Array plate assembly for applying compression spring force to battery cell stack

Abstract

The battery assembly includes a battery cell group and an array plate assembly contacting at least one cell of the battery cell group. The array plate assembly includes a spring plate adapted to apply a compressive spring force to the at least one cell. The compressive spring force may be based on a dimensional profile of the battery cell group.

Description

Technical Field

[0001] The present invention relates to a battery assembly for an electric vehicle battery pack. An exemplary battery assembly includes an array plate assembly for applying a compressive spring force to a battery cell group. Background Art

[0002] The desire to reduce automotive fuel consumption and emissions is well documented. As a result, vehicles are being developed that reduce or completely eliminate reliance on internal combustion engines. Electric vehicles are currently being developed for this purpose. In general, electric vehicles differ from conventional motor vehicles in that they are selectively driven by one or more battery-powered electric motors. In contrast, conventional motor vehicles rely entirely on internal combustion engines to propel the vehicle.

[0003] High voltage battery packs typically supply power to the motors and other electrical loads of electric vehicles. The battery pack includes multiple battery cells that store energy for supplying power to these electrical loads. The battery cells generate heat during charging and discharging operations. Sometimes, such as when charging the battery cells, the outer contour of the battery cells may bulge or bulge. The bulge may cause inconsistent battery stack dimensions, resulting in packaging challenges. Summary of the invention

[0004] A battery assembly according to an exemplary aspect of the invention includes, among other things, a battery cell group and an array plate assembly contacting at least one cell of the battery cell group. The array plate assembly includes a spring plate adapted to apply a compressive spring force to the at least one cell.

[0005] In another non-limiting embodiment of the foregoing battery assembly, the array plate assembly is disposed at a longitudinal extent of the battery cell group.

[0006] In another non-limiting embodiment of one of the foregoing battery assemblies, the array plate assembly is disposed along a side of the battery cell group.

[0007] In another non-limiting embodiment of any of the foregoing battery assemblies, the spring plate includes a spring member that is movable between a deployed position and a retracted position when a profile of at least one of the cells changes.

[0008] In another non-limiting embodiment of any of the foregoing battery assemblies, the profile is changeable between a first profile and a second profile that is at least partially convex relative to the first profile.

[0009] In another non-limiting embodiment of any of the foregoing battery assemblies, the spring plate includes a plate body and a spring member protruding from the plate body.

[0010] In another non-limiting embodiment of any of the foregoing battery assemblies, the battery assembly includes a second spring member protruding from the plate.

[0011] In another non-limiting embodiment of any of the foregoing battery assemblies, the array plate assembly includes an outer plate and an inner plate, and the spring plate extends between the outer plate and the inner plate.

[0012] In another non-limiting embodiment of any of the foregoing battery assemblies, the spring plate includes a contact surface adjacent to the inner plate and an outer perimeter adjacent to the outer plate.

[0013] In another non-limiting embodiment of any of the foregoing battery assemblies, the spring plate includes a spring member having a contact surface and a plurality of connecting plates.

[0014] In another non-limiting embodiment of any of the foregoing battery assemblies, at least one of the contact surface and the plurality of connection plates is flexible in response to a change in size of the battery cell group.

[0015] In another non-limiting embodiment of any of the foregoing battery assemblies, each of the plurality of connection plates extends between the contact surface and an outer perimeter of the spring plate.

[0016] In another non-limiting embodiment of any of the foregoing battery assemblies, openings are disposed between adjacent ones of the plurality of connecting plates.

[0017] In another non-limiting embodiment of any of the foregoing battery assemblies, the spring plate includes a first spring member and a second spring member adjacent to the first spring member.

[0018] In a further non-limiting embodiment of any of the foregoing battery assemblies, a central beam extends between the first spring member and the second spring member.

[0019] Among other things, a method according to another exemplary aspect of the invention includes applying a compressive spring force to a battery cell group of a battery assembly via an array plate assembly including a spring plate for applying the compressive spring force based on a dimensional profile of the battery cell group.

[0020] In another non-limiting embodiment of the foregoing method, in response to at least one cell of the battery cell group moving toward a more convex profile, the spring member of the spring plate moves toward the retracted position.

[0021] In another non-limiting embodiment of one of the foregoing methods, in response to at least one cell in the battery cell group moving toward the less convex profile, the spring member of the spring plate moves toward the deployed position.

[0022] In another non-limiting embodiment of any of the foregoing methods, the spring member of the spring plate includes a contact surface that abuts at least one cell of the battery cell group or an inner plate of the array plate assembly.

[0023] In another non-limiting embodiment of any of the foregoing methods, the spring member includes a plurality of flexible webs, and at least one of the contact surface and the plurality of flexible webs moves in response to a change in the dimensional profile to maintain the compressive spring force.

[0024] The embodiments, examples and alternatives of the preceding paragraphs, claims or the following description and drawings, including any of their various aspects or individual features, may be made independently or in any combination. Features described in conjunction with one embodiment are applicable to all embodiments, unless these features are incompatible.

[0025] The various features and advantages of the present invention 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

[0026] Figure 1 schematically illustrates a powertrain system for an electric vehicle;

[0027] Figure 2 A battery assembly for an electric vehicle is shown;

[0028] Figure 3 yes Figure 2 An exploded view of the battery assembly;

[0029] Figure 4 yes Figure 2 A cross-sectional view of a battery assembly;

[0030] Figure 5 Shows Figure 2 A battery cell of a battery assembly;

[0031] Figure 6 Another exemplary battery assembly is shown;

[0032] Figure 7 Another exemplary battery assembly is shown;

[0033] Figure 8 Yet another exemplary battery assembly is shown;

[0034] Fig. 9 Yet another exemplary battery assembly is shown;

[0035] Fig.10 is a side view of an exemplary spring plate for a battery assembly;

[0036] Fig.11 yes Fig.10 A front view of a spring plate;

[0037] Fig.12 yes Fig.10 A three-dimensional view of a spring plate;

[0038] Fig.13 Another exemplary spring plate for a battery assembly is shown. DETAILED DESCRIPTION

[0039] The present invention details a battery assembly for use in an electric vehicle battery pack. An exemplary battery assembly includes a battery cell group and an array plate assembly that contacts at least one cell of the battery cell group. The array plate assembly includes one or more spring members adapted to apply a compression spring force to the battery cell group. The compression spring force maintains a compression force on the battery cell group. The compression force ensures a more consistent battery stack size despite any battery cell thickness variations. These and other features of the present invention are discussed in more detail in the following paragraphs of this detailed description.

[0040] Figure 1 Schematically illustrated is a powertrain 10 for an electric vehicle 12. Although described as a hybrid electric vehicle (HEV), it should be understood that the concepts described herein are not limited to HEVs and may extend to other electric vehicles including, but not limited to, plug-in hybrid electric vehicles (PHEVs), battery electric vehicles (BEVs), fuel cell vehicles, etc.

[0041] In a non-limiting embodiment, the powertrain 10 is a power split powertrain using a first and a second drive system. The first drive system includes a combination of an engine 14 and a generator 18 (i.e., a first electric machine). The second drive system includes at least a motor 22 (i.e., a second electric machine), the generator 18, and a battery pack 24. In this example, the second drive system is considered to be the electric drive system of the powertrain 10. Each of the first and second drive systems is capable of generating torque to drive one or more sets of vehicle drive wheels 28 of the electric vehicle 12. Although Figure 1 A power distribution configuration is described, but the invention extends to any hybrid or electric vehicle including a full hybrid, parallel hybrid, series hybrid, mild hybrid or micro hybrid.

[0042] The engine 14, which may be an internal combustion engine, and the generator 18 may be connected via a power transfer unit 30, such as a planetary gear set. Of course, other types of power transfer units including other gear sets and transmissions may be used to connect the engine 14 to the generator 18. In a non-limiting embodiment, the power transfer unit 30 is a planetary gear set including a ring gear 32, a sun gear 34, and a planetary gear carrier assembly 36.

[0043] The generator 18 can be driven by the engine 14 through the power transfer unit 30 to convert kinetic energy into electrical energy. Alternatively, the generator 18 can function as a motor to convert electrical energy into kinetic energy, thereby outputting torque to a shaft 38 connected to the power transfer unit 30. Because the generator 18 is operatively connected to the engine 14, the speed of the engine 14 can be controlled by the generator 18.

[0044] The ring gear 32 of the power transfer unit 30 can be connected to the shaft 40 connected to the vehicle drive wheels 28 through the second power transfer unit 44. The second power transfer unit 44 may include a gear set having a plurality of gears 46. Other power transfer units may also be suitable. The gears 46 transfer the torque from the engine 14 to the differential 48 to ultimately provide traction to the vehicle drive wheels 28. The differential 48 may include a plurality of gears that enable the torque to be transferred to the vehicle drive wheels 28. In a non-limiting example, the second power transfer unit 44 is mechanically connected to the axle 50 through the differential 48 to distribute the torque to the vehicle drive wheels 28.

[0045] The motor 22 may also be used to drive the vehicle drive wheels 28 by outputting torque to a shaft 52 that is also connected to the second power transfer unit 44. In a non-limiting embodiment, the motor 22 and the generator 18 cooperate as part of a regenerative braking system in which the motor 22 and the generator 18 can be used as motors to output torque. For example, each of the motor 22 and the generator 18 can output power to the battery pack 24.

[0046] The battery pack 24 is an exemplary electric vehicle battery. The battery pack 24 may be a high voltage traction battery pack that includes a plurality of battery assemblies 25 (i.e., a battery array or battery cell group) that are capable of outputting power to operate the motor 22, the generator 18, and / or other electrical loads of the electric vehicle 12. Other types of energy storage devices and / or output devices may also be used to provide power to the electric vehicle 12.

[0047] In a non-limiting embodiment, the electric vehicle 12 has two basic operating modes. The electric vehicle 12 can be operated in an electric vehicle (EV) mode, in which the motor 22 is used for vehicle propulsion (typically without assistance from the engine 14), thereby depleting the battery pack 24 state of charge until its maximum allowable discharge rate under a particular driving mode / cycle. The EV mode is an example of a charge-depleting operating mode of the electric vehicle 12. During the EV mode, the state of charge of the battery pack 24 can increase under certain circumstances, such as due to a period of regenerative braking. The engine 14 is generally turned off (OFF) in the default EV mode, but can be operated when necessary based on vehicle system conditions or as permitted by the operator.

[0048] The electric vehicle 12 may additionally operate in a hybrid electric vehicle (HEV) mode in which both the engine 14 and the motor 22 are used for vehicle propulsion. The HEV mode is an example of a charge-maintaining operating mode of the electric vehicle 12. During the HEV mode, the electric vehicle 12 may reduce the use of the motor 22 propulsion force in order to maintain the state of charge of the battery pack 24 at a constant or approximately constant level by increasing the engine 14 propulsion force. It is within the scope of the present invention that the electric vehicle 12 may operate in other operating modes in addition to the EV and HEV modes.

[0049] Figure 2 , 3 4 and 5 show a battery assembly 25 that can be used in an electric vehicle. For example, the battery assembly 25 can be Figure 1 Components of the battery pack 24 of the electric vehicle 12 are shown in FIG. The battery assembly 25 includes a plurality of battery cells 56 that store energy for supplying power to various electrical loads of the electric vehicle 12. Although Figure 2-4 A specific number of battery cells is described in the drawings, but a greater or lesser number of cells may be used in the battery assembly 25 within the scope of the present invention. In other words, the present invention is not limited to Figure 2-4 The specific configuration shown in .

[0050] The battery cells 56 may be stacked side by side along a longitudinal axis A to construct a battery cell group 56, sometimes referred to as a "battery stack". In one embodiment, the battery cells 56 are lithium-ion pouch cells. However, battery cells having other geometries (cylindrical, prismatic, etc.), other chemistries (nickel metal hydride, lead acid, etc.), or both may alternatively be used within the scope of the present invention.

[0051] The battery cells 56 may be housed within the array frames 57. For example, each array frame 57 may house one or more battery cells 56. In one embodiment, the array frames 57 also house heat sinks 59 (see Figure 4 ). Heat sinks 59 may be disposed between adjacent battery cells 56 of the battery stack to thermally manage any heat generated by the battery cells 56 .

[0052] The battery cells 56 of the battery assembly 25 can be supported by a support structure 58 disposed around the outer periphery of the battery stack. In one embodiment, the support structure 58 includes one or more array plate assemblies 60 and a plurality of support plates 61. At the same time, the array plate assemblies 60 and the support plates 61 can be interconnected to axially constrain the battery cells 56 in the stacked configuration.

[0053] The support structure 58 may optionally include one or more bindings 63 and one or more rods 65. The rods 65 may extend through the array plate assembly 60 and the array frame 57 to help constrain the battery cells 56 axially.

[0054] Each array plate assembly 60 may include an outer plate 84, an inner plate 86, and a spring plate 88 disposed between the outer plate 84 and the inner plate 86. The inner plate 86 abuts at least one of the battery cells 56, and the outer plate 84 is spaced apart from and therefore not abuts the battery cell 56. As discussed in more detail below, the spring plate 88 is configured to apply a compressive spring force to a battery stack of the battery assembly 25.

[0055] In one embodiment, the battery assembly 25 includes a single array plate assembly 60 disposed at a longitudinal extent 62 of the battery assembly 25. In this embodiment, the array plate assembly 60 serves as an end plate for the support structure 58 and extends parallel to the longitudinal axis A2 of the battery cells 56.

[0056] In another embodiment, the battery assembly 25 may include two array plate assemblies 60. In this embodiment, one array plate assembly 60 is disposed at each longitudinal extent 62 of the battery assembly 25 (see, for example, Figure 6 ).

[0057] In another embodiment, the array plate assembly 60 is disposed along a side 64 of the battery assembly 25 (see, for example, Figure 7 ). In this embodiment, the array plate assembly 60 serves as a side plate of the support structure 58 and extends perpendicular to the longitudinal axis A2 of the battery cell 56.

[0058] In yet another embodiment, the battery assembly 25 includes two array plate assemblies 60. In this embodiment, one array plate assembly 60 is disposed on each side 64 of the battery assembly 25 (see, for example, FIG. Figure 8 ).

[0059] In yet another embodiment, the support structure 58 includes an array plate assembly 60 disposed along both the longitudinal extent 62 and the sides 64 of the battery assembly 25 (see, for example, Fig. 9 ). In this embodiment, the battery assembly 25 includes four total array plate assemblies 60. The total number of array plate assemblies 60 and support plates 61 used within the battery assembly 25 is design specific and may depend on the amount of compressive force required to maintain a consistent battery stack size.

[0060] Reference now Figure 2-5, one or more battery cells 56 of the battery assembly 25 may bulge, swell, or otherwise expand during certain conditions, such as charging and discharging conditions. For example, one or more battery cells 56 of the battery assembly 25 may bulge, swell, or otherwise expand between a first position X (shown in dashed lines) and a second position X' (shown in solid lines). The battery cell 56 may bulge to any position between the first position X and the second position X'. The battery cell 56 may bulge in response to heat generation or a chemical reaction occurring within the battery cell 56.

[0061] In one embodiment, the first position X of the battery cell 56 generally refers to the uncharged profile of the battery cell 56, and the second position X' generally refers to the charged profile. The outer housing 66 of the battery cell 56 may include a first profile C1 that is generally flat (or less convex) at the first position X, and a second profile C2 that is generally non-flat (or more convex) at the second position X'. The varying profiles of the battery cells 56 of the battery assembly 25 may result in inconsistent battery stack sizes. For example, when one or more battery cells 56 convex toward the second position X', the total length of the battery assembly 25 may become larger. To address this issue, one or more array plate assemblies 60 of the support structure 58 may include a spring component that applies a compressive spring force to the battery stack so as to maintain a more consistent battery stack size despite the varying profiles of the battery cells 56. An exemplary spring plate equipped with such a spring component is discussed in more detail below.

[0062] Continue to refer to Figure 2-5 , Fig.10 , 11 12 shows an exemplary spring plate 88 for the array plate assembly 60 of the battery assembly 25. The spring plate 88 includes a plate body 68 and a spring member 70 protruding from the plate body 68. When the array plate assembly 60 is mounted to the battery assembly 25, the plate body 68 of the spring plate 88 can contact the outer plate 84 of the array plate assembly 60, and the spring member 70 can contact the inner plate 86 of the array plate assembly 60 (see, for example, Figure 4 ).

[0063] In one embodiment, the plate body 68 and the spring member 70 are integrally formed with one another to provide the spring plate 88. The spring plate 88 is therefore considered to be a unitary component excluding any mechanical attachments.

[0064] In the illustrated embodiment, the spring plate 88 includes a single spring member 70. However, it should be understood that the spring plate 88 may be designed to include any number of spring members 70 within the scope of the present invention. The total number of spring members 70 designed into the spring plate 88 may depend on the amount of compressive force required to maintain the compressed battery assembly 25.

[0065] The plate body 68 of the spring plate 88 includes an outer perimeter 72 formed by a plurality of beams 74. In one embodiment, the outer perimeter 72 is a rectangular perimeter. In another embodiment, the outer perimeter 72 is a square perimeter. However, other shapes are also contemplated within the scope of the present invention.

[0066] The spring member 70 of the spring plate 88 may include a contact surface 78 and a plurality of connecting plates 80 connected between the contact surface 78 and the beams 74 of the plate body 68. The contact surface 78 is generally flat and contacts the inner plate 86 or at least one battery cell 56 when the array plate assembly 60 is installed in the battery assembly 25 (see, for example, Figure 2-4 ). The opening 82 may extend between adjacent connecting plates 80 of the spring member 70 .

[0067] The configuration of the connecting plate 80 and the opening 82 imparts a "spring-like" characteristic to the spring member 70. For example, when one or more battery cells 56 of the battery assembly 26 are raised toward their second position X' (see Figure 5 ), the connecting plate 80, the contact surface 78, or both may bend (eg, exhibit elastic deformation) toward the retracted position RP (see Fig.10 ). In the retracted position RP, the spring member 70 has moved toward the plate body 68, and therefore has moved in a direction away from the battery stack (i.e., toward the outer plate 84). Moreover, when the battery cells 56 move back toward their first position X, the connecting plate 80, the contact surface 78, or both may bend back toward their deployed position EP, or back toward the battery stack (i.e., toward the inner plate 86). Thus, the spring member 70 is able to compensate for any dimensional changes in the battery stack.

[0068] Once the array plate assembly 60 has been mounted to the battery assembly 25, the spring member 70 protrudes from the plate body 68 in a direction toward the battery cells 56. In one embodiment, the spring member 70 selectively applies a compressive spring force to the inner plate 86 of the array plate assembly 60 to maintain a compressive force on the battery cells 56 passing through the battery assembly 25 (see Figure 2-4 ). The inner plate 86 of the array plate assembly 60 is designed to distribute the compression spring force more evenly to the battery stack.

[0069] The amount of compressive spring force applied by the spring member 70 can be adjusted to achieve any desired compressive force for any battery stack. In one embodiment, the compressive spring force applied by the spring member 70 can be changed by changing the thickness of the material of the connecting plate 80 and the contact surface 78, stacking one or more spring plates 88 together, etc.

[0070] Fig.13Another exemplary spring plate 188 is shown. The spring plate 188 includes a plate body 168 and a plurality of spring members 170 protruding from the plate body 168. In the illustrated embodiment, the spring plate 188 includes two spring members 170. However, it should be understood that the spring plate 188 may be designed to include any number of spring members 170 within the scope of the present invention. The spring plate 188 may be configured to apply a compressive spring force to more than one battery assembly of a battery pack, or to apply a compressive spring force to a battery stack including battery cells having a relatively large width.

[0071] In this embodiment, the body 168 of the spring plate 188 includes a central beam 176 extending between the spring members 170 of the spring plate 188. The central beam 176 provides structural support to the spring plate 188.

[0072] An exemplary battery assembly of the present invention includes an array plate assembly equipped with one or more integrated spring plates. The spring plate includes a spring-like component capable of maintaining the battery stack in a compressed state by applying a compressive spring force to the battery stack. The proposed design eliminates the need to provide a foam pad between the battery stack and the plate. The proposed design therefore utilizes fewer components and thus reduces cost and assembly time.

[0073] Although different non-limiting embodiments are shown as having specific components or steps, embodiments of the invention are not limited to those specific combinations. It is feasible to use some components or features from any non-limiting embodiment in combination with features or components from any other non-limiting embodiment.

[0074] It should be understood that like reference numerals identify corresponding or similar elements throughout the several drawings.It should be understood that although specific component arrangements are disclosed and shown in these exemplary embodiments, other arrangements may also benefit from the teachings of the present invention.

[0075] The foregoing description should be interpreted as illustrative rather than any limiting meaning. It will be appreciated by those skilled in the art that some modifications may fall within the scope of the present invention. For these reasons, the following claims should be studied to determine the true scope and content of the present invention.

Claims

1. A battery assembly comprising: a battery cell group; and An array plate assembly, the array plate assembly contacts at least one cell of the battery cell group, the array plate assembly includes a spring plate suitable for applying a compressive spring force to the at least one cell, wherein the spring plate includes a plate body having an outer periphery and one or more spring components, each of the spring components having a contact surface and a plurality of connecting plates connected to the contact surface and the outer periphery and openings arranged between adjacent connecting plates of the plurality of connecting plates. 2 . The battery assembly according to claim 1 , wherein the array plate assembly is disposed at a longitudinal extent of the battery cell group.

3. The battery assembly according to claim 1 or 2, wherein the array plate assembly is arranged along a side surface of the battery cell group.

4. The battery assembly of claim 1, wherein the spring member is movable between a deployed position and a retracted position when a profile of the at least one cell changes. 5 . The battery assembly of claim 4 , wherein the profile is changeable between a first profile and a second profile that is at least partially convex relative to the first profile. The battery assembly according to claim 1 , wherein the spring member protrudes from the plate body.

7. The battery assembly of claim 1, wherein the array plate assembly includes an outer plate and an inner plate, and the spring plate extends between the outer plate and the inner plate.

8. The battery assembly of claim 7, wherein the contact surface abuts the inner plate and the outer perimeter abuts the outer plate.

9. The battery assembly of claim 1, wherein the outer periphery is formed by a plurality of beams, each of the plurality of connecting plates being connected between the contact surface and the beam. 10 . The battery assembly of claim 1 , wherein at least one of the contact surface and the plurality of connection plates is flexible in response to a change in size of the battery cell group. 11 . The battery assembly of claim 1 , wherein the plurality of spring members include a first spring member and a second spring member adjacent to the first spring member.

12. The battery assembly of claim 11, comprising a center beam extending between the first spring member and the second spring member.

13. A method for a battery assembly, comprising: A compressive spring force is applied to a battery cell group of a battery assembly by means of an array plate assembly, wherein the array plate assembly includes a spring plate, and the spring plate is used to apply the compressive spring force based on the size profile of the battery cell group, wherein the spring plate includes a plate body having an outer periphery and one or more spring components, each of the spring components having a contact surface and a plurality of flexible connecting plates connected to the contact surface and the outer periphery, and openings arranged between adjacent flexible connecting plates of the plurality of flexible connecting plates.

14. The method of claim 13, wherein the spring member of the spring plate moves toward a retracted position in response to at least one cell in the battery cell group moving toward a more convex profile.

15. The method of claim 13, wherein the spring member of the spring plate moves toward a deployed position in response to at least one cell in the battery cell group moving toward a less convex profile.

16. The method of any one of claims 13-15, wherein the contact surface abuts at least one cell of the battery cell group or an inner plate of the array plate assembly.

17. The method of claim 16, wherein at least one of the contact surface and the plurality of flexible webs moves in response to the change in the dimensional profile so as to maintain the compressive spring force.

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