Battery cooling fin and method for transferring heat energy using the cooling fin

Abstract

An exemplary battery assembly includes, among other things, a frame and a heat sink fin extending through a hole in the frame. The heat sink fin is configured to transfer thermal energy between a battery cell and a heat exchange plate. An exemplary method of transferring thermal energy within a battery pack includes, among other things, transferring thermal energy between at least one battery cell and a heat exchange plate using a heat sink fin extending through a hole in the frame.

Description

Technical Field

[0001] The present disclosure generally relates to a cooling fin within a battery array of an electrified vehicle. In particular, the present disclosure relates to a cooling fin retained within a hole of a frame. Background Art

[0002] Electrified vehicles differ from conventional motor vehicles in that they are selectively driven using one or more electric machines powered by a traction battery. The electric machines may drive the electrified vehicle in place of, or in addition to, an internal combustion engine. Exemplary electrified vehicles include hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), fuel cell vehicles (FCVs), and battery electric vehicles (BEVs).

[0003] Traction batteries for electrified vehicles typically include multiple arrays, each with individual battery cells that are periodically recharged to replenish the energy needed to power the motor. Battery cells can generate heat during charging and discharging, as well as during other operating phases. Operating battery cells at a specific temperature can improve the capacity and life of the battery cells. Summary of the invention

[0004] A battery assembly according to an exemplary aspect of the present disclosure includes, among other things, a frame and heat sink fins extending through holes in the frame. The heat sink fins are configured to transfer thermal energy between battery cells and a heat exchange plate.

[0005] In another non-limiting embodiment of the foregoing assembly, the frame is overmolded to the heat sink fins.

[0006] In another non-limiting embodiment of any of the foregoing assemblies, the frame is a polymer-based material and the heat sink fins are metal or a metal alloy.

[0007] In another non-limiting embodiment of any of the foregoing assemblies, the heat sink includes a base, a platform, and a stem extending from the base to the platform.

[0008] In another non-limiting embodiment of any of the foregoing assemblies, the platform contacts at least one battery cell on a first side of the frame, and the base is disposed on an opposing second side of the frame. A rod extends from the base through the frame to the platform.

[0009] In a further non-limiting embodiment of any of the foregoing assemblies, the base is engaged with the heat exchange plate by a thermal interface material.

[0010] In a further non-limiting embodiment of any of the foregoing assemblies, the platform contacts at least two battery cells.

[0011] In another non-limiting embodiment of any of the foregoing assemblies, the platform directly engages a vertical bottom portion of each of the at least two battery cells.

[0012] In another non-limiting embodiment of any of the foregoing assemblies, the at least two battery cells are directly engaged with each other along an engagement surface, and no portion of the heat sink fin extends between the at least two battery cells to interrupt the engagement surface.

[0013] In a further non-limiting embodiment of any of the foregoing assemblies, the at least two battery cells are adhesively secured to each other at the engaging surfaces.

[0014] In another non-limiting embodiment of any of the foregoing assemblies, the heat sink fin is a first heat sink fin, and the at least two battery cells are in direct contact with a second heat sink fin that is separate and distinct from the first heat sink fin.

[0015] In a further non-limiting embodiment of any of the foregoing assemblies, the assembly includes a subframe overmolded around the second heat sink fins.

[0016] A method of transferring thermal energy within a battery pack according to an exemplary aspect of the present disclosure includes, among other things, transferring thermal energy between at least one battery cell and a heat exchange plate using heat sink fins extending through holes in a frame.

[0017] In another non-limiting embodiment of the foregoing method, the frame is overmolded around a portion of the heat sink fin.

[0018] Another non-limiting embodiment of any of the foregoing methods includes supporting the at least one battery cell on a platform of heat sink fins.

[0019] In a further non-limiting embodiment of any of the foregoing methods, the at least one battery cell is at least two battery cells such that the platform supports more than one battery cell.

[0020] In a further non-limiting embodiment of any of the foregoing methods, a heat sink fin is engaged with a downwardly facing surface of at least one battery cell.

[0021] In another non-limiting embodiment of any of the foregoing methods, the heat sink is a first heat sink and the at least one battery cell includes a first battery cell. The method further includes transferring thermal energy from the first battery cell using the first heat sink and a second heat sink different from the first heat sink.

[0022] In a further non-limiting embodiment of any of the foregoing methods, the first heat sink fins are overmolded within a frame and the second heat sink fins are overmolded within a second frame.

[0023] 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 taken independently or in any combination. Features described in conjunction with one embodiment are applicable to all embodiments, unless such features are incompatible. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0025] FIG. 1 shows a schematic diagram of an exemplary electrified vehicle having a traction battery.

[0026] FIG. 2 illustrates a side view of the array of traction batteries from FIG. 1 , according to an exemplary embodiment of the present disclosure.

[0027] FIG. 3A shows steps in a process of assembling battery cells from the array of FIG. 2 .

[0028] FIG. 3B shows the battery cell of FIG. 3A after assembly.

[0029] FIG. 4 shows an expanded view of a selected portion of the array of FIG. 2 .

[0030] FIG. 5 shows a perspective view of the heat sink fins from the array of FIG. 2 .

[0031] 6 shows a close up cross-sectional view of the cooling fins of the traction battery from FIG. 2 , engaged with the battery cells and the heat exchange plate.

[0032] FIG. 7 illustrates a portion of an array according to another exemplary embodiment of the present disclosure.

[0033] FIG. 8 shows a cross section taken along line VIII-VIII in FIG. 7 .

[0034] FIG. 9 shows a heat dissipation fin in the prior art.

[0035] FIG. 10 illustrates the prior art heat sink fins of FIG. 9 within a selected portion of a prior art array. DETAILED DESCRIPTION

[0036] The present disclosure generally relates to a traction battery having a battery array with at least one heat sink fin. Within the battery array, the heat sink fin extends through a hole in a frame. The heat sink fin transfers heat energy between at least one battery cell and a heat exchange plate.

[0037] 1 , an exemplary electrified vehicle 10 includes a traction battery 14, an electric motor 18, and a pair of vehicle drive wheels 22. The electric motor 18 may receive power from the battery 14. The electric motor 18 converts the power into torque for the drive wheels 22. In some embodiments, the illustrated battery 14 is a relatively high voltage battery when compared to, for example, an auxiliary battery.

[0038] The exemplary vehicle 10 is a fully electric vehicle. In other examples, the electrified vehicle 10 is a hybrid electric vehicle that can selectively drive wheels 22 using torque provided by an internal combustion engine (instead of or in addition to the electric machine 18).

[0039] 2 , with continued reference to FIG1 , the battery 14 includes a plurality of battery arrays 24. Each array 24 includes a plurality of individual frames 26 and battery cells 30 disposed along an axis A. The frames 26 and battery cells 30 are axially sandwiched between end plates 34. Although the exemplary battery 14 includes a plurality of arrays 24, other exemplary batteries may include a single array.

[0040] The frame 26 and battery cells 30 are disposed adjacent to a heat exchange plate 38. The heat exchange plate 38 is used to control the thermal energy level within the battery cells 26. For example, a fluid may be circulated through channels in the heat exchange plate 38 to absorb thermal energy. The fluid may be a liquid coolant. The heated fluid is then removed from the array 24 to cool the array. The heated fluid may be moved to, for example, a liquid to air heat exchanger, where thermal energy is transferred from the heated fluid to ambient air.

[0041] 3A and 3B, the battery cell 30 of the exemplary embodiment includes an electrode structure 42 held within a housing 46. In this example, the battery cell 30 is a pouch-type lithium-ion battery cell, and the electrode structure 42 has a jelly roll (i.e., wound) configuration. In other examples, other types of battery cells may be used.

[0042] To assemble the battery cell 30, the electrode structure 42 is placed within the housing 46, which may include a first side 50 and a second side 54 connected at a hinge area 58. The first side 50 and the second side 54 are then folded around the electrode structure 42 to substantially enclose the electrode structure 42. Next, the outer edge of the first side 50 is sealed to the outer edge of the second side 54. The seam 62 extends circumferentially around the perimeter of the battery cell 30. Terminals (not shown) may extend through the seam 62 to electrically connect the electrode structure 42 to, for example, a bus bar assembly.

[0043] Generally, the hinge area 58 is considered the bottom of the battery cell 30, and the side 66 opposite the hinge area 58 is considered the top of the battery cell 30. The width W of the seam 62 along the top of the battery cell 30 is TGreater than the width W of the seam 62 along the hinge area 58 at the bottom of the battery cell 30 B The width W of the seam 62 along the lateral side of the battery cell 30 is S Greater than the width W of the seam 62 along the hinge region 58 B .

[0044] The battery cells 30 may generate heat during charging and discharging, as well as during other stages of operation.

[0045] Referring now to FIGS. 4-6 , with continued reference to FIGS. 2-3B , the array 24 utilizes heat sink fins 70 to facilitate the transfer of thermal energy between the battery cells 30 and the heat exchange plates 38 .

[0046] In the exemplary embodiment, the heat sink fins 70 each extend through an aperture 74 in an associated frame 26. The exemplary heat sink fins 70 each include a base 78, a platform 82, and a stem 86 extending from the base 78 to the platform 82.

[0047] The heat sink 70 can be a metal or metal alloy material to facilitate the transfer of thermal energy. In a specific embodiment, the heat sink 70 is aluminum. Several processes can be used to manufacture the heat sink 70. In a specific example, the heat sink 70 is extruded, which can reduce the cost and complexity of manufacturing the heat sink 70 compared to other manufacturing processes. The thickness of the exemplary heat sink 70 is about 1 mm.

[0048] In an exemplary embodiment, the frame 26 is a polymer-based material. In order to position one of the heat sink fins 70 so that the heat sink fin 70 extends through the hole 74, the frame 26 can be overmolded around the heat sink fin 70. That is, the heat sink fin 70 can be positioned within the area of ​​the mold cavity. The material is then injected into the mold cavity to form the frame 26. The material is cured to provide the frame 26 within the mold. Once cured, the heat sink fin 70 is retained within the frame 26 so that the rod 86 extends through the hole 74 in the frame 26.

[0049] In this example, the heat sink 70 is positioned so that the platform 82 faces an opening 90 provided by the frame 26. Opposite the platform 82, the base 78 faces away from the opening 90.

[0050] When the array 24 is assembled, the battery cells 30 are engaged with the platform 82 of the heat sink 70 ( FIG. 5 ). Specifically, one of the battery cells 30 rests on the first side 94A of the platform 82, and another of the battery cells 30 rests on the second side 94B of the platform 82. The outside edges of the first side 94A and the second side 94B may be turned downward to facilitate thermal contact with the seam 62 of the hinge area 58 along the bottom of the battery cell 30. In this example, each battery cell 30 is engaged with one heat sink 70.

[0051] Moreover, in this exemplary embodiment, the heat sink 70 is positioned vertically below the battery cell 30 so that gravity pushes the battery cell 30 into contact with the platform 82. Therefore, the weight of the battery cell 30 helps maintain a firm thermal contact between the platform 82 of the heat sink 70 and the battery cell 30.

[0052] Furthermore, the heat dissipation fins 70 are vertically positioned below the battery cell 30 so that the heat dissipation fins 70 engage with the hinge region 58, which is the region where the battery cell 30 has a minimum width W. B Joining the heat sink 70 to the side of the battery cell 30 having the smallest seam 62 reduces the chance that the seam 62 will interfere with heat transfer between the battery cell 30 and the heat sink fin 70 .

[0053] For purposes of this disclosure, vertical and horizontal are referenced to the ground or the normal orientation of array 24 during operation of vehicle 10 .

[0054] In another embodiment, the smallest seam 62 is located at the vertical top of the battery cell 30 and the heat sink fins 70 are repositioned to reside in the vertical top of the frame 26 so that the heat sink fins 70 can engage the side of the battery cell 30 having the smallest seam 62 .

[0055] The base 78, located outside the outer perimeter of the frame 26, thermally engages the heat exchange plate 38. A layer of thermal interface material (TIM) 96 may be used to enhance thermal conductivity at the interface between the base 48 and the heat exchange plate 38.

[0056] In an exemplary embodiment, heat energy from the battery cells 30 may move from the battery cells 30 to the platform 82, which cools the battery cells 30. The heat energy then moves through the rods 86 to the base 78. The heat energy moves from the base 78 through the TIM 96 to the heat exchange plate 38.

[0057] The fluid within the channels of the heat exchange plates 38 then heats up and is transported away from the heat exchange plates 38 .

[0058] Within the array 24, the battery cells 30 are connected to each other at axial engagement surfaces 98. An adhesive, such as tape, may be used at the axial engagement surfaces 98 to secure axially adjacent battery cells 30 to each other.

[0059] In the prior art, the heat sink fins T extend between the axial engagement surfaces of the battery cells BC, as shown in Figures 9 and 10. Therefore, a region of the heat sink fins T of the prior art is sandwiched between the battery cells BC. The heat sink fins T of the prior art are stamped, not extruded.

[0060] 3-6, however, no portion of the heat sink fins 70 extends into the region of the engagement surface 98. This can, among other things, reduce the overall axial length of the array 24 when compared to prior art arrays having heat sink fins.

[0061] In the present disclosure, the same reference numerals denote the same elements where appropriate, and reference numerals to which one hundred or multiples thereof are added denote modified elements. Unless otherwise specified, the modified elements contain the same features and benefits of the corresponding modified elements.

[0062] Referring now to FIGS. 7 and 8 , a portion of an array according to another exemplary embodiment includes a main frame 126P and a sub-frame 126S. A heat sink 170P extends through holes 174P in one main frame 126P. A heat sink 170S extends through holes 174S in one sub-frame 126S. The main frame 126P may be overmolded to the heat sink 170P, and the sub-frame 126S may be overmolded to the heat sink 170S.

[0063] At least some of the battery cells 30 held by the main frame 126P and the subframe 126S are supported on the platforms 56 of the heat sink 170P and the second heat sink 170S. In the embodiment of Figures 7 and 8, the battery cells 30 can therefore transfer thermal energy to the heat exchange plate 38 through more than one heat sink.

[0064] The first axially facing side 198A of the battery cell 30 may be directly engaged with the axially facing side of the axially adjacent battery cell and fixed to the axially adjacent battery cell by using an adhesive.

[0065] The opposing axially facing sides 198B of the battery cells 30 may be engaged with the axially adjacent battery cells 30 by the foam members 99. The foam members 99 may urge the battery cells 30 axially toward each other at the interface 172A.

[0066] Some features of the disclosed embodiments may include heat sink fins that are relatively reduced in size compared to other types of cooling fins because the cooling fins do not extend between axially facing surfaces of the battery cells.

[0067] In some specific examples where the battery array includes 32 battery cells, the use of cooling fins in the embodiments of FIGS. 2 to 5 can reduce the overall weight of the array by about 1.4 kilograms. The reduction can be attributed to the reduced weight of the heat sink fins 70, which can weigh about 29 grams. This reduction is when the battery array is compared to a battery array using prior art heat sink fins TC, which extend from the bottom of the battery cell to the top of the battery cell, as shown in FIGS. 9 and 10. The prior art heat sink fins TC can weigh about 121 grams.

[0068] If the embodiment of FIGS. 6 and 7 is utilized, the weight reduction may be approximately 0.9 kilograms for an array including 32 battery cells when compared to an array using the prior art heat sink fins TC of FIGS. 9 and 10 .

[0069] 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 such changes and modifications do not necessarily depart from the essence of the present disclosure. Therefore, the scope of legal protection afforded to the present disclosure can only be determined by studying the appended claims.

[0070] According to the present invention, a battery assembly is provided, the battery assembly having a frame; and heat sink fins extending through holes in the frame, the heat sink fins being configured to transfer thermal energy between battery cells and a heat exchange plate.

[0071] According to one embodiment, the frame is overmolded to the heat sink fins.

[0072] According to one embodiment, the frame is a polymer based material and the heat sink fins are metal or a metal alloy.

[0073] According to one embodiment, a heat sink fin includes a base, a platform, and a rod extending from the base to the platform.

[0074] According to one embodiment, the platform contacts at least one battery cell on a first side of the frame, and the base is disposed on an opposing second side of the frame, the rod extending from the base through a hole in the frame to the platform.

[0075] According to one embodiment, the base is joined to the heat exchange plate by a thermal interface material.

[0076] According to one embodiment, the platform contacts at least two battery cells.

[0077] According to one embodiment, the platform directly engages a vertical bottom portion of each of the at least two battery cells.

[0078] According to one embodiment, at least two battery cells are directly joined to each other along a joining surface, and no portion of the heat sink fin extends between the at least two battery cells to interrupt the joining surface.

[0079] According to one embodiment, at least two battery cells are adhesively fixed to each other at the joining surfaces.

[0080] According to one embodiment, the heat dissipation fin is a first heat dissipation fin, and the at least two battery cells directly contact a second heat dissipation fin that is separate and different from the first heat dissipation fin.

[0081] According to one embodiment, the above invention is further characterized by a sub-frame overmolded around the second heat sink fins.

[0082] According to one embodiment, a method of transferring thermal energy within a battery pack includes transferring thermal energy between at least one battery cell and a heat exchange plate using heat sink fins extending through holes in a frame.

[0083] According to one embodiment, the frame is overmolded around a portion of the heat sink fin.

[0084] According to one embodiment, the above invention is further characterized in that at least one battery cell is supported on a platform of heat dissipation fins.

[0085] According to one embodiment, the at least one battery unit is at least two battery units, such that the platform supports more than one battery unit.

[0086] According to one embodiment, the heat sink fins engage a downwardly facing surface of at least one battery cell.

[0087] According to one embodiment, the heat sink fin is a first heat sink fin, and the at least one battery cell includes a first battery cell, and further comprising transferring heat energy from the first battery cell using the first heat sink fin and a second heat sink fin different from the first heat sink fin.

[0088] According to one embodiment, the first heat sink fins are overmolded within a frame and the second heat sink fins are overmolded within a second frame.

Claims

1. A battery assembly, comprising: frame; as well as heat sink fins extending through the apertures in the frame, the heat sink fins being configured to transfer thermal energy between the battery cells and the heat exchange plate; wherein the heat dissipation fin comprises a base, a platform and a rod extending from the base to the platform, the platform contacts at least one battery cell on a first side of the frame, and the base is disposed on an opposite second side of the frame, the rod extending from the base through the hole of the frame to the platform; The platform is directly engaged with a vertical bottom portion of each of the at least two battery cells. 2 . The assembly of claim 1 , wherein the frame is overmolded to the heat sink fins.

3. The assembly of claim 1, wherein the frame is a polymer-based material and the heat sink fins are a metal or a metal alloy.

4. The assembly of claim 1 wherein the base is coupled to the heat exchange plate via a thermal interface material. 5 . The assembly of claim 1 , wherein the at least two battery cells are directly engaged with each other along an engagement surface and no portion of the heat sink fin extends between the at least two battery cells to interrupt the engagement surface. 6 . The assembly of claim 5 , wherein the at least two battery cells are adhesively secured to each other at the engaging surface.

7. The assembly of claim 1, wherein the heat sink fin is a first heat sink fin, and the at least two battery cells directly contact a second heat sink fin that is separate and distinct from the first heat sink fin, the assembly further comprising a subframe overmolded around the second heat sink fin.

8. A method for transferring heat energy within a battery pack, comprising: transferring thermal energy between the at least one battery cell and the heat exchange plate using heat sink fins extending through holes in the frame; wherein the heat dissipation fin comprises a base, a platform and a rod extending from the base to the platform, the platform contacts at least one battery cell on a first side of the frame, and the base is disposed on an opposite second side of the frame, the rod extending from the base through the hole of the frame to the platform; The platform is directly engaged with a vertical bottom portion of each of the at least two battery cells.

9. The method of claim 8, wherein the frame is overmolded around a portion of the heat sink fin.

10. The method of claim 8, further comprising supporting the at least two battery cells on a platform of the heat sink fins, wherein the heat sink fins engage downwardly facing surfaces of the at least two battery cells.

11. The method of claim 8, wherein the heat sink fin is a first heat sink fin and the at least one battery cell comprises a first battery cell, and the method further comprises transferring thermal energy from the first battery cell using the first heat sink fin and a second heat sink fin different from the first heat sink fin, wherein the first heat sink fin is overmolded within the frame and the second heat sink fin is overmolded within a second frame.

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