Method for manufacturing battery stacks

Abstract

Method for producing battery stacks (10), wherein battery cells (12) having a, at least substantially, cuboid basic shape, according to which they have a thickness direction and two surface faces oriented perpendicular to the thickness direction, wherein the dimensions of the battery cells (12) in the thickness direction are significantly smaller than in the directions parallel to the surface faces, are arranged in a stack in which adjacent battery cells (12) are oriented with their surface faces towards each other, wherein, prior to arranging the battery cells (12) into the battery stack (10), a change in the respective relative orientation of the battery cells (12) to their respective transport direction (T) is carried out such that, after this change in their respective orientation, the battery cells (12) are transported with their thickness direction parallel to their respective transport direction (T), wherein the change in the respective orientation of the battery cells (12) relative to their respective transport direction (T) takes place while maintaining a continuous transport movement, wherein, to enable the change in their respective orientation relative to their respective transport direction (T), the battery cells (12) are lifted from a conveyor device (16) with which the battery cells (12) are transported by means of a manipulator device (18) before the change in their respective orientation relative to their respective transport direction (T) and, after the change in their respective orientation relative to their respective transport direction (T), are placed on the conveyor device (16) or on another conveyor device (20), characterized in that the battery cells (12) are rotated about a vertical axis relative to their respective transport direction (T) during the change of their respective relative orientation to their transport direction (T), wherein the gripping devices (24) each engage the battery cells (12) by means of an adhesive gripper.

Description

[0001] The invention relates to a method for manufacturing battery stacks.

[0002] In modern battery systems, such as those used in electric vehicles, battery cells are regularly grouped into battery stacks. These battery stacks are then placed in housings and / or secured using mechanical means, such as frames and / or other enclosing or clamping elements. This transforms the battery stacks into manageable units.

[0003] Arranging the battery cells into a battery stack is a critical step in the production of such battery systems. This is because a large number of battery cells must be handled to produce a single battery stack. Consequently, the challenge in feeding the battery cells to the production area where they are arranged into a stack is to feed in a large number of cells quickly, so that the production speed of the battery stacks is not slowed down by the time required for cell feeding.

[0004] The arrangement of the battery cells into the stacks is typically carried out in such a way that the battery cells are conveyed into a work area used for the production of the stack with an orientation that corresponds to their orientation in the stack.

[0005] Depending on the processes preceding the arrangement of the battery cells into stacks, the battery cells may initially be transported in an orientation unsuitable for stacking. Therefore, it is necessary to first orient the battery cells relative to their transport direction into a suitable orientation for arranging them into the stack.

[0006] According to the state of the art, clocked systems are used for this purpose, in which, for example, battery cells are gripped with grippers and placed on a conveyor belt in an orientation suitable for arranging the battery cells into a stack, which then conveys the battery cells, which are then oriented appropriately to the direction of transport, into the working area in which the arrangement of the battery cells into the stack takes place.

[0007] In such timed processes, the conveyed cells inevitably come to a standstill and must then be accelerated again. The resulting movement patterns require high accelerations of the moving elements involved and are inherently prone to malfunctions, as the rapid movements of the manipulation devices used naturally compromise positioning accuracy.

[0008] US Patents 5,988,354 A, 2019 / 0241,371 A1, and 10,894,673 B2 disclose methods for transporting objects, in which the objects are transferred from one transport device to another. However, these methods are only suitable for transferring objects transported flat into another flat transport operation.

[0009] DE 10 2013 205 574 B4 discloses a method for assembling battery pack components in which cells are moved from an orientation in a horizontal plane to an orientation in a vertical plane. The cells are pivoted about a horizontal axis in this process.

[0010] The invention is therefore based on the objective of enabling a reliable and rapid supply of battery cells in an orientation of the battery cells relative to their transport direction that is suitable for the production of the stacks during the manufacture of battery cell stacks.

[0011] The problem is solved by a method having the features of claim 1. The features of the dependent claims relate to advantageous embodiments.

[0012] The process for manufacturing battery stacks involves arranging battery cells into a stack. These battery cells have a cuboid shape, at least in essence. Such battery cells are also referred to as prismatic battery cells. These cells have a thickness direction and two faces oriented perpendicular to this thickness direction. The dimensions of the battery cells in the thickness direction are significantly smaller than those in the directions parallel to the faces. In this process, the battery cells are arranged into a battery stack such that adjacent battery cells in the stack face each other.It is possible to insert intermediate layers between the surface surfaces of adjacent battery cells, for example to compensate for tolerance differences and / or to compensate for volume changes of the electrochemical components of the battery cells, the so-called swelling of the battery cells, during the charging and discharging processes.

[0013] The method involves changing the relative orientation of each battery cell to its respective transport direction before arranging them into a battery stack. This ensures that, after the change, the battery cells are transported with their thickness parallel to their respective transport direction. This change in orientation allows the cells to be easily stacked, particularly by reducing the distances between them through a change in the transport speed, thus forming the battery stack.In other words, a stack can be easily formed by "piling up" the spaced-apart transported battery cells.

[0014] The task is solved in particular by ensuring that the change in the respective orientation of the battery cells relative to their respective transport direction takes place while maintaining a continuous transport movement.

[0015] In connection with the present invention, it has been shown that the feeding of the battery cells into the working area, where the arrangement of the battery cells into the battery stack takes place, can be carried out more quickly and efficiently if methods that involve an interruption of the conveying movement of the battery cells, and thus in particular clocked methods for changing the orientation of the battery cells, are avoided. Maintaining a continuous transport movement in this context means, in particular, that the transport movement of the battery cells is not stopped during the change in their respective relative orientation to their respective transport direction.However, the change in the respective orientation of the battery cells relative to their respective transport direction can be accompanied by a change in the speed and / or direction of the transport movement of the respective battery cell.

[0016] In this context, the transport direction of a battery cell refers specifically to the instantaneous transport direction of the battery cell, i.e., the transport direction of the battery cell at the respective point in time. This can change during the execution of the process with a battery cell if the battery cell undergoes changes of direction during its transport.

[0017] The process can provide that the battery cells are transported in a direction parallel to their surfaces before their orientation relative to their respective transport direction is changed. This transport of the battery cells is carried out, in particular, by transporting them one after the other on a conveying device, for example, a conveyor belt. With regard to the process steps preceding the arrangement of the battery cells into a battery stack, such an orientation of the battery cells during transport can be quite advantageous. Therefore, such an orientation of the battery cells during transport represents a beneficial starting point for changing the orientation of the battery cells relative to their respective transport direction.

[0018] The method involves rotating the battery cells around a vertical axis while changing their relative orientation to their respective transport direction. Compared to rotations around other axes, a rotation around a vertical axis is relatively easy to implement while maintaining continuous transport. This is particularly true when the actual transport movement takes place, at least substantially, in a horizontal plane. Therefore, rotating the battery cells around a vertical axis, especially relative to their respective transport direction, represents a practical way to change their orientation.

[0019] The method can, in particular, provide that the battery cells are rotated in different directions during the change of their respective relative orientation to their respective transport direction. The direction of rotation in which the individual battery cell is rotated can depend, in particular, on the desired spatial orientation of the battery cell poles after the change of their respective relative orientation to their respective transport direction. In this way, the method can be used to selectively achieve a desired spatial orientation of the battery cell poles in the battery stack. This, in turn, simplifies the process of achieving a desired electrical connection of the battery cells grouped together in the stack.In particular, this can be done regardless of the spatial orientation of its poles relative to its respective transport direction when the battery cell is transported before the change in orientation relative to its transport direction within the process. By selecting a suitable direction of rotation, the desired orientation can be achieved independently of the initial state. In particular, the angle of rotation required during the change of orientation can be minimized by rotating in the most advantageous direction.

[0020] The battery cells can be, in particular, battery cells whose poles are arranged on opposite narrow sides of the battery cell. Specifically, these are the two shorter narrow sides of the battery cell. In the process, the battery cells are transported in such a way that the opposite narrow sides, on which the poles are located, are vertically oriented. The possibility, described above, of selectively influencing the spatial orientation of the poles within the stack is particularly advantageous with such pole arrangements. Furthermore, the fact that the upward-facing side of the battery cells can be advantageously designed with such pole arrangements also offers advantages, for example, to facilitate gripping by a gripping device.

[0021] The method involves lifting the battery cells from a conveyor system before the change in their orientation relative to their respective transport direction, and then placing them onto the conveyor system or another conveyor system after the change. This allows the battery cells to be lifted and placed back onto the conveyor system or another conveyor system. This method has the advantage that both lifting and placing the battery cells can be performed while maintaining continuous transport movements, and it is possible to move the battery cells freely after lifting them from the conveyor system, in particular to rotate them around a vertical axis.

[0022] One advantage of such a method is that the respective battery cell only needs to be lifted a comparatively short distance between lifting and setting down to allow the change in its relative orientation to its transport direction. Preferably, in connection with the present method, the battery cell is lifted by no more than 5 millimeters. Since the battery cell only needs to be lifted a short distance, comparatively low accelerations are also necessary to enable the lifting and, in particular, the setting down of the respective battery cell in a sufficiently short time. Another advantage is that, should a lifted battery cell fall, for example, due to a malfunction, it will have traveled a comparatively short distance, thus preventing damage to the battery cell and / or a device onto which the battery cell falls.the risk of such damage is at least reduced.

[0023] In particular, the battery cells are preferably moved further in the transport direction between lifting and lowering by the manipulator device, which is used to lift and lower the battery cells, in such a way that the continuous transport movement is maintained. For example, the manipulator device can bridge a gap between the conveying devices involved.

[0024] The battery cells can be placed on the same conveyor system from which they were previously lifted. This method has the advantage that only one transport system is required.

[0025] Alternatively, the battery cells can be placed on a separate conveyor system – a different system than the one from which they were lifted. This allows for a simple change in the transport direction after the battery cell is placed, compared to the direction before it is lifted. This is particularly useful for accommodating spatial constraints during the process. For example, an excessively long production line, which includes conveyor systems, can be mitigated by "bending" the transport direction.

[0026] The conveying device and / or further conveying equipment could, for example, be a conveyor belt. Conveyor belts offer the advantage that the battery cells can be placed and transported on them in virtually any orientation. The distances between battery cells arranged on the conveying device can also be varied as needed, for example, to compensate for fluctuations in the cycle time of upstream and / or downstream process steps.

[0027] The manipulator device can have multiple gripping devices and use these devices to grasp the surfaces of the battery cells for lifting them. In particular, the manipulator device can grasp an upward-facing surface of each battery cell using a gripping device. Preferably, the manipulator device can have multiple gripping devices. This makes it possible to move multiple battery cells simultaneously using the gripping device. Grasping an upward-facing surface of the battery cell has the advantage, especially in connection with transport, that the gripping devices do not need to be moved between battery cells to grasp them. This reduces the risk of accidentally knocking over a neighboring battery cell when the manipulator device picks up a battery cell.

[0028] The gripping devices can engage the battery cells using a suction gripper. A suction gripper is a gripper that establishes a temporary mechanical connection with the battery cell by means of a generated vacuum. Such suction grippers offer the advantage that the battery cells only need to have a surface that is, at least substantially, flat for the suction gripper to engage them. These types of suction grippers are particularly advantageous when used with battery cells that have their poles on opposite narrow sides and are transported in such a way that these narrow sides are oriented vertically.Since in such cases a narrow side of the battery cells, on which no poles are provided, usually points upwards, a comparatively large area is then available on an upward-facing narrow side, which can be designed in a suitable way so that suction grippers can attack there.

[0029] The gripping device uses an adhesive gripper to attach to the battery cells. These grippers rely on van der Waals forces acting between the gripper and the battery cell. To generate the adhesive effect, the grippers can, for example, have a suitable microstructure on a surface with which they establish a temporary mechanical connection to the battery cell. This microstructure could, for instance, consist of numerous prongs extending from the surface towards the battery cell. Such adhesive grippers are also known as gecko grippers or adhesion grippers and are sold, for example, under the brand name "ADHESO".

[0030] The gripping devices may also each have a stripping and / or pressing device to detach the gripping device, in particular the suction gripper and / or adhesive gripper, from the battery cell.

[0031] The manipulator device can include a rotating gripper carrier by which the grippers are moved. Such a rotating gripper carrier can, for example, have the shape of a rotating wheel around whose circumference the grippers are arranged. The rotating gripper carrier moves the grippers, in particular, in a circular path projected onto a horizontal plane.

[0032] During the execution of the method, the rotating gripping device carrier is arranged relative to the transport device and / or the further transport device in such a way that the respective transport device, projected onto a horizontal plane, moves the battery cells tangentially towards or away from the circular path on which the gripping devices rotate. Where the path of movement of the battery cells conveyed by the respective transport device tangentially touches the circular path on which the gripping devices move, the connection of the gripping device and the lifting of the battery cell from the transport device and / or the setting down of the battery cell and the disconnection of the gripping device from the battery cell can be easily accomplished.This makes it possible for the battery cell to be conveyed in a continuous transport movement, which in the horizontal plane is represented as straight movement sections connected by a circular arc segment.

[0033] The peripheral speed at which the gripping devices move along their circular path corresponds in particular to the speed of the transport device and / or the further transport device. In this way, relative speeds between battery cells and gripping devices and / or between battery cells and transport device are largely reduced during lifting and / or setting down of the battery cells and / or when connecting the gripping devices to the battery cells and / or separating the gripping devices from the battery cells, which is advantageous for the lifting and / or setting down process.

[0034] Alternatively and / or additionally, the manipulator system can include a conveyor track along which the gripping devices move in a cycle. Gripping devices that can be moved independently of one another along the conveyor track can be used in this process. For example, the gripping devices can be designed as units that move along a rail system. Such moving units are also referred to as movers.

[0035] The method is preferably implemented such that, at the time the battery cells are lifted from the conveyor or the gripping device is connected to the battery cell, and / or when the battery cell is placed on a conveyor or when the gripping device is released from the battery cell, the path of movement of the respective gripping device runs parallel to the path of movement of the battery cell on the respective conveyor, i.e., the path of movement resulting from the conveying of the battery cell by the conveyor. The speed at which the gripping devices are moved along the conveyor corresponds, in particular at the time the battery cells are lifted from the conveyor or the gripping device is connected to the battery cell, and / or when the battery cell is placed on a conveyor.When the gripping device is detached from the battery cell, the speed of the transport device and / or the subsequent transport device is particularly affected. These measures can largely reduce relative speeds between the battery cells and the gripping devices and / or between the battery cells and the transport device during lifting and / or setting down of the battery cells and / or when connecting the gripping devices to the battery cells and / or separating the gripping devices from the battery cells, which is advantageous for the lifting and / or setting-down process.

[0036] The method may provide that the speed at which a battery cell is moved by the respective gripping device between lifting and placing is changed, for example to allow the speed of the transport device from which the battery cells are lifted to differ from the speed of another transport device on which the battery cells are placed, while still minimizing the relative speeds during lifting and placing.

[0037] Further practical embodiments of the invention are described below in connection with the drawings. They show: Fig. 1 a schematic representation of an exemplary process for the production of battery stacks, Fig. 2 a schematic representation of an exemplary method for the production of battery stacks according to a second embodiment.

[0038] In Fig. Figure 1 schematically illustrates a method for producing battery stacks 10. The battery stacks 10 are produced by grouping battery cells 12 together to form a battery stack 10. This can be done, as in the example shown, using a stacking device 14. This device can be designed, as schematically shown, as a conveyor system to which the battery cells 12 are transferred and thereby "accumulated" into battery stacks 10, in order to then be transported further in grouped stacks.

[0039] To enable this, the battery cells 12 must reach the stacking device 14 in a specific orientation. The battery cells 12 have an essentially cuboid shape, i.e., they have a thickness direction and two faces oriented perpendicular to that thickness direction. The dimensions of the battery cells 12 are significantly smaller in the thickness direction than in the directions parallel to the faces.

[0040] The method provides that the battery cells 12 are arranged in relation to the battery stack 10 such that adjacent battery cells 12 in the battery stack 10 face each other with their surfaces. To facilitate the simple formation of the battery stack 10, for example by "piling up" the battery cells 12 to form a battery stack 10 when transferring the battery cells 12 to a stacking device 14, as illustrated by way of example, it is advantageous if the battery cells 10 are fed to the stacking device 14 in the orientation shown in the figures, i.e., with their thickness direction oriented parallel to the transport direction T.

[0041] However, the upstream process steps may require that the battery cells 10 are first moved by means of a conveyor device 16 in a different orientation to the transport direction T, for example as in the Fig. 1 and Fig. 2 shown, with their thickness direction oriented perpendicular to the transport direction T, they are conveyed.

[0042] The in the Fig. 1 and Fig. The exemplary methods shown in the two examples therefore provide that the battery cells 12 undergo a change in their respective relative orientation to their respective transport direction T before being arranged into the battery stack 10. The change in orientation is such that, after this change in orientation, the battery cells are conveyed with their thickness direction parallel to their respective transport direction T.

[0043] The change in the respective orientation of the battery cells 12 relative to their respective transport direction T takes place while maintaining a continuous transport movement.

[0044] In the examples shown in the figures, the change in the respective orientation of the battery cells 12 relative to their respective transport direction T is achieved by a manipulation device 18 lifting the battery cells 12 to enable the change in the orientation of the respective battery cell 12 relative to their transport direction T.

[0045] This allows the battery cells 12 to be rotated about a vertical axis relative to their respective transport direction T in order to change their relative orientation to their respective transport direction T. This leads, in the case of the in Fig. As shown in the example 1, the spatial orientation of the battery cells 12 remains absolutely unchanged. However, due to the change in the transport direction T of the respective cell 12 when it is transferred by the manipulator device from the conveyor device 16 to another conveyor device 20, a change in the relative orientation of the respective battery cell 12 to its transport direction T takes place.As a result, the respective battery cell is initially conveyed on the conveyor 16 with its surface sides in parallel alignment to the transport direction T, and after the change of its orientation relative to its transport direction T, it is conveyed on the further conveyor 20 with its thickness direction parallel to its transport direction T, since the spatial orientation of the transport direction T of the respective battery cell 12 changes accordingly when it is transferred from the conveyor 16 to the conveyor 20.

[0046] To transfer the battery cells 12 from the conveyor 16 to the further conveyor 20, in the example shown, each battery cell 12 is lifted from the conveyor 16, on which it is transported before the change of its orientation relative to its transport direction T, and placed on the further conveyor 20 after the change of its orientation relative to its transport direction T. To enable this, the manipulator device 18 can have a rotating gripper carrier 22, as in the example shown. This can rotate in a horizontal plane, as in the example shown.

[0047] The manipulator device 18 can still be used as described in Fig. In the example shown, a plurality of gripping devices 24 are shown, which are moved on a circular path by means of the rotating gripping device carrier 22. The gripping device carriers 24, in turn, can be mounted on the gripping device carrier 22 so as to be rotatable about vertical axes, as in the example shown, in order to bring about the desired change in the relative orientation of the respective battery cell 12 relative to its transport direction T. This can mean, as in the example shown, that the absolute spatial orientation is maintained; however, in particular in the case of a different relative spatial arrangement of the conveyor device 16 and the further conveyor device 20 to each other, the absolute spatial orientation of the respective battery cell 12 can also change when it is moved by means of one of the gripping devices 24.

[0048] The gripping devices 24 can grip an upward-facing surface of the respective battery cell 12, as shown in the example. For this purpose, the gripping devices 24 are equipped with adhesive grippers.

[0049] The in Fig. The embodiment shown in 2 differs from the one in Fig. The embodiment shown in Figure 1 is distinguished by the design of the manipulator device 18 and the relative spatial arrangement of the conveying devices 16 and 20 to each other. In the embodiment shown in Figure 1, the manipulator device 18 is distinguished by the design of the manipulator device 18 and the relative spatial arrangement of the conveying devices 16 and 20. Fig. In the example shown, the spatial arrangement of the conveyor 16 relative to the other conveyor 20 is chosen such that the transport direction T of the battery cells 12 transported by the conveyor 16 is the same as the transport direction T of the battery cells 12 transported by the other conveyor 20. Accordingly, a change in the relative orientation of the battery cells 12 to their respective transport direction T also results in an absolute change in the absolute orientation of the respective battery cell 12.

[0050] The manipulator device 18 indicates in the Fig.In the example shown, a conveyor line 26 is depicted. Furthermore, the manipulator device has a plurality of gripping devices 24. The gripping devices 24 are moved in a circuit along the conveyor line 26. The speeds and / or distances between the gripping devices 24 can vary. In other words, the gripping devices 24 can be moved individually along the conveyor line 26. This can be achieved, for example, by a rail system that forms the conveyor line 26.

[0051] The features of the invention disclosed in the present description, the drawings, and the claims can be essential for realizing the invention in its various embodiments, both individually and in any combination. The invention can be varied within the scope of the claims and taking into account the knowledge of the person skilled in the art. Reference symbol list 10 battery stacks 12 battery cells 14 Stacking device 16 Funding institution 18 Manipulator device 20 other funding institutions 22 gripping device carriers 24 Gripping device 26 Conveyor route T Transport direction

Claims

[1] Method for producing battery stacks (10), wherein battery cells (12) having a basic shape that is at least substantially cuboid, according to which they have a thickness direction and two surface faces oriented perpendicular to the thickness direction, wherein the dimensions of the battery cells (12) in the thickness direction are substantially smaller than in the directions parallel to the surface faces, are arranged in a stack in which adjacent battery cells (12) are oriented with their surface faces towards each other, wherein, prior to arranging the battery cells (12) into the battery stack (10), a change in the respective relative orientation of the battery cells (12) to their respective transport direction (T) is carried out such that, after this change in their respective orientation, the battery cells (12) are transported with their thickness direction parallel to their respective transport direction (T), wherein the change in the respective orientation of the battery cells (12) relative to their respective transport direction (T) takes place while maintaining a continuous transport movement, wherein, to enable the change in their respective orientation relative to their respective transport direction (T), the battery cells (12) are lifted from a conveyor device (16) with which the battery cells (12) are transported by means of a manipulator device (18) before the change in their respective orientation relative to their respective transport direction (T) and, after the change in their respective orientation relative to their respective transport direction (T), are placed on the conveyor device (16) or on another conveyor device (20), characterized by, that the battery cells (12) are rotated about a vertical axis relative to their respective transport direction (T) during the change of their respective relative orientation to their transport direction (T), wherein the gripping devices (24) each engage the battery cells (12) by means of an adhesive gripper. [2] Method according to claim 1, characterized by , that the battery cells (12) are transported in a direction parallel to their surface sides before changing their respective orientation relative to their respective transport direction (T). [3] Method according to any of the preceding claims, characterized by , that the battery cells (12) are rotated in different directions during the change of their respective relative orientation to their respective transport direction (T), in particular to bring about a specific spatial orientation of the poles of the battery cells (12) in the battery stack (10). [4] Method according to any of the preceding claims, characterized by , that the manipulator device (18) has a plurality of gripping devices (24) and uses the gripping devices (24) to lift the battery cells (12) by gripping the surfaces of the battery cells (12). [5] Method according to claim 4, characterized by , that the gripping devices (24) attack upward-facing surfaces of the battery cells (12). [6] Method according to any of the preceding claims, characterized by , that the manipulator device (18) has a rotating gripping device carrier (22) by which the gripping devices (24) are moved. [7] Method according to any of the preceding claims, characterized by , that the manipulator device (18) has a conveyor section (26) along which the gripping devices (24) are moved in a cycle.

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