CN215008506U

CN215008506U - Battery module for battery pack

Info

Publication number: CN215008506U
Application number: CN202120545984.7U
Authority: CN
Inventors: V·埃斯瓦兰; K·特罗亚克; D·科瓦切尔文
Original assignee: Cummins Inc
Current assignee: Cummins Inc
Priority date: 2020-03-18
Filing date: 2021-03-16
Publication date: 2021-12-03
Anticipated expiration: 2031-03-16
Also published as: CN214706154U; GB2594916A; GB202003903D0

Abstract

The utility model discloses a battery module for group battery. The battery module (12) comprises a plurality of stackable battery cells (24, 24'). Each battery cell is one of two types, each type having a different configuration of electrical terminals. The battery cells (24, 24') are arranged such that they can only be stacked in one orientation. This may facilitate reconfiguration of the battery module to achieve different series and/or parallel configurations of the batteries.

Description

Battery module for battery pack

Technical Field

The present invention relates to a battery module for a battery pack, and in particular, to a battery module that can be constructed and easily maintained. The invention has particular, but not exclusive, application to battery packs for use in mobile applications such as electric or hybrid electric vehicles, construction equipment and the like.

Background

Electric and hybrid electric vehicles (e.g., cars, buses, vans, and trucks) typically use battery packs that are designed to have a high amp-hour capacity in order to provide electrical power for an extended period of time. Batteries typically include a large number of individual electrochemical cells connected in series and parallel to achieve the overall voltage and current requirements. To facilitate manufacturing, assembly, and maintenance, the cells in the battery pack may be grouped into modules. The module may include a support structure and a battery management unit to manage the charging and discharging of the battery.

To aid in packaging efficiency, some known battery modules use pouch cells (pouch cells). Pouch cells provide energy-intensive electrical storage in the form of a relatively thin and generally flat pouch. Typically, a plurality of pouch cells are stacked together inside a support structure to form a battery module. The cells in the module are connected in series and parallel to achieve the target voltage. This is typically accomplished by welding the terminal block to the battery terminals and connecting the bus bars to the terminal block to achieve the desired configuration.

In practice, it may be desirable to produce batteries that can be used in a variety of different applications. Accordingly, it may be desirable to produce battery modules that can be reconfigured to achieve different target voltages. However, existing battery modules are not easily reconfigured to achieve different output voltages.

During use of the battery pack, one of the cells may be damaged or otherwise damaged. In existing battery packs, this typically requires replacement of the entire module. However, this may be inefficient in terms of cost and material usage.

Batteries for electric vehicle applications tend to deteriorate during use and are typically designed for a lifetime of about ten years. When the battery packs no longer meet the electric vehicle performance standards, they may need to be replaced. However, the replacement battery pack may be reused in a second life (typically stationary) application. This can reduce the amount of waste and help reduce cost of ownership.

Battery packs may need to be refurbished before they are reused in a second life application, as different cells may degrade at different rates. However, existing battery packs are typically not constructed with consideration for the second use application. As a result, existing battery packs are not easily reconfigured or retrofitted for second-life applications.

It is therefore desirable to provide a battery module that can be easily configured to achieve different target voltages. It is also desirable to provide a battery module that is easy to service and that can be easily refurbished for a second life use.

SUMMERY OF THE UTILITY MODEL

According to an aspect of the present invention, there is provided a battery module for a battery pack, the battery module including a plurality of stackable battery cells, wherein:

each battery cell is one of two types, each type having a different configuration of electrical terminals; and is

The battery cells are arranged such that they can only be stacked in one orientation.

The present invention can provide an advantage in that, by arranging the battery cells into one of two types, each type having different configurations of electrical terminals, reconfiguration of the battery module can be facilitated. In particular, the battery module may be reconfigured to achieve different series and/or parallel configurations of the batteries. This may be accomplished, for example, by changing the order of the battery cells in the battery module and/or changing the bus bars used to connect the battery cells.

The battery cells are arranged such that they can only be stacked in one orientation. For example, each battery cell may include a locating feature, such as a protrusion on one side and a recess on the other side, where the protrusion on one side is arranged to engage with a corresponding recess in an adjacent battery cell. This may help ensure that the battery cells can only be stacked in the correct orientation, which helps ensure that only the correct electrical connections can be made.

The electrical terminals are preferably terminals for connecting the battery cell to other components such as a bus bar.

Preferably, the electrical terminals of one type of battery cell are in a different location on the battery cell than the electrical terminals of another type of battery cell. This may facilitate the reconfiguration of the battery module.

For example, each battery cell may include positive and negative terminals, and the positive and negative terminals of one type of battery cell may be on opposite sides of the battery cell from the positive and negative terminals of another type of battery cell. Thus, the positive terminal of one type of battery cell may be on the same side of the battery cell as the negative terminal of another type of battery cell, or vice versa.

Alternatively or additionally, the electrical terminals of one type of battery cell may be displaced from the edge of the battery cell by a different amount than the other type of electrical terminals. Thus, one type of terminal may be closer to the edge of the battery cell than another type of terminal. This may help ensure that when two battery cells of different types are stacked adjacent to each other, there is sufficient electrical isolation between the negative and positive terminals of the respective battery cells.

Preferably, each battery unit comprises a pouch battery and a battery tray. The use of pouch cells can help provide energy-intensive electrical storage.

Preferably, the battery tray comprises a battery frame surrounding the edges of the pouch battery. This can help support the pouch cell while minimizing weight. Furthermore, in the case of applying pressure to a pouch cell by compressing the foam, the use of a cell frame around the edge of the pouch cell can help ensure that pressure is applied evenly to all the pouch cells in the stack and can help prevent excessive compression of the foam. This in turn can help extend the life of the pouch cell.

Each battery cell may further comprise a battery cover arranged to clamp the pouch battery. Thus, the pouch battery can be clamped between the battery frame and the battery cover. This may facilitate assembly, and may also allow the battery cell to be easily disassembled. Preferably, the battery cover is disposed along one edge of the battery cell (e.g., the same edge as the electrical terminals), although other arrangements are possible.

The battery cells are preferably arranged such that they can be disassembled. For example, the battery unit may be disassembled by separating the battery frame from the battery cover. This may allow for easy replacement of components of the battery cell. For example, if a single pouch battery has failed, the pouch battery can be replaced without replacing the entire module.

The electrical terminals may include terminal blocks that may be used to connect the battery cells in a desired series and/or parallel configuration, for example, using bus bars. The terminal block is preferably attached to the electrical terminal of the pouch cell, for example by welding. In the case where the battery cell includes a battery cover, then the battery cover may be arranged to clamp the terminal block between the battery cover and the battery tray. This may facilitate assembly of two different types of battery cells.

The terminal blocks of one type of battery cell may be different from the terminal blocks of another type of battery cell. For example, the terminal blocks of one type of battery cell may have their electrical terminals at different locations on the battery cell than the electrical terminals of another type of terminal block. Thus, different types of battery cells may have their electrical terminals in different positions even when the pouch battery has its electrical terminals in the same position.

Preferably, the terminal block includes an aperture for removably connecting an electrical connector, such as a busbar. The bore may be threaded to receive a threaded pin. This may facilitate connection and/or reconfiguration of the battery module.

The battery module may further include a bus bar unit for electrically connecting the plurality of batteries. The bus bar unit may include a plurality of bus bars. The bus bar may be laminated between multiple insulating sheets, for example. This may facilitate connection of the battery modules in a desired series and/or parallel configuration. Furthermore, by changing the stacking order of the bus bar units and/or the battery cells, the reconfiguration of the battery module can be easily achieved.

Preferably, the bus bar unit is replaceable in order to reconfigure the battery module. Therefore, the battery module may be reconfigured by replacing the bus bar unit with a different bus bar unit having a differently configured bus bar in order to reconfigure the electrical connection of the battery cells.

Thus, it will be understood that a plurality of battery cells may be connected in series and/or parallel using bus bar units, and that the modules may be arranged such that the series and/or parallel connections may be changed by changing the stacking order of the battery cells and/or the bus bars. This may allow for easier reconfiguration of the battery module than previous arrangements, which typically involved disconnecting and reconnecting weld joints.

The battery module may include a stack of battery cells and at least one end plate. Preferably, two end plates are provided, one at each end of the stack of battery cells. The end plates may serve as structural supports to help maintain the size and shape of the battery module. In addition, the end plates may be used to apply pressure to the pouch cells in the battery cell.

The battery module may further include an expansion gasket between each of the battery cells. The expansion liner may be, for example, a layer of compressible foam. This may help ensure that the proper pressure is applied to the cells when the battery module is compressed. This may help to extend the life of the battery.

Preferably, the battery modules are held together by a module band. For example, where a battery module includes a stack of battery cells and two end plates, a module band may be passed around each end plate. This may help maintain the stack of battery cells and the end plates in a desired shape while minimizing the size and weight of the battery module.

The modular belt may be made of metal, such as steel, or of any other suitable material, such as a fibre or plastic based material. The module band may be provided as a strip that wraps around the module while the module is in a compressed state. The ends of the strip may then be secured together, for example by crimping or any other suitable fastening method. In one embodiment, three modular belts are used, although another number of modular belts, such as two, four, five, or any other number, may be used instead. Preferably, a gap is left between adjacent modular belts.

The advantage of using such a modular belt is that the modules can be easily assembled. For example, the modules may be assembled by stacking the cells together, adding end plates to the stack, compressing the stack, and then adding the module strips while the stack is in a compressed state. This may also provide the advantage that the module band may keep the stack of battery cells in compression, which may help ensure that the proper pressure is applied to the battery. Furthermore, the battery module can be easily reconfigured by removing the module tape. Once the modules are reconfigured, the modules may be compressed and new module bands added.

Drawings

Preferred features of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

fig. 1 shows a diagrammatic view of a battery pack;

FIG. 2 shows components of a battery module;

fig. 3 is an exploded view of a battery module;

FIG. 4 shows components of the battery cell in more detail;

fig. 5A and 5B show examples of battery cells having two different configurations;

FIG. 6 shows components of a battery module having a plurality of battery cells stacked together;

FIG. 7 illustrates how laminated bus bars may be used to connect battery modules;

FIG. 8 illustrates the basic principle of a modular clamping assembly;

FIG. 9 shows an example of a module clamping plate;

FIG. 10 is a cross-sectional view through a portion of the module clamping assembly;

FIG. 11 shows the components of the clamping assembly in more detail;

12A and 12B illustrate examples of cross members that may be used with a battery pack;

FIG. 13 shows the components of the battery pack with the module and module clamp in place;

fig. 14A and 14B show examples of positioning pins and supporting pins;

fig. 15 schematically illustrates the positions of the positioning pins and the support pins with respect to the battery module;

FIG. 16 schematically illustrates holes in the bottom of the module for receiving locating pins;

fig. 17 shows the bottom of the battery module; and

figure 18 schematically shows the components of the clamping device.

Detailed Description

Battery pack

Fig. 1 illustrates one type of battery pack with which embodiments of the present invention may be used. The battery pack of fig. 1 is designed for use with electric and hybrid vehicles, particularly in high horsepower applications such as buses, trucks, vans, construction equipment, and the like. However, the principles of the present invention may be applied to any type of battery pack used in any suitable application.

Referring to fig. 1, a battery pack 10 includes a plurality of battery modules 12, a plurality of cooling plates 14, a cross member 15, a battery management system 16, a module holder 18, a surrounding frame 20, a top panel 21, and a bottom panel 22. In this example, fifteen battery modules 12 are arranged in five rows of three modules each. Three battery modules 12 of each row are located on a corresponding cooling plate 14. The cooling plate 14 is hollow to allow coolant flow. The cross members 15 are disposed between the rows of the battery modules. The battery management system 16 is located at one end of the battery pack. In the assembled state, the cross member 15 is attached to the surrounding frame 20 and spans the frame from side to side. Top and

bottom panels

21 and 22 are attached to the top and bottom of the frame 20 and cross member 15, respectively. The battery module 12, the cooling plate 14, the battery management system 16 and the holder 18 are housed inside the frame 20 and the

panels

21, 22. The module retainer 18 serves to hold the battery module 12 and other components in place.

As will be discussed below, embodiments of the present invention relate to a battery module assembly that is configurable, easily serviceable, and which helps ensure structural rigidity and module restraint.

Battery module

Fig. 2 shows components of a battery module in an embodiment of the present invention. Referring to fig. 2, in this example, battery module 12 includes twenty-four battery cells 24 stacked together side-by-side. The battery cells 24 are electrically connected in series and/or parallel to achieve a battery pack target voltage. End plates 26 are provided on each side of the module. The battery cells 24 and end plates 26 are held together by steel straps 28. A removable cover 30 is provided at one end of the module. A battery management unit is integrated with the module 12 to monitor and manage battery charging and other aspects of battery operation.

Fig. 3 is an exploded view of the battery module. Referring to fig. 3, the battery module 12 is formed by stacking a plurality of battery cells 24 together. A compressed foam expansion gasket 36 is disposed between adjacent battery cells. Each battery cell 24 is in the form of a pouch battery 32 held within a battery tray 34. In this example, the battery tray 34 is made of a plastic polymer material, such as a thermoplastic. Each battery cell 24 includes an electrical terminal block 38 for making electrical connections with the pouch cell 32. Each battery cell 24 also has a cooling fin 40 for conducting heat away from the pouch cell 32. In fig. 3, the cooling fin 40 is provided on the rear side of the battery. Each cooling fin includes a tab 41 that extends around the bottom of the cell. The tabs 41 are designed to contact the cooling plate in order to conduct heat away from the battery. The cooling fins 40 are made of a thermally conductive material, such as aluminum or graphite. A thermally conductive, electrically insulating film is disposed over the cooling fins.

In the arrangement of fig. 3, laminated bus bars 42 are used to electrically connect the individual battery cells 24. The laminated bus bar 42 is connected to the battery cell 24 by means of a conductive pin 44. Pins 44 pass through holes in the bus bar 42 and into corresponding holes in the terminal block 38 of the battery cell to provide electrical and mechanical connection between the two. The laminated bus bar 42 includes electrical conductors that connect the battery cells 24 in the desired series and/or parallel connections to achieve the target voltage. The laminate bus bar 42 is also connected to positive and negative terminals 45 that provide electrical connections to and from the battery modules.

Also shown in fig. 3 is a unified battery management unit 46. The battery management unit 46 is used to monitor and manage battery charging and other aspects of battery operation. The battery management unit 46 is disposed on a circuit board that is mounted on the laminated bus bar 42 via an electrical insulation barrier plate 48. A plurality of temperature and voltage sensors are disposed on the laminate bus bar 42 and are used by the battery management unit 46 to monitor battery temperature and voltage. The battery management unit 46 is protected by a removable cover 30. The removable cover 30 is made of a plastic polymer material, such as a thermoplastic.

To assemble the battery module, individual battery cells 24 (including pouch cells 32, battery tray 34, terminal block 38, cooling plate 40, and battery cover 50) are stacked together with thermally conductive foam expansion gaskets 36 between each adjacent battery cell. The battery tray includes a positioning feature such that the battery cells can only be stacked in one orientation. An end plate 26 is then added to each side of the stack of battery cells. The stack of cells is then compressed to the desired pressure. This ensures that the foam expansion gasket 36 provides the required pressure to each pouch cell 32. A steel band 28 is placed around the stack of cells while the stack is held under pressure. The end plate includes a recess for positioning the steel strip. The ends of the steel strip are then crimped together. Thus, the steel belts ensure that the required pressure is maintained against the cells in the module, and the size and shape of the battery module is maintained.

Constructability

The target voltage of the battery module and/or the battery pack may vary depending on the application. However, existing battery modules are often produced at a single target voltage. Typically, battery modules have bus bars that are welded to the cells in the module. It has been found that such battery modules may be difficult to reconfigure to achieve different output voltages.

In an embodiment of the invention, the battery modules are designed to allow for changing the series/parallel connection of the modules. This may allow the target output voltage of the module to be changed to achieve the target battery pack voltage.

Fig. 4 shows the components of the battery cell in more detail. Referring to fig. 4, the battery unit 24 includes a pouch battery 32, a battery tray 34, a terminal block 38, a cooling sheet 40, and a battery cover 50. The pouch cell 32 is an electrochemical cell (typically a lithium ion cell) disposed in a pouch. Such pouch cells are commercially available and will not be described further. The terminal block 38 is made of a conductive material, such as copper, and is used to make electrical connections with the pouch cell 32. The terminal block 38 is welded to the battery terminal 37 using, for example, ultrasonic welding. The battery tray 34 frames the pouch cells 32 and serves to hold the pouch cells in place. The battery tray 34 is made of a plastic polymer material, such as a thermoplastic. A cooling fin 40 is attached to the battery tray 34 to contact the pouch battery 32. The cooling fins 40 are made of a thermally conductive material such as aluminum or graphite. In the case where the cooling fin is made of a metal material, it may be coated with a high-voltage insulating film. The cooling fins 40 include tabs 41 that extend around the bottom of the battery tray 34. The tabs 41 are designed to contact the cooling plate in order to conduct heat away from the battery. The battery cover 50 is attached to the battery tray 34 such that the terminal block 38 and the top of the pouch battery 32 are clamped between the battery cover and the battery tray. The battery cover may be attached to the battery tray 34 using heat staking, but other techniques such as plastic rivets may alternatively be used.

In an embodiment of the present invention, two different types of battery cells 24 are provided. In the first type, the positive and negative terminals of the battery cells are arranged in a first configuration, and in the second type, the positive and negative terminals of the battery cells are arranged in a second configuration.

Fig. 5A and 5B show examples of battery cells 24 having two different configurations. In each case, a terminal block 38 is disposed on top of the pouch cell 32, sandwiched between the battery tray 34 and the battery cover 50, and attached to the terminals of the pouch cell 32. However, the battery cells of fig. 5A and 5B differ in that the positive and negative terminals are on opposite sides of the battery. Thus, in the arrangement of fig. 5A, the positive terminal of the battery cell 24 is on the left hand side of the battery, while its negative terminal is on the right hand side of the battery. On the other hand, in the arrangement of fig. 5B, the negative terminal of the battery cell 24' is on the left-hand side, while the positive terminal thereof is on the right-hand side.

In addition, in the arrangement of fig. 5A and 5B, the two battery cells have different types of terminal blocks. The two types differ in the location of the electrical contacts for connection to the laminated bus bar. In the first type of battery cell shown in fig. 5A, the terminal block 38 has electrical terminals 39 towards the outer edge of the battery cell. On the other hand, in the second type of battery cell as shown in fig. 5B, the terminal block 38 'has the electric terminals 39' closer to the center of the battery cell than in the case of the first type. If desired, the battery trays 34 may have different colors or be otherwise marked to indicate which configuration of electrical terminals they have.

Fig. 6 shows components of a battery module in which a plurality of battery cells of each of two configurations are stacked together. Referring to fig. 6, it can be seen that the electrical terminals of the cells are arranged in a total of four rows. In fig. 6, from top to bottom: the first row includes the positive terminals of the first type of battery cells 24; the second row includes the negative terminal of the second type of battery cell 24'; the third row includes the negative terminal of the second type of battery cell 24'; the fourth row includes the negative terminals of the first type of battery cells 24. By placing the electrical terminals of the second type of cell more centrally than the electrical terminals of the first type of cell, sufficient electrical isolation is maintained between the respective positive and negative terminals.

The battery cells also include locating features 51 that ensure that they can only be stacked in one orientation. In particular, each battery cell comprises a protrusion on one side and a recess on the other side, wherein the protrusion on one side is arranged to engage with a corresponding recess in an adjacent battery cell. This ensures that the cells are not misconnected.

The advantage of the above arrangement is that it is easy to connect the various batteries in the required series and parallel configurations. For example, two adjacent battery cells of the same type can be easily connected in parallel because their positive and negative terminals are both adjacent to each other. Furthermore, two (or more) adjacent battery cells of opposite type can easily be connected in series, since the positive terminal of the first type is adjacent to the negative terminal of the second type, and vice versa.

Fig. 7 shows in more detail how the laminated bus bars are used to connect the cells in the battery module. Referring to fig. 7, the laminated bus bar 42 is connected to the battery cell 24 by means of a conductive pin 44. The pins pass through holes in the bus bar 42 and into corresponding holes in the terminal block of the battery cell. The end of the pin is threaded and engages threads in a hole in the terminal block.

The laminated bus bar of fig. 7 includes a plurality of bus bars held between plastic sheets. In the example of fig. 7, the bus bar is arranged to connect two adjacent battery cells of the same type in parallel. The bus bars are also arranged to connect each (parallel-connected) pair of battery cells in series by connecting the positive terminal of one pair to the negative terminal of an adjacent pair, connecting the negative terminal of that pair to the positive terminal of the next pair, and so on throughout the module. Therefore, in practice, the paired battery cells are connected in a zigzag manner in the entire module. A module terminal is located at each end of the bus bar.

The described arrangement allows for easy reconfiguration of the module to achieve different voltage and/or capacity requirements. For example, if it is desired to connect all batteries in series to increase the module voltage, this may be accomplished by alternating the individual battery cells of each type of battery cell. On the other hand, if it is desired to reduce the voltage (and increase the capacity), three or more battery cells of the same type may be provided that are adjacent to each other and connected in parallel. Thus, for example, the modules may be connected: twenty-four batteries are connected in series; the cells in one pair are connected in parallel, and twelve pairs of cells are connected in series; the three batteries are connected in parallel to form a group, and the eight groups of batteries are connected in series; and so on. In each case, the laminated bus bars were modified to achieve the appropriate connections between the cells.

Thus, it will be appreciated that the module can be easily reconfigured by changing the stacking order of the cells and the laminate bus bar design.

Maintainability

During use of the battery pack, one of the cells may be damaged or otherwise damaged. Furthermore, battery packs for electric vehicle applications tend to deteriorate during use and are typically designed for a lifetime of about ten years. When the battery packs no longer meet the electric vehicle performance standards, which typically include maintaining 80% of the total available capacity, they may need to be replaced. However, the battery pack may still be used in secondary life applications, where the battery pack is typically held stationary.

With the modular design described above, the module can be serviced to battery level. Thus, for example, individual batteries that have become damaged can be replaced without the need to replace the entire module.

Furthermore, the modular design described above may make it easier to reuse the module for a second life use. Thus, once the module no longer meets the electric vehicle performance standards, it can be easily disassembled to battery level. This can be achieved simply by removing the metal strip. The battery can then be reassembled for other (typically stationary) electrical storage applications. This can reduce the amount of waste material and help reduce cost of ownership.

Module belt

The above-described module design uses module straps and end plates to meet structural rigidity requirements and provide the required compression for the cells, while helping to minimize the size and weight of the module.

The primary function of the modular belt is to maintain the shape and size of the modules and compress the foam expansion pads to the desired pressure. Applying external pressure to the cell in this manner can have significant benefits to the operation of the cell. In particular, the application of pressure may increase the battery capacity and decrease the discharge ohmic resistance.

The modular belt also allows the module to be easily disassembled for servicing or reusing the battery. The disassembled modules can be easily reassembled by applying new metal strips.

In a preferred embodiment, the modular belt is made of metal, such as steel. However, other materials, such as plastics or fibre-based materials, may also be used.

Module clamping

When the battery modules are assembled in a battery pack, it must be ensured that they are properly held and maintain optimal contact with the cooling plate.

In an embodiment of the present invention, the module clamping plate is used to fix the battery module in the battery pack. The module clamping plates are attached to a battery pack cross member that spans the width of the surrounding frame 20 shown in fig. 1. The module clamping plates also connect adjacent cross members to increase the rigidity of the structure. The module clamping plate utilizes a designed gap between the cross member and the module clamp to apply the required compressive force through the supporting foam to optimize thermal contact of the module cooling fins with the cooling plate. An epoxy coating may be used to electrically isolate the module clamping plate from the module.

Fig. 8 shows the basic principle of the module clamping assembly. Referring to fig. 8, the clamping assembly includes a module clamping plate 52, a battery pack cross member 15, a gap spacer 54, a locating pin 56, a cooling plate 14, a cooling plate support foam 58, and a battery pack bottom panel 22. Also shown in fig. 8 are the battery module 12 and the battery pack top panel 21.

In the arrangement of fig. 8, a module clamping plate 52 is connected to the battery cross member 15 on each side. This applies downward pressure to the battery module 12. Some of this downward pressure is applied from the battery modules 12 to the top of the cooling plate 14 through the gap spacers 54. The counter pressure is applied from the bottom panel 22 through the support foam 58 to the bottom on the cold plate. The battery module 12 is located on the locating pins 56. The locating pins 56 are connected to the bottom panel 22 and pass through holes in the cooling plate 14. The tops of the locating pins 56 engage holes in the bottom of the battery module 12. The locating pin includes a shoulder that acts as a compression stop. This limits the load applied to the cooling plate. The remaining load is applied to the bottom panel 22 by the dowel pins 58.

Fig. 9 shows an example of a module clamping plate in an embodiment of the invention. Referring to fig. 9, the clamping plate 52 is substantially flat and has a dimension slightly larger than the dimension of the top of the battery module 12. Slots 60 are provided in the clamping plate to allow air flow and reduce weight. The clamping plates include

holes

62, 63 that allow the clamping plates to be attached to the battery pack cross member. In this example, the clamping plate 52 is made of a metal having a high strength to weight ratio, such as an aluminum alloy. An epoxy coating is applied for electrical insulation.

Fig. 10 is a cross-section through a portion of the module clamping assembly showing how the module clamping plates are attached to the cross member. Referring to fig. 10, the module clamping plate 52 is attached to the cross member 15 via a module clamping bushing 64. The module clamping plate 52 is attached to the module clamping bushing 64 using bolts 65. The module clamping bushing 64 is attached to the cross member 15 using a bolt 66, the bolt 66 passing through a hole in the bushing 64 and into a threaded hole in the top of the cross member 15. Figure 11 shows in more detail the portion of the clamping assembly surrounding the clamping bush.

In the arrangement of fig. 10 and 11, the modules and module clamp assemblies are dimensioned so that a small gap 68 remains between the bushing 64 and the cross member 15. This small gap ensures that the clamping plate 52 can apply downward pressure to the module 12. The amount of downward pressure can be reconfigured by adjusting the machining height of the cross member 15. During assembly, the required pressure may be achieved by tightening the bolts to the required torque.

Fig. 12A and 12B show in more detail two types of cross members that may be used in a battery pack as shown in fig. 1. Referring to fig. 12A and 12B, the cross members 15, 15' have a generally open structure and are designed to provide rigidity to the surrounding frame 20 while minimizing weight. The cross member includes bolt holes for connecting the cross member to the surrounding frame and bolt holes for connecting the cell panel to the cross member. The cross member also includes mounting points for bushings 64 shown in fig. 10 and 11.

Fig. 13 shows the components of the battery pack with the module and module clamp in place. Referring to fig. 13, a module clamping plate 52 is placed over each battery module 12 and attached to the cross member 15 in the manner described above.

The clamping arrangement described above may allow uniform pressure to be applied to the cooling plate 14 by the battery modules 12. This may help ensure uniform cooling of the batteries within the module, which may help extend the life of the module. Further, it has been found that the structural rigidity of the battery pack can be improved by connecting the battery pack cross member 15 using the module clamping plate 52. In particular, connecting the cross members may improve the torsional stiffness of the battery pack, which may help prevent the battery pack from twisting during use.

A gap is designed in the clamping arrangement between the module clamping plate and the cross member in order to apply a compressive force ensuring a thermal contact pressure between the module and the cooling plate.

Module constraints

When the battery modules are assembled in a battery pack, it must be ensured that they are properly positioned, constrained and maintain optimal contact with the cooling plates. However, swelling and tolerance build-up of the battery during use can make this difficult to achieve.

Referring back to fig. 8, the clamping assembly includes locating pins 56 for locating the battery module in the battery pack. Dowel pins 56 are attached to the bottom panel 22 and pass through holes in the cooling plate 14. The tops of the locating pins 56 engage holes in the bottom of the battery module 14.

In one embodiment, three locating pins and one support pin are used to locate and support each module. Fig. 14A and 14B show examples of a positioning pin and a supporting pin, respectively.

Referring to fig. 14A, locating pin 56 includes a base portion 70, a pin portion 72, and a shoulder 74. The bottom of the base portion 70 is designed to fit into a shallow hole in the battery bottom panel 22. The top of the base portion 70 is designed to pass through a hole in the battery pack cooling plate 14. The pin portion 72 is designed to fit into a hole or slot in the battery module 12. The holes or slots in the battery modules are sized so that the battery modules are located on the shoulders 74 of the locating pins.

Referring to fig. 14B, the support pin 76 includes a base portion 78 and a pin portion 80. The bottom of the base portion 78 is designed to fit into a shallow hole in the battery bottom panel 22. The top of the pin portion 80 is at approximately the same height (relative to the bottom panel 22) as the shoulder 74 of the locating pin 56.

Fig. 15 schematically shows the positions of the positioning pins and the support pins with respect to the battery module. Referring to fig. 15, each of the positioning pins 56 is located at one of three corners of the battery module. The support pin 76 is located at a fourth corner of the battery module. The position of the battery module relative to the pins is shown by the dashed lines.

Fig. 16 schematically shows holes provided in the bottom of the module to receive the locating pins. In fig. 16, the x-direction is along the longitudinal direction of the battery pack, the y-direction is across the lateral direction of the battery pack, and the z-direction is the vertical direction within the battery pack. Referring to fig. 16, the module includes a circular hole 80 and two oblong holes or slotted

holes

82, 83. The circular holes 80 serve as position restricting means to restrict the movement of the battery module in the x and y directions. The slotted holes 82 serve to constrain movement of the battery module in the y-direction, but allow some movement in the x-direction. This allows for some end-to-end tolerances in the battery modules. The slotted holes 83 serve to constrain movement of the battery module in the x-direction, but allow some movement in the y-direction. This allows for some side-to-side tolerance in the battery module. Fig. 16 also shows a gasket 84 disposed on the bottom of the battery module 12. The pad 84 is designed to rest on the support pin 76. This helps to ensure uniform compression of the battery module on the cooling system.

Fig. 17 illustrates a bottom of a battery module in one embodiment. Referring to fig. 17, battery module 12 includes a stack of battery cells 24 held together by steel straps 28 and two end plates 26. A circular hole 80 and an elongated slot hole 82 are provided in one of the end plates 26. The slotted hole 83 and the gasket 84 are provided on the other end plate 26.

The above arrangement helps to improve the thermal conductivity between the module and the cooling system and also allows for expansion and tolerance build-up of the battery.

FIG. 18 is a schematic view of the components of the clamping device showing how dynamic loads are applied by the locating pins. Referring to fig. 18, the alignment pins 56 (and support pins 76) are attached to the battery pack bottom panel 22. The face sheet 22 is composed primarily of carbon fiber face sheets. The battery module 12 is located on the locating pins 56 and the support pins 76 that pass through holes in the cooling system. The module 12 is pushed down by the module clamping plate. The module is stopped on the positioning pins 56 and the support pins 76 by the force F of the jig. Below the module, from top to bottom, there are thermal conductive pads (gap pads) 54, cooling plates 14, and support foam 58. The support foam 58 is attached to the bottom panel 22. The supporting foam distributes the load from the cooling plate 14 to the bottom panel so as not to damage the cooling plate. The cooling foam also provides thermal insulation between the cooling plate and the bottom panel.

In the above arrangement, the amount of load applied to the cooling plate by the battery module may be adjusted based on the selection of the thickness of the cooling foam and the properties of the foam, such as the foam material and its compression curve. Thus, the pressure applied to the cooling plate is the pressure required to compress the foam (and gap spacer) sufficiently for the battery module 12 to rest on the shoulders of the positioning pins 56 and the support pins 76. The pressure is chosen to be large enough to ensure good thermal contact between the module and the cooling plate, but small enough to avoid deforming the cooling plate. Any additional force is transmitted through the locating pins and support pins rather than through the cooling plate. Thus, if a dynamic load is generated by an impact or other movement of the battery pack, the dynamic load will be transferred through the pins rather than the cooling system.

An advantage of the above arrangement is that the cooling plate can be made lighter and thinner than would otherwise be the case, since it does not absorb dynamic loads. Furthermore, deformations of the cooling plate, which might otherwise occur due to dynamic loads, can be avoided. Furthermore, a single cooling plate may be used for a row of battery modules, rather than providing a separate cooling plate for each module. This may result in a further reduction of the weight of the cooling system and/or an improvement of the coolant flow, resulting in an improvement of the cooling efficiency.

In this embodiment, the bottom panel 22 serves as a counter clamping component for the replaceable battery module. The battery modules are seated on the pins and the spacers, which results in uniform pressure distribution between the battery module cooling fins and the cooling plate interface. Accurate module positioning helps to keep the cooling plates at the same level, helping to avoid pressure drops in the cooling system. Furthermore, the above arrangement helps to achieve better flexibility in battery placement in the vehicle with respect to other groups in the system.

Claims

1. A battery module for a battery pack, the battery module comprising a plurality of battery cells that are stackable, characterized in that:

2. The battery module of claim 1, wherein the electrical terminals of one type of cell are in a different location on a cell than the electrical terminals of another type of cell.

3. The battery module for a battery pack of claim 1 or 2, wherein each battery cell comprises a positive terminal and a negative terminal, wherein the positive terminal and the negative terminal of one type of battery cell are on opposite sides of a battery cell from the positive terminal and the negative terminal of another type of battery cell.

4. The battery module for a battery pack of claim 1 or 2, wherein the electrical terminals of one type of battery cell are displaced from the edges of the battery cell by a different amount than the electrical terminals of another type.

5. The battery module for a battery pack according to claim 1 or 2, wherein each battery cell comprises a pouch battery and a battery tray.

6. The battery module for a battery pack of claim 5, wherein the battery tray comprises a cell frame surrounding the edges of the pouch cells.

7. The battery module for a battery pack of claim 6, wherein each battery cell further comprises a cell cover arranged to clamp the pouch cell.

8. The battery module for a battery pack according to claim 7, wherein the battery cell is detachable by separating the battery frame from the battery cover.

9. The battery module for a battery pack according to claim 1 or 2, wherein the electric terminals comprise terminal blocks.

10. The battery module of claim 9, wherein the terminal block includes holes for removably connecting electrical connectors.

11. The battery module for a battery pack according to claim 1 or 2, further comprising a bus bar unit for electrically connecting the plurality of battery cells, the bus bar unit including a plurality of bus bars.

12. The battery module for a battery pack of claim 11, wherein the bus bar unit comprises a plurality of bus bars laminated between sheets of electrically insulating material.

13. The battery module for a battery pack of claim 11, wherein the bus bar unit is replaceable to reconfigure the battery module.

14. The battery module for a battery pack according to claim 1 or 2, wherein the plurality of battery cells are connected in series and/or in parallel using a bus bar unit, and the battery module is arranged so that the series and/or parallel connection can be changed by changing a stacking order of the battery cells and/or the bus bars.

15. The battery module for a battery pack of claim 1 or 2, wherein the battery module comprises a stack of battery cells terminating in at least one end plate.

16. The battery module for a battery pack according to claim 1 or 2, further comprising an expansion gasket between the respective battery cells.

17. The battery module for a battery pack according to claim 1 or 2, wherein the battery module is held together by a module band.