictor being configured to limit the flow between the inlet and the outlet, and optionally, the traction battery pack further comprising a membrane retained within the housing assembly and covering the outlet.

6. The traction battery pack of claim 5, wherein the flow restrictor is configured to restrict flow to less than an amount that may flow through the outlet covered by the membrane.

7. The traction battery pack of claim 5, wherein the membrane is a water-impermeable membrane retained within the housing assembly, and optionally wherein the water-impermeable membrane is configured to allow flow to exit the pressure equalization device.

8. The traction battery pack of claim 5, wherein the current restrictor is sandwiched between the engagement section and the exterior section, and optionally wherein the engagement section is secured to the exterior section by a press fit.

9. The traction battery pack of claim 8, wherein the engagement section is mounted to the wall by a twist lock.

10. The traction battery pack of claim 1, wherein the housing assembly is dome-shaped, and further wherein the wall is part of a housing tray of the housing assembly.

11. The traction battery pack of claim 1 including a plurality of battery arrays housed within said housing assembly.

12. A traction battery pack flow control method, comprising: receiving a first flow at an inlet of the pressure equalization device, the first flow coming from inside the battery pack; limiting the first flow amount to a second flow amount that is less than the first flow amount; and The second flow mass is allowed to move through an outlet of the pressure equalization device.

13. The traction battery pack flow control method of claim 12, wherein the outlet is covered by a membrane.

14. The traction battery pack flow control method of claim 12, wherein said limiting is performed by directing said flow through an opening in a flow restrictor.

15. The traction battery pack flow control method of claim 14, wherein the current restrictor is sandwiched between the engagement section and the external section of the housing assembly.

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