Traction battery pack thermal management system and thermal management method

Abstract

The invention discloses a traction battery pack thermal management system and a thermal management method. A traction battery pack comprising: a stack of cells; the shell assembly is used for accommodating the battery cell stack; and a leg separating the stack of cells from a portion of the housing assembly to provide a coolant channel configured to convey a coolant. The foot may be part of the housing assembly or part of an insert separate from the housing assembly.

Description

Technical Field

[0001] The present disclosure generally relates to managing thermal energy within a battery pack. Background Art

[0002] An electrified vehicle differs from a conventional motor vehicle in that an electrified vehicle includes a drive train having one or more electric machines. The electric machines may drive the electrified vehicle as an alternative to or in addition to an internal combustion engine. A traction battery pack assembly may power the electric machines. A coolant may be moved through the traction battery pack to help manage heat within the traction battery pack. Summary of the invention

[0003] In some aspects, the technology described herein relates to a traction battery pack comprising: a cell stack; a housing assembly that houses the cell stack; and a plurality of legs that separate the cell stack from a portion of the housing assembly to provide a coolant channel configured to convey a coolant.

[0004] In some aspects, the technology described herein relates to a traction battery pack wherein the coolant is a non-conductive coolant.

[0005] In some aspects, the technology described herein relates to a traction battery pack wherein the plurality of legs are part of the housing assembly.

[0006] In some aspects, the technology described herein relates to a traction battery pack wherein the housing assembly is a metal or metal alloy. In another example, the housing assembly is a polymer-based material.

[0007] In some aspects, the technology described herein relates to a traction battery pack, further comprising: an insert providing the plurality of legs, the insert being separate from the housing assembly.

[0008] In some aspects, the technology described herein relates to a traction battery pack wherein the coolant passage opens into the battery cell stack such that coolant passing through the coolant passage directly contacts the battery cell stack.

[0009] In some aspects, the technology described herein relates to a traction battery pack wherein the coolant channels are part of an immersion system for thermal management of the battery cell stack.

[0010] In some aspects, the technology described herein relates to a traction battery pack wherein the coolant is a liquid coolant.

[0011] In some aspects, the technology described herein relates to a traction battery pack wherein the housing assembly includes a tray and a cover, the housing tray includes a bottom wall, wherein at least some of the plurality of legs extend from the bottom wall to the cell stack.

[0012] In some aspects, the technology described herein relates to a traction battery pack wherein the housing assembly includes a first side wall, a second side wall opposite the first side wall, a first end wall, and a second end wall opposite the first end wall.

[0013] In some aspects, the technology described herein relates to a traction battery pack wherein the housing cover includes a top wall wherein at least some of the plurality of legs extend from the top wall to the cell stack such that the cell stack is spaced apart from the bottom wall and from the top wall.

[0014] In some aspects, the technology described herein relates to a traction battery pack, wherein the housing assembly includes a first side wall, a second side wall opposite the first side wall, a first end wall, and a second end wall opposite the first end wall, wherein the plurality of legs are arranged in a row, and the row is angled relative to the first side wall, the second side wall, the first end wall, and the second end wall.

[0015] In some aspects, the technology described herein relates to a traction battery pack wherein the row includes legs having a first length and legs having a second length different than the first length.

[0016] In some aspects, the technology described herein relates to a traction battery pack, wherein the housing assembly includes a first side wall, a second side wall opposite the first side wall, a first end wall, and a second end wall opposite the first end wall, wherein the plurality of legs are arranged parallel to the first end wall and parallel to the second end wall.

[0017] In some aspects, the technology described herein relates to a method of managing coolant, comprising: using a plurality of legs to separate a battery cell stack from a portion of a housing assembly, the separation providing a coolant channel; and directing coolant through the coolant channel to manage thermal energy within the battery cell stack.

[0018] In some aspects, the technology described herein relates to a method, further comprising: immersion cooling the battery cell stack using the coolant.

[0019] In some aspects, the technology described herein relates to a method wherein the plurality of legs are part of the housing.

[0020] In some aspects, the technology described herein relates to a method wherein the plurality of legs are stamped into the housing.

[0021] In some aspects, the technology described herein is directed to a method wherein the battery cell stack is sandwiched between legs extending downwardly from a top wall of a housing cover and legs extending upwardly from a bottom wall of a housing tray.

[0022] In some aspects, the technology described herein relates to a method in which the coolant reservoir is part of an immersion thermal management system.

[0023] The embodiments, examples and alternatives of the preceding paragraphs, 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 conjunction with one embodiment apply to all embodiments, unless such features are incompatible. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] According to the detailed description, various features and advantages of the disclosed examples will become apparent to those skilled in the art. The drawings attached to the detailed description can be briefly described as follows:

[0025] Figure 1 A side view of an electrified vehicle with a traction battery pack is shown.

[0026] Figure 2 Shows Figure 1 A perspective view of the traction battery pack.

[0027] Figure 3 Shown along Figure 2 A cross-sectional view taken along line 3-3 in FIG.

[0028] Figure 4 Shows Figure 3 Close-up view of the area.

[0029] Figure 5 Shows Figures 2 to 4 View of the underside of the housing cover of a traction battery pack.

[0030] Figure 6 A cross-sectional view of a traction battery pack according to another exemplary aspect of the present disclosure is shown.

[0031] Figure 7 Shows Figure 6 Close-up view of the area.

[0032] Figure 8 Shows Figure 6 and Figure 7 View of the underside of the housing cover of a traction battery pack. DETAILED DESCRIPTION

[0033] An immersion thermal management system may be used to manage thermal energy in a battery pack. When using such a system, components such as battery cells may be at least partially immersed in a coolant circulating through a traction battery pack. This disclosure details exemplary methods and systems for managing coolant flow within a traction battery pack.

[0034] refer to Figure 1 , the electrified vehicle 10 includes a traction battery pack 14, an electric motor 18, and wheels 22. The traction battery pack 14 provides power to the electric motor 18, which can convert the electricity into mechanical power to drive the wheels 22. The traction battery pack 14 can be a relatively high voltage battery.

[0035] In the exemplary embodiment, the traction battery pack 14 is secured to an underbody 26 of the electrified vehicle 10. In other examples, the traction battery pack 14 may be located elsewhere on the electrified vehicle 10.

[0036] 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 or supplement to an electric machine) to drive wheels. In general, the electrified vehicle 10 can be any type of vehicle having a traction battery pack.

[0037] Reference now Figures 2 to 5 , the traction battery pack 14 includes a cell stack 30 housed within a housing assembly 34. Each of the cell stacks 30 may include a plurality of individual battery cells.

[0038] A plurality of battery cells (or simply “cells”) are used to supply power to the various components of the electrified vehicle 10 . The battery cells are stacked side-by-side relative to one another to provide a cell stack 30 .

[0039] In an exemplary embodiment, the housing assembly 34 includes a housing cover 38 and a housing tray 42. In one example of the present disclosure, the housing cover 38 can be bolted to the housing tray 42. In other examples, the housing cover 38 and the housing tray 42 can be connected using other fluid-tight connection techniques (such as adhesives or welding). In addition, although an exemplary housing assembly 34 is shown, the size, shape, and configuration of the housing assembly 34 can vary within the scope of the present disclosure.

[0040] The housing cover 38 is secured to the housing tray 42 to provide an interior area 46 that houses the cell stacks 30. The traction battery pack 14 includes two cell stacks 30 located within the interior area 46 of the housing assembly 34. Other components such as bus bars, insulators, control modules, etc. may additionally be housed within the housing assembly 34.

[0041] Although in the present disclosure Figure 2 A specific number of battery cell stacks 30 are shown in the figure, but the traction battery pack 14 may include any number of battery cells and battery cell stacks 30. In other words, the present disclosure is not limited to Figure 2 The specific configuration of the battery cells and battery cell stack 30 shown. In addition, the battery pack 14 can be combined with other battery packs 14 to provide Figure 1 A battery pack assembly for a vehicle 10 .

[0042] In this example, the battery cells within the cell stack 30 are lithium-ion pouch cells. However, within the scope of the present disclosure, battery cells having other geometries (cylindrical, etc.) and / or chemistries (nickel-metal hydride, lead acid, etc.) may alternatively be utilized.

[0043] As the vehicle 10 operates, thermal energy levels within the battery cells and the cell stack 30 may increase. The example vehicle 10 incorporates a thermal management system to manage thermal energy levels within the battery cells, the cell stack 30, and other areas of the traction battery pack 14. The thermal management system may be used to cool the battery cells of the cell stack 30. In some examples, the thermal management system may be used to heat the battery cells of the cell stack 30.

[0044] The example thermal management system delivers the coolant C to the interior region 46 of the battery pack 14 through the inlet 50. In this example, the coolant C fills all open areas within the interior region 46, so that the battery cell stack 30 is immersed in the coolant C within the battery pack 14 and in direct contact with the coolant C. Using the interior region 46, the coolant can absorb thermal energy from the battery cell stack 30 and other components of the battery pack 14.

[0045] The coolant C exits the battery pack 14 through the outlet 54. The coolant C may then move to a thermal energy exchange device, such as a heat exchanger, where thermal energy is transferred from the coolant C. A pump may be operated to circulate the coolant C between the battery pack 14 and the thermal energy exchange device.

[0046] In this example, the coolant C is a dielectric fluid. The coolant may be oil. The non-conductive coolant C may be a liquid designed for immersion cooling of the battery cell stack 30. The chemical composition and design characteristics of the coolant C (e.g., dielectric constant, maximum breakdown strength, boiling point, etc.) may vary depending on the environment in which the battery pack 14 is used.

[0047] Unlike the conductive glycol typically utilized in known cold plate systems, the coolant C received within the immersion-cooled cell stack 30 of the present disclosure allows for direct contact with the battery cells and other electrified components without causing electrical short circuits, thereby improving cooling and performance. The exemplary immersion cooling strategy further enables high-rate charging and discharging, and allows for high load requirements without increasing the hardware size of the battery array.

[0048] The battery pack 14 includes a flow management system that incorporates features that facilitate heat transfer between the coolant C and components of the battery pack 14. As an example, the battery pack includes a plurality of stand-offs 60 that are used to space the cell stack 30 from a portion 62 of the housing assembly 34 to provide a coolant channel 64 between the cell stack 30 and the portion of the housing assembly 34. As the coolant C moves from the inlet 50 to the outlet 54, the coolant C can be transmitted through the coolant channel 64 to cool the cell stack 30.

[0049] In an exemplary embodiment, the standoff 60 is part of the housing assembly 34. The housing cover 38 and the housing tray 42 can be a metal or metal alloy with a nominal thickness of three millimeters. In some examples, the standoff 60 can be considered a dimple in the housing assembly 34. The shape, orientation, size, height of the standoff 60 can be varied to provide a designed spacing for the coolant C.

[0050] The housing cover 38 and the housing tray 42 may be cast to include the feet 60. In another example, the feet 30 may be stamped. In yet another example, the feet 60 may be provided on an insert that is separate from the housing assembly 34 and assembled within the interior region 46 between the housing assembly 34 and the cell stack 30.

[0051] The housing cover 38 includes a top wall 68. Some of the legs 60 extend vertically downward from the top wall 68 to the cell stack 30. The housing tray 42 includes a bottom wall 72. Some of the legs 60 extend vertically upward from the top wall 72 to the cell stack 30. Thus, the cell stack 30 is vertically sandwiched between the legs 60 above and below the cell stack 30 and vertically spaced apart from the top wall 68 and the bottom wall 72 to establish a coolant channel above and below the cell stack 30.

[0052] The housing assembly includes a first side wall 76, a second side wall 80 opposite the first side wall 76, a first end wall 84, and a second end wall 88 opposite the first end wall 84. The housing cover 38 and the housing tray 42 each provide a portion of the first side wall 76, the second side wall 80, the first end wall 84, and the second end wall 88. In another example, the housing cover 38 or the housing tray 42 provides the first side wall 76, the second side wall 80, the first end wall 84, and the second end wall 88.

[0053] As combined Figure 5 As shown in the housing cover 38 of FIG. 1 , the plurality of legs 60 are arranged in a row 92 that is angled relative to the first side wall 76, the second side wall 80, the first end wall 84, and the second end wall 88. In this example, the row 92 is offset from the first side wall 76, the second side wall 80, the first end wall 84, and the second end wall 88 by forty-five degrees.

[0054] In this example, the legs 60 include legs 60A having a first length L1 and legs 60B having a second length L2 different from the first length. In other examples, legs having other lengths may be used.

[0055] The angle of the rows 92 , the different lengths of the legs 60 , or both may help direct the coolant C along a circuitous path, which may promote efficient heat transfer between the coolant C and different areas of the cell stack 30 .

[0056] Figure 5 The feet 60 are shown extending from the housing cover 38. The feet 60 extending from the bottom wall 72 of the housing tray 42 may be similarly arranged having angled rows and varying lengths.

[0057] Reference now Figures 6 to 8 Another example battery pack 114 includes a housing assembly 134 having a housing cover 138 and a housing tray 142. A plurality of legs 160 extend from a top wall 168 of the housing cover 138 or from a bottom wall 172 of the housing tray 142. The plurality of legs 160 are arranged parallel to the first end wall 184 and parallel to the second end wall 188. The coolant C can move above the top of the cell stack 30 and below the cell stack 30 within the space provided by the legs 160.

[0058] It should be understood that terms such as "about," "substantially," and "approximately" are not intended to be open-ended terms and should be interpreted consistent with the manner in which those skilled in the art would interpret those terms. It should also be understood that directional terms such as "upper," "top," "vertical," "forward," "rearward," "side," "above," "below," etc., are used herein with respect to the normal operating posture of the vehicle for purposes of explanation only and should not be considered limiting.

[0059] 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 accompanying 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.

[0060] The foregoing description is illustrative rather than restrictive in nature. Changes and modifications to the disclosed examples may become apparent to those skilled in the art, and the changes and modifications do not necessarily depart from the essence of the present disclosure. Therefore, the scope of protection granted to the present disclosure can only be determined by studying the attached claims.

Claims

1. A traction battery pack, comprising: Battery cell stack; A casing assembly, wherein the casing assembly accommodates the battery cell stack; as well as A plurality of legs space the cell stack apart from a portion of the housing assembly to provide a coolant passage configured to convey a coolant.

2. The traction battery pack of claim 1, wherein the coolant is a non-conductive coolant.

3. The traction battery pack of claim 1 , wherein the plurality of legs are part of the housing assembly, and optionally wherein the housing assembly is a metal or metal alloy.

4. The traction battery pack according to claim 1, further comprising: An insert for the plurality of legs is provided, the insert being separate from the housing assembly. 5 . The traction battery pack of claim 1 , wherein the coolant passage opens into the battery cell stack such that the coolant passing through the coolant passage directly contacts the battery cell stack.

6. The traction battery pack of claim 1, wherein the coolant channel is part of an immersion system for thermal management of the battery cell stack.

7. The traction battery pack of claim 1, wherein the coolant is a liquid coolant.

8. The traction battery pack of claim 1 , wherein the housing assembly comprises a tray and a cover, the tray comprising a bottom wall, wherein at least some of the plurality of legs extend from the bottom wall to the cell stack, and optionally, wherein the housing assembly comprises a first side wall, a second side wall opposite the first side wall, a first end wall, and a second end wall opposite the first end wall.

9. The traction battery pack of claim 8, wherein the housing cover includes a top wall, wherein at least some of the plurality of legs extend from the top wall to the cell stack such that the cell stack is spaced apart from the bottom wall and from the top wall.

10. The traction battery pack of claim 1, wherein the housing assembly includes a first side wall, a second side wall opposite the first side wall, a first end wall, and a second end wall opposite the first end wall, wherein the plurality of legs are arranged in a row, the row being angled relative to the first side wall, the second side wall, the first end wall, and the second end wall, and optionally wherein the row includes legs having a first length and legs having a second length different from the first length.

11. The traction battery pack of claim 1 , wherein the housing assembly comprises a first side wall, a second side wall opposite the first side wall, a first end wall, and a second end wall opposite the first end wall, wherein the plurality of legs are arranged parallel to the first end wall and parallel to the second end wall.

12. A method of managing a coolant, comprising: Using a plurality of legs to space the cell stack from a portion of the housing assembly, the spacing providing a coolant passage; as well as Coolant is directed through coolant channels to manage thermal energy within the battery cell stack.

13. The method of claim 12, further comprising: The coolant is used to immerse and cool the battery cell stack.

14. The method of claim 12, wherein the plurality of legs are part of the housing, and optionally wherein the plurality of legs are stamped into the housing.

15. The method of claim 12, wherein the battery cell stack is sandwiched between legs extending downwardly from a top wall of the housing cover and legs extending upwardly from a bottom wall of the housing tray.

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