Spring retainer for pressure equalization device of traction battery pack

Abstract

The invention provides a spring retainer for a pressure equalizing device of a traction battery pack. A traction battery pack may include an outer housing assembly. A traction battery pack may include a pressure equalization device received within a wall of an outer housing assembly. The pressure equalization device may include a housing and a valve configured to close a gas path through the housing during a battery thermal event of the traction battery pack. The valve may include a spring configured to urge the valve to close during a battery thermal event. The spring is held in place by the spring holder. The spring retainer includes a first set of openings spaced apart from the spring by a first distance, and a second set of openings spaced apart from the spring by a second distance less than the first distance.

Description

Technical Field

[0001] The present disclosure relates to a spring retainer for a pressure equalization device of a traction battery pack of an electrified vehicle. Background Art

[0002] The need to reduce automotive fuel consumption and emissions is well known. As a result, vehicles are being developed that reduce or completely eliminate reliance on internal combustion engines. Electrified vehicles are one type of vehicle being developed for this purpose. Generally, electrified vehicles differ from conventional motor vehicles in that electrified vehicles are selectively driven by an electric motor powered by a battery. In contrast, conventional motor vehicles rely entirely on an internal combustion engine to propel the vehicle.

[0003] A high voltage traction battery pack typically supplies power to 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 inside an outer housing assembly to support the electric propulsion of the vehicle. The outer housing assembly must be sealed and ventilated to prevent moisture from accumulating within the interior of the battery pack. Temperature fluctuations within the battery pack can create a pressure differential between the interior of the battery and the atmosphere surrounding it. Summary of the invention

[0004] In some aspects, the technology described herein relates to a traction battery pack, comprising: an outer housing assembly; and a pressure equalization device received within a wall of the outer housing assembly, wherein the pressure equalization device comprises an outer housing and a valve, the valve being configured to close a gas path through the outer housing during a battery thermal event of the traction battery pack, wherein the valve comprises a spring, the spring being configured to urge the valve closed during the battery thermal event, wherein the spring is held in place by a spring retainer, wherein the spring retainer comprises a first set of openings spaced a first distance from the spring, and a second set of openings spaced a second distance from the spring that is less than the first distance.

[0005] In some aspects, the technology described herein relates to a traction battery pack in which a spring retainer includes a wall in contact with a first end of the spring.

[0006] In some aspects, the technology described herein is directed to a traction battery pack wherein: the spring retainer includes a ring between the first set of openings and the second set of openings, and the ring is axially spaced from the wall.

[0007] In some aspects, the technology described herein relates to a traction battery pack in which a ring is continuous around the entire circumference of the ring.

[0008] In some aspects, the technology described herein relates to a traction battery pack, wherein: a spring retainer includes a plurality of first legs that are circumferentially spaced apart from each other by corresponding openings in a first set of openings, and the spring retainer includes a plurality of second legs that are circumferentially spaced apart from each other by corresponding openings in a second set of openings.

[0009] In some aspects, the technology described herein relates to a traction battery pack wherein: a first leg protrudes between a ring and an outer ring of a spring retainer, and a second leg protrudes between the ring and a wall.

[0010] In some aspects, the technology described herein relates to a traction battery pack wherein a first leg exhibits a width dimension that tapers as it moves radially inward.

[0011] In some aspects, the technology described herein relates to a traction battery pack wherein the second leg exhibits a width dimension that tapers as it moves radially inward.

[0012] In some aspects, the technology described herein relates to a traction battery pack wherein: the first leg lies in a plane substantially perpendicular to a central axis of the valve, and the second leg protrudes from the ring to the wall in both an axial direction and a radial direction.

[0013] In some aspects, the technology described herein relates to a traction battery pack in which the second leg is curved such that the second leg is convex when viewed from a point adjacent to the piston in contact with the spring.

[0014] In some aspects, the technology described herein relates to a traction battery pack in which a first set of openings and a second set of openings are different shapes.

[0015] In some aspects, the technology described herein relates to a traction battery pack in which the second set of openings are circular when viewed from a point adjacent to the piston in contact with the spring.

[0016] In some aspects, the technology described herein relates to a traction battery pack wherein: a second end of the spring contacts the piston, the second end is opposite the first end, and during a battery thermal event, the spring is configured to move the piston in a direction opposite to the spring retainer to close the valve.

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

[0018] In some aspects, the technology described herein relates to a traction battery pack in which a spring is made of a shape memory alloy.

[0019] In some aspects, the technology described herein relates to a pressure equalization device for a traction battery pack, the pressure equalization device comprising: a housing; and a valve configured to close a gas path through the housing during a battery thermal event of the traction battery pack, wherein the valve comprises a spring configured to urge the valve closed during the battery thermal event, wherein the spring is held in place by a spring retainer, wherein the spring retainer comprises a first set of openings spaced a first distance from the spring, and a second set of openings spaced a second distance from the spring less than the first distance.

[0020] In some aspects, the technology described herein relates to a pressure equalization device wherein: a spring retainer includes a wall in contact with a first end of a spring, the spring retainer includes a ring between a first set of openings and a second set of openings, and the ring is axially spaced from the wall.

[0021] In some aspects, the technology described herein relates to a pressure equalization device wherein: a spring retainer includes a plurality of first legs, the plurality of first legs being circumferentially spaced apart from each other by corresponding openings in a first set of openings, and the spring retainer includes a plurality of second legs, the plurality of second legs being circumferentially spaced apart from each other by corresponding openings in a second set of openings.

[0022] In some aspects, the technology described herein relates to a pressure equalization device in which a first leg protrudes between a ring and an outer ring of a spring retainer, and a second leg protrudes between the ring and a wall.

[0023] In some aspects, the technology described herein relates to a pressure equalization device wherein: a first leg lies in a plane perpendicular to a central axis of the valve, a second leg protrudes from a ring to a wall in both an axial direction and a radial direction, and the second leg is bent such that the second leg is convex when viewed from a point adjacent to a piston in contact with a spring. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0025] Figure 2 is 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 A cross-sectional view of section 4-4 of FIG. 4 and illustrating features associated with a pressure equalization device for a traction battery pack. Figure 4 The valve of the pressure equalization device is in the open position.

[0028] Figure 5is similar to Figure 4 View of the pressure equalization device with the valve in the closed position.

[0029] Figure 6 It is a top view of a first embodiment of a spring retainer of a valve of a pressure equalization device.

[0030] Figure 7 is a top view of a second embodiment of a spring retainer. DETAILED DESCRIPTION

[0031] The present disclosure relates to a spring retainer for a pressure equalization device of a traction battery pack of an electrified vehicle. In addition to other benefits that will be understood from the following description, the present disclosure directs additional fluid to the spring, which reduces the time to close the valve of the pressure equalization device.

[0032] Figure 1 An electrified vehicle 10 is schematically shown. The electrified vehicle 10 may include any type of electrified powertrain. In one 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.

[0033] 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 illustrations 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.

[0034] 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 the assistance of 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.

[0035] 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.

[0036] The battery cells 26 may be stacked side by side along a stacking axis to form 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 in a direction into the page to construct each battery array 20 , and thus the battery array 20 extends in a transverse direction of the vehicle. However, other configurations are possible.

[0037] 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 one 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.

[0038] 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.

[0039] The outer housing assembly 24 can house each battery array 20 of the traction battery pack 18. The outer housing assembly 24 can be a sealed housing and can embody any size, shape, and configuration within the scope of the present disclosure. In one embodiment, the outer 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 housing 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.).

[0040] During assembly of the traction battery pack 18, the case cover 28 may be secured to the case 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 case cover 28 to the case tray 30, although other fastening methods (adhesion, etc.) may also be suitable for this purpose.

[0041] Reference now Figure 2 , 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.

[0042] Each pressure equalization device 36 can be disposed within a wall 38 of the outer 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 ). However, the exact mounting location of each pressure equalization device 36 may vary and is therefore not intended to limit the present disclosure.

[0043] The pressure equalizing devices 36 may be secured to the wall 38 in any manner. In one embodiment, each pressure equalizing device 36 is secured within the wall 38 via a quarter-turn mount. However, the pressure equalizing devices 36 may alternatively or additionally be mounted via mechanical fasteners, cam locks, adhesives, or the like.

[0044] Each pressure equalization device 36 may be configured to provide pressure equalization 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 device 36 may allow gas (e.g., air) to flow into and out of the outer housing assembly 24 while preventing moisture, particulate contaminants, etc. from entering the interior I of the traction battery pack 18.

[0045] There may be some operating conditions where it is undesirable for gases to escape through the pressure equalization device 36. 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. If allowed to escape through the pressure equalization device 36, the battery ventilation byproducts may penetrate into undesirable areas of the vehicle. Therefore, the present disclosure is directed to a pressure equalization device that is capable of providing pressure equalization during normal battery operation and preventing battery ventilation byproducts from escaping the traction battery pack 18 through the pressure equalization device during a battery thermal event.

[0046] Figure 4 A cross section of an exemplary pressure equalization device 36 is shown. In this example, the pressure equalization device 36 includes a housing 40, a water-impermeable membrane 42, and an integrated valve 44. The housing 40 includes an inner bore 46, and each of the water-impermeable membrane 42 and the valve 44 may be received within a different section of the inner bore 46.

[0047] Housing 40 may be a plastic component or a metal component and may include a single-piece structure or a multi-piece structure. The size and shape of housing 40 are not intended to be limiting of the present disclosure.

[0048] The housing 40 is oriented along a central axis Z. The valve 44 is also oriented along the central axis Z. In this embodiment, the valve 44 includes a spring 48 , a spring retainer 50 , and a piston 52 .

[0049] A first end 54 of the spring 48 contacts the spring retainer 50, and a second end 56 of the spring 48 contacts the piston 52. The piston 52 is a solid structure without any openings and is configured to seal a portion of the hole 46 of the housing 40 directly or via an intermediate structure such as a seal or gasket to close the valve 44 and prevent fluid from flowing in or out through the pressure equalization device 36. The piston 52 is centered and biased to the position by the spring 53. Figure 4 The valve 44 is in the open position. Figure 5 is shown in the closed position. Figure 5 As shown, the piston 52 directly or indirectly contacts and seals a portion of the hole 46 of the housing 40 to prevent fluid from flowing in or out. Figure 5 In the embodiment, the force of spring 48 has overcome the force of spring 53, so that piston 52 is relative to Figure 4 and Figure 5 Move vertically upward to create a seal.

[0050] Although a spring 48 is shown in this embodiment, in other examples, the spring 48 may be replaced with another type of actuation device.

[0051] In the present disclosure, the spring 48 is made of a shape memory alloy material. Specifically, when a relatively high temperature is applied to the spring 48, the spring 48 is configured to rebound to a rebound shape to move the piston 52 in a direction opposite to the spring retainer 50 to close the valve 44. In one example, the spring 48 rebounds to the rebound shape during a battery thermal event.

[0052] As an example, spring 48 may be made of any known SMA material, such as copper-aluminum-nickel and nickel-titanium (NiTi) alloys. The present disclosure extends to other SMA materials, including but not limited to materials produced by alloying zinc, copper, gold, and iron. Although shape memory alloys are mentioned, spring 48 may be made of other materials that expand sufficiently to close valve 44 when exposed to heat.

[0053] Figure 6 Additional details of one embodiment of a spring retainer 50 according to one aspect of the present disclosure are shown. The spring 48 is Figure 6 Shown in for reference. Figure 6 From the perspective of a point adjacent to the piston 52 (i.e., relative to Figure 4 and Figure 5 , the spring retainer 50 is shown from a perspective vertically above the spring retainer 50 ).

[0054] Moving radially outward to inward (the term "radial" is used with reference to the central axis Z), the spring retainer 50 includes an outer ring 58. The outer ring 58 is continuous around the entire central axis Z. In this example, the outer ring 58 is fixedly mounted to the housing 40. Radially inward of the outer ring 58, the spring retainer 50 includes a first set of openings 60 that are circumferentially spaced from each other by first legs 62. In this example, the first legs 62 exhibit a width W1 that tapers as they move radially inward. In this example, there are three first legs 62 and three openings 60 in the first set. The present disclosure is not limited to a specific number of first legs 62 or openings 60.

[0055] The first leg 62 projects from the outer ring 58 to the inner ring 64 . The inner ring 64 is continuous around the entire central axis Z. In this example, the outer ring 58 , the first leg 62 and the inner ring 64 are all located in a common plane that is substantially perpendicular to the central axis Z.

[0056] Moving inward from the inner ring 64, the spring retainer 50 includes a second set of openings 66 that are circumferentially spaced apart from each other by second legs 68. In this example, the second legs 68 exhibit a width W2 that tapers as they move radially inward. In this example, there are six second legs 68 and six openings 66 in the second set. The present disclosure is not limited to a particular number of second legs 68 or openings 66.

[0057] The second set of openings 66 is spaced a smaller distance, specifically a smaller radial distance, from the spring 48 and the center axis Z than the first set of openings 60. In this manner, fluid flowing through the second set of openings 66 is more likely to flow closer to the spring 48 and interact directly with the spring. Thus, during a battery thermal event, the spring 48 is configured to return to a resilient shape more quickly than if the second set of openings 66 were not present.

[0058] The second set of legs 68 protrude from the inner ring 64 in both the radial direction and the axial direction toward the center axis Z. Specifically, the second set of legs 68 is away from the piston 52 (relative to the inner ring 64). Figure 6 The second set of legs 68 is convex when viewed from a point adjacent to the piston 52, such as Figure 4 . The wall 70 lies in a plane that is substantially perpendicular to the central axis Z and substantially parallel to a common plane containing the outer ring 58, the first set of legs 62, and the inner ring 64. The wall 70 provides the bottom of the recess for retaining the spring 48. The wall 70 may have a central opening to allow additional fluid to flow relative to the spring 48.

[0059] Although the second set of openings 66 is Figure 6, which substantially matches the shape of the first set of openings 60, but the present disclosure is not limited to the specific shape of the second set of openings 66. Figure 7 As shown, for example, when viewed from a point adjacent to the piston 52, the second set of openings 66 can be circular. In other embodiments, the shape of the openings 66 can be different from Figure 6 and Figure 7 The shapes shown in , such as triangles. Figure 7 , the second leg 68 exhibits a contour corresponding to the adjacent opening 66 and is generally hourglass-shaped.

[0060] It should be understood that terms such as "about," "substantially," and "substantially" are not intended to be open-ended terms, and should be interpreted consistently with the manner in which those skilled in the art would interpret those terms.

[0061] Although different examples have specific components shown in the drawings, embodiments of the present disclosure are not limited to those specific combinations. Some of the components or features from one of the examples may be used in combination with features or components from another of the examples. In addition, the various drawings of the present disclosure are not necessarily drawn to scale, and some features may be enlarged or minimized to show certain details of a particular component or arrangement.

[0062] Those skilled in the art will appreciate that the above embodiments are exemplary and not restrictive. That is, modifications of the present disclosure will fall within the scope of the claims. Therefore, the appended claims should be studied to determine their true scope and content.

[0063] According to the present invention, a pressure equalization device for a traction battery pack is provided, the pressure equalization device having: a housing; and a valve, the valve being configured to close a gas path through the housing during a battery thermal event of the traction battery pack, wherein the valve comprises a spring, the spring being configured to urge the valve closed during the battery thermal event, wherein the spring is held in place by a spring retainer, wherein the spring retainer comprises a first set of openings spaced a first distance from the spring, and a second set of openings spaced a second distance from the spring that is less than the first distance.

[0064] According to one embodiment, the spring retainer includes a wall in contact with the first end of the spring, the spring retainer includes a ring between the first set of openings and the second set of openings, and the ring is axially spaced from the wall.

[0065] According to one embodiment, the spring retainer includes a plurality of first legs, which are circumferentially spaced apart from each other by corresponding openings in the first set of openings, and the spring retainer includes a plurality of second legs, which are circumferentially spaced apart from each other by corresponding openings in the second set of openings.

[0066] According to one embodiment, the first leg protrudes between the ring and the outer ring of the spring retainer and the second leg protrudes between the ring and the wall.

[0067] According to one embodiment, the first leg lies in a plane perpendicular to the central axis of the valve, the second leg protrudes from the ring to the wall in both axial and radial directions, and the second leg is curved so that the second leg is convex when viewed from a point adjacent to the piston in contact with the spring.

Claims

1. A traction battery pack, comprising: Outer shell assembly; as well as a pressure equalizing device received within a wall of the outer housing assembly, The pressure equalization device includes a housing and a valve, the valve being configured to close a gas path through the housing during a battery thermal event of the traction battery pack, wherein the valve includes a spring, the spring being configured to urge the valve closed during the battery thermal event, wherein the spring is held in place by a spring retainer, wherein the spring retainer includes a first set of openings spaced a first distance from the spring, and a second set of openings spaced a second distance from the spring that is less than the first distance. 2 . The traction battery pack of claim 1 , wherein the spring retainer includes a wall in contact with the first end of the spring.

3. The traction battery pack according to claim 2, wherein: The spring retainer includes a ring between the first set of openings and the second set of openings, and The ring is axially spaced from the wall.

4. The traction battery pack of claim 3, wherein the ring is continuous around the entire circumference of the ring.

5. The traction battery pack according to claim 3, wherein: The spring retainer includes a plurality of first legs circumferentially spaced apart from one another by respective ones of the first set of openings, and The spring retainer includes a plurality of second legs circumferentially spaced apart from one another by respective ones of the second set of openings.

6. The traction battery pack according to claim 5, wherein: The first leg protrudes between the ring and the outer ring of the spring retainer, and The second leg protrudes between the ring and the wall.

7. The traction battery pack of claim 5, wherein the first leg exhibits a width dimension that tapers as it moves radially inward.

8. The traction battery pack of claim 7, wherein the second leg exhibits a width dimension that tapers as it moves radially inward.

9. The traction battery pack according to claim 5, wherein: The first leg lies in a plane substantially perpendicular to a central axis of the valve, and The second legs protrude from the ring to the wall in both axial and radial directions.

10. The traction battery pack of claim 9, wherein the second leg is curved such that the second leg is convex when viewed from a point adjacent to the piston in contact with the spring.

11. The traction battery pack of claim 1 , wherein the first set of openings and the second set of openings are different shapes.

12. The traction battery pack of claim 11, wherein the second set of openings are circular when viewed from a point adjacent to the piston in contact with the spring.

13. The traction battery pack according to claim 2, wherein: The second end of the spring is in contact with the piston, The second end is opposite to the first end, and During the battery thermal event, the spring is configured to move the piston in a direction opposite to the spring retainer to close the valve.

14. The traction battery pack of claim 1, comprising a plurality of battery arrays housed within the outer housing assembly.

15. The traction battery pack of claim 1, wherein the spring is made of a shape memory alloy.

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