PRESSURE REGULATION SYSTEM AND METHOD FOR CONTROLLING THE PRESSURE OF A BATTERY CELL

Abstract

A pressure regulation system comprises a pressure plate arranged in an initial position relative to a battery cell, the battery cell being arranged in a housing, the pressure plate and the housing forming an enclosure, wherein an increase in the internal pressure of the battery cell causes an expansion force to be exerted on the pressure plate. The system includes a mechanical link attached to the pressure plate, the mechanical link being configured to translate the expansion force into an inverse force opposing the expansion force, and a rotatable component connected to the mechanical link, the rotatable component being configured to rotate from a first orientation to a second orientation based on a lateral movement of the mechanical link, thus allowing the pressure plate to move and increase the volume of the enclosure.

Description

INITIATIONThe present disclosure relates to battery systems and, more particularly, to regulating the pressure of battery cells of a battery system.U.S. Pat. No. 10,355,319 B1 discloses a pressure regulating system according to the preamble of claim 1. U.S. Pat. No. 2022 0 271 326 A1, DE 10 2019 007 363 A1 and DE 10 2018 117 414 A1 disclose related systems.Pouch battery cells are used in various applications, such as automotive applications (e.g., in electric and hybrid vehicles). Electric and hybrid vehicles include, for example, battery systems having battery packs that house multiple battery cells, including pouch cells such as lithium ion cells. During charging and discharging, as well as during aging of such cells, the pressure may change, which may adversely affect the charging and energy storage capability.It is an object of the invention to provide a pressure regulating system and a method for controlling a pressure of a battery cell that keep the pressure in the battery cells substantially constant over their entire operating duration.SUMMARYThe object is achieved by the features of the independent claims. Advantageous further developments are evident from the dependent claims.A pressure regulating system includes a pressure plate disposed in an initial position relative to a battery cell, the battery cell disposed in a housing, the pressure plate and the housing forming an enclosure, wherein an increase in an internal pressure of the battery cell causes an expansion force to be applied to the pressure plate. The system includes a mechanical linkage attached to the pressure plate, the mechanical linkage configured to translate the expansion force into a reverse force opposite the expansion force, and a rotatable component connected to the mechanical linkage, the rotatable component configured to rotate from a first orientation to a second orientation based on lateral movement of the mechanical linkage to allow the pressure plate to move and increase a volume of the enclosure.The mechanical linkage is configured to move laterally and rotate the rotatable component when the expansion force is greater than a threshold force.The rotatable component is a cam pivotally connected to an end of the mechanical linkage, the cam having a shape selected such that the pressure plate may define a first distance when the cam is in the first orientation and may define a second distance when the cam is in the second orientation.In addition to one or more of the features described herein, the cam has an eccentric center of gravity selected such that the cam is configured to return to the first orientation when the expansion force is less than the threshold force.In addition to one or more of the features described herein, the cam is configured to remain in contact with the pressure plate during rotation to continuously apply the reversing force as the battery cell expands.In addition to one or more of the features described herein, the mechanical linkage includes a pivot member having a first end and a second end, the first end being attached to a fixed pivot point on the pressure plate, and the fixed pivot point having a fixed position relative to the pressure plate.In addition to one or more of the features described herein, the mechanical linkage includes a link having third and fourth ends, the third end connected to the second end via a second pivot point, and the fourth end connected to the rotatable component.In addition to one or more of the features described herein, the pivot member includes a third pivot point between the first end and the second end, the third pivot point configured to move laterally along a guide member.In addition to one or more of the features described herein, the guide member includes a rail that causes the third pivot point to move in a lateral path and the fourth end to move both laterally and toward the pressure plate such that the rotatable component exerts the reversing force during rotation of the rotatable component.In another exemplary embodiment, a method of controlling a pressure of a battery cell includes receiving an expansion force on a pressure plate disposed in an initial position relative to the battery cell, the battery cell disposed in a housing, the pressure plate and the housing defining an enclosure, and the expansion force resulting from an increase in an internal pressure of the battery cell. The method includes regulating a pressure of the battery cell by a pressure regulating system including a mechanical connection attached to the pressure plate, the mechanical connection connected to a rotatable component, wherein regulating the pressure includes translating the expansion force into a reverse force based on lateral movement of the mechanical connection, the reverse force configured to oppose the expansion force, and based on the expansion force exceeding a threshold force, causing the mechanical connection to move laterally and rotating the rotatable component from a first orientation to a second orientation to allow the pressure plate to move and increase a volume of the enclosure.The rotatable component is a cam pivotally connected to an end of the mechanical linkage, the cam having a shape selected such that the pressure plate may define a first distance when the cam is in the first orientation and may define a second distance when the cam is in the second orientation.In addition to one or more of the features described herein, the cam has an eccentric center of gravity selected such that the cam is configured to return to the first orientation when the expansion force is less than the threshold force.In addition to one or more of the features described herein, during rotation, the cam remains in contact with the pressure plate to continuously apply the reversing force as the battery cell expands.In addition to one or more of the features described herein, the mechanical linkage includes a pivot member having a first end and a second end, the first end being attached to a fixed pivot point on the pressure plate and the fixed pivot point having a fixed position relative to the pressure plate, and the mechanical linkage includes a link member having third and fourth ends, the third end being connected to the second end via a second pivot point and the fourth end being connected to the rotatable component.In addition to one or more of the features described herein, the pivot member includes a third pivot point between the first end and the second end, the third pivot point configured to move laterally along a guide member.In addition to one or more of the features described herein, the guide member includes a rail that causes the third pivot point to move along a lateral path and the fourth end to move both laterally and toward the pressure plate such that the rotatable component exerts the inverting force during rotation.In yet another example embodiment, a vehicle system includes a battery system connected to an electric motor of a vehicle, the battery system including a battery cell disposed in a housing. The vehicle system also includes a pressure regulating system having a pressure plate disposed in an initial position relative to a battery cell, the battery cell disposed in a housing, the pressure plate and the housing forming an enclosure, wherein an increase in an internal pressure of the battery cell causes an expansion force to be applied to the pressure plate. The pressure regulation system includes a mechanical linkage attached to the pressure plate, the mechanical linkage configured to translate the expansion force into a reverse force opposite the expansion force, and a rotatable component connected to the mechanical linkage, the rotatable component configured to rotate from a first orientation to a second orientation based on lateral movement of the mechanical linkage to allow the pressure plate to move and increase a volume of the enclosure.In addition to one or more of the features described herein, the mechanical linkage is configured to move laterally and rotate the rotatable component when the expansion force is greater than a threshold force.In addition to one or more of the features described herein, the rotatable component is a cam connected to an end of the mechanical linkage via a pivot, the cam having a shape selected such that the pressure plate may define a first distance when the cam is in the first orientation and may define a second distance when the cam is in the second orientation, the cam configured to remain in contact with the pressure plate during rotation to continuously apply the reversing force as the battery cell expands.In addition to one or more of the features described herein, the cam has an eccentric center of gravity selected such that the cam is configured to return to the first orientation when the expansion force is less than the threshold force.The above features and advantages, as well as other features and advantages of the disclosure, will be readily apparent from the following detailed description when taken in conjunction with the accompanying drawings.BRIEF DESCRIPTION OF THE DRAWINGSOther features, advantages and details are included, by way of example only, in the following detailed description, which relates to the drawings, in which: FIG. 1 shows an energy storage system including a housing holding one or more battery cells and a pressure regulation system according to an example embodiment; FIGS. 2A-2C are force diagrams illustrating various forces generated during operation by a linkage mechanism in cooperation with the biasing system of FIG. 1, according to an example embodiment; FIGS. 3A and 3B show an energy storage system including a pressure regulation system including one or more mechanical connections, each mechanical connection connected to a rotatable component, according to an example embodiment; FIG. 4 shows an energy storage system including a pressure regulation system including one or more mechanical connections, each mechanical connection connected to a rotatable component, according to an example embodiment; FIGS. 5A and 5B show an energy storage system including a pressure regulation system including one or more mechanical connections and a biasing system including one or more biasing members, according to an example embodiment; FIG. 6 illustrates an energy storage system including a pressure regulation system including one or more mechanical connections and a controllable biasing system including one or more biasing members, according to an example embodiment; FIGS. 7A and 7B show an adjustment device of the biasing system of FIG. 6 according to an example embodiment; FIG. 8 is a flowchart describing a method for regulating pressure in a battery system according to an exemplary embodiment; and FIG. 9 illustrates a computer system according to an example embodiment.DETAILED DESCRIPTIONThe following description is merely exemplary in nature. It should be understood that throughout the drawings, corresponding reference numerals designate like or corresponding parts and features.According to one or more example embodiments, methods, apparatus, and systems for controlling pressure in battery assemblies and battery systems are provided. One embodiment of a pressure regulating system includes a pressure plate disposed in a housing of a battery assembly (e.g., a battery pack or a battery module) and movable in response to an expansion force generated by the expansion of a battery cell or cells in the housing. The pressure regulating system also includes one or more mechanical compounds that translate a portion of the expansion force into a reactive force or reverse force to maintain or achieve a desired pressure in the battery cell or cells.In one embodiment, a mechanical linkage includes a first elongate member (referred to as a "pivot member") and a second elongate member (referred to as a "link member"). The pivot element is attached, for example, at one end to the pressure plate by a pin and at another end to one end of the connecting element by another pin. The pivot member is also attached to a pivot point between the ends of the pivot member. The pivot point may be fixedly coupled to the housing or coupled to a rail that allows lateral movement of the pivot point. When an expansion force is applied to the pressure plate, movement of the pressure plate causes an end of the link to move laterally (i.e., along the pressure plate and / or in a direction orthogonal to the direction of the expansion force).Lateral movement of the linkage may be restricted by restricting lateral movement to a selected lateral distance. The restriction of lateral movement may be achieved by a stationary stop component mounted on the pressure plate or a component mounted on the connecting element.When the lateral movement is restricted, the lateral force exerted by the connecting element is translated into a reactive force or reverse force that is proportional to the expansion force. Embodiments of the pressure regulation may be configured to generate a reverse force that is directly proportional to the expansion force. The portion of the expansion force translated into the return force may be selected by selecting the parameters of a link mechanism, such as the length of the pivot member and link member.In one embodiment, the lateral movement is constrained by a rotatable component that is activated by the lateral movement to rotate along the pressure plate. Rotation of the rotatable component may reduce the distance between the pressure plate and the housing such that the pressure plate may move upward and provide space for expansion of a battery cell. For example, each link is coupled to a cam resting on the pressure plate and defining an initial distance when the link mechanism is in an initial state. When sufficient expansion force (threshold expansion force) is applied, the link moves laterally, thereby rotating the cam and decreasing the distance between the pressure plate and the housing.In one embodiment, the pressure regulating system includes a biasing system that cooperates with the mechanical link or links and the rotatable components to establish a desired threshold expansion force. The biasing system includes at least one biasing member that can be selected to control the amount of lateral force that must be applied to rotate a cam, and thereby calibrate the pressure regulating system to a desired threshold expansion force (threshold force).The biasing system includes, for example, a laterally extending spring configured to be coupled to a cam of a mechanical linkage, enabling control of the threshold force. The spring is operatively connected to the cam or link and exerts a spring force that resists lateral movement of the link. The magnitude of the spring force may be calibrated or adjusted, for example, by selecting a spring having an appropriate spring constant and / or by incorporating a spring adjuster that may be actuated to change the spring force.The embodiments described herein provide numerous advantages and technical effects. The embodiments provide improved battery functionality by maintaining constant force on the battery cells during the lifetime thereof, thereby effectively controlling pressure and avoiding adverse effects such as dendritic growth. Moreover, embodiments provide a mechanism that automatically adjusts to allow expansion and reduce excessive pressure that may occur due to the expansion.FIG. 1 shows an embodiment of an energy storage device or system 10 that includes a battery module 12 that houses a set (i.e., one or more) of battery cells 14. Each battery cell 14 may be any rechargeable cell type, such as a lithium-based cell (e.g., lithium ions, lithium metal (LMB), etc.). Each cell 14 is, for example, a pouch type lithium ion cell.The module 12 includes a housing 16 in which one or more battery cells 14 are disposed. When multiple cells are housed, they may be stacked as shown with adjacent cells 14 separated by a support plate 18. It should be noted that the embodiments described herein are not limited to the type or dimensions of the housing 16, the type, dimensions or number of cells shown, or the type of cells shown.The battery module 12 includes or is coupled to a pressure regulating system 20 configured to automatically control the pressure in the cells 14. The pressure regulating system 20 includes a pressure plate 22 disposed above the cells 14. The pressure plate 22 has a default position that may be on or near a surface of the top cell 14, such as a position where the pressure plate 22 contacts a cell 14 (e.g., rests on top cell 14). Alternatively, as shown in FIG. 1, the default position may define a distance or gap that allows some cell expansion before pressure equalization or pressure regulation is triggered. It should be noted that the pressure plate 22 may be disposed at any position or location (e.g., below the battery cells 14) such that expansion of the battery cells causes movement of the pressure plate 22.A pressure balancing device is disposed on or otherwise connected to the pressure plate 22 and configured to apply a reactive force to the pressure plate 22 to compensate for the expansion of the cells 14 and maintain the cells 14 at a desired pressure (or within a desired pressure range).The pressure balancing device includes a set (i.e., one or more) of mechanical connections 24 that translate an expansion force on the pressure plate 22 into a reverse force (i.e., in a direction opposite the expansion force). For example, as the cells 14 expand and exert the expansion force in an upward direction on the pressure plate 22, the mechanical connections 24 exert a proportional downward force. Each link 24 may be calibrated to generate a downward force that maintains a constant selected pressure on the cells 14 as they expand.As shown in FIG. 1, the pressure balancing device includes two connections 24 at opposite ends of the pressure plate 22, and the pressure plate 22 is oriented such that a surface 23 facing the cells 14 defines a plane that is orthogonal to the direction of expansion. The expansion direction is, for example, along a z-axis (i.e., in a z-direction), and the surface 23 is parallel to a plane defined by an x-axis and a y-axis (x-y plane).Each mechanical linkage 24 includes a first member 26 ("pivot member") attached to the pressure plate 22 via a pivot point P 1. One end of the pivot member 26 is connected to the pivot point P 1, and the pivot point P 1 has a fixed position with respect to the pressure plate 22. Another end of the pivot member 26 is attached to a pivot point P2 at one end of a link member 28.The pivot member 26 also includes a pivot point P 0 located between the ends (e.g., at a central location equidistant from the ends of the pivot member 26). The pivot member 26 rotates about the pivot point P 0 when the link mechanism moves laterally.When the internal pressure of a battery cell increases, a force caused by expansion (referred to as "expansion force" as F e ) may be applied to the pressure plate 22 in the upward or vertical direction (in the z direction). An end 30 of the linkage 28 is coupled to the pressure plate 22 such that the mechanical linkage 24 translates a portion of the expansion force into a reactive force (also referred to as a "reverse force" labeled F r ). The reversing force F r acts in a direction opposite to the expanding force F e and is a selected portion of the expanding force.When the expansion force F e is sufficient to move the pressure plate 22, the pivot member 26 rotates about the pivot point P 0 which, in turn, causes the end 30 of the linkage member 28 to move laterally (e.g., in the x-direction) or exert a lateral force toward the center of the pressure plate 22. A "lateral" direction may be a direction (e.g., in the x-y plane) orthogonal to a direction of the expansion force or a direction along a surface of the pressure plate 22.The lateral movement is restricted, such that the lateral force exerted by the connection 24 is deflected in the direction of the battery cells 14. This may be achieved, for example, by a stop component 32 which may be an elevated structure that resists lateral movement of the connecting elements 28. When a connecting member 28 engages the stop component 32 or other boundary, the opposing lateral forces cause the return force F to be applied in r to the cell 14. The reversing force F r is proportional to the expansion force F e. The parameters of the mechanical connections 24 may be selected to calibrate the mechanical connections 24 to achieve a desired proportionality of the reverse force. Examples of such parameters include the length of the pivot member 26 and the link member 28, the height of the pivot point P 1, a location of the pivot point P 2, a location of the stop component 32, and others.Lateral movement may be limited in various ways. Lateral movement is restricted, for example, by a rotatable component, as described above. Additionally or alternatively, a biasing system may be present to adjust or calibrate the pressure regulating system 20.FIGS. 2A-2C are force diagrams illustrating aspects of force transmission using a mechanical connection 24 and a resistive component (not shown). The resistive element may be the stop component 32 or a cam 40 (see FIGS. 3A and 3B ). FIGS. 2A-2C also illustrate aspects of calculating forces and selecting parameters for the linkage mechanism to achieve a desired return force.In these diagrams, l 1 is a length in the x-z plane from point P1 to point P0, l 2 is a length from point P0 to point P2, and l 3 is a length from point P2 to point P3. The pivot member 26 defines an angle θ 1 with respect to the x-axis (or a direction of lateral movement of the end 30), and the link member 28 defines an angle θ 3 with respect to the x-axis.As shown in FIG. 2A, when a force F 1( the expansion force) is applied vertically (in the z direction or parallel to the expansion direction) to the pressure plate 22, the pivot member 26 rotates about the pivot point P 0 thereby applying a force F 2 to the link member 28, which in turn causes the link member 28 to move in the x direction and generate a lateral force F 3.As shown in FIG. 2B, the connector 28 moves a lateral distance d 3 and the connector 28 presses against a resistive element. The resistance component exerts an opposing lateral force f l.When the link mechanism 24 is in a stable state, the link mechanism 24 does not move. The pivot member 26 and the link member 28 may be considered a rigid body having a pivot point at point P 0 as illustrated in FIG. 2C. In this state, the link mechanism 24 exerts a force F 4. The force F 4 has a normal component F 4N that represents the reverse force applied to the battery cell 14.In the steady state, the total torque is zero and can therefore be represented as follows: where l 4 is a length from point P0to P3(FIG. 2C ). Therefore, the reason is that it is possible to obtain the sameThe normal component F 4N, i.e., the reversing force, can be calculated on the following basis:The length l 4 varies depending on d 3 and the length of the pivot member 26 and the link member 28. The system 20 may also be calibrated from the positions of points P 0 and P 1 to affect the reversing force.FIGS. 3A and 3B show an embodiment of the pressure regulating system 20 that includes a rotatable component connected to each mechanical link 24. The rotatable component is configured to rotate in response to the lateral movement of the link 24 and allow the pressure plate 22 to move and provide additional space for the expansion of a battery cell 14. In this manner, the pressure regulating system 20 automatically responds to an increase in internal pressure and thus provides a volume buffer.In this embodiment, the rotatable component is a cam 40, which may be any body that can be rotated and remains engaged with the pressure plate 22 during rotation. The cam 40 has a non-circular shape, such as a pear or drop shape, as shown in FIGS. 3A and 3B. The shape may be any suitable shape such that the height h of the cam 40 changes by the rotation of the cam 40.FIG. 3A shows the pressure regulating system 20 in an initial state in which the cam 40 of each mechanical linkage 24 is in a first orientation. In the first orientation, the cam 40 defines a distance D between an upper surface 27 of the pressure plate 22 and an upper portion of the housing 16, and the pressure plate 22 defines a volume with the housing 16.FIG. 3B shows the pressure regulating system 20 in an activated state. The activated state is triggered when the expansion force F e exceeds the threshold force. When activated, the cam 40 has rotated to a second orientation in which the height h is decreased so that the pressure plate 22 may move upward and decrease the distance D and allow for an increase in volume to allow for expansion of the battery cell 14.The cam 40 is connected to the end 30 via a pin 42 or other linkage mechanism that allows the cam 40 to rotate about the end 30. For example, as shown, pin 42 is disposed at or near a relatively wide end of cam 40.In one embodiment, the cam 40 has a center of gravity 44 that is eccentrically disposed to aid in returning the cam 40 to the first orientation when the internal pressure of the battery cell 14 decreases and the expansion force falls below the threshold. The center of gravity 44 may be determined, for example, by increasing the thickness of the cam 40 (e.g., along the y-axis) near the narrower end of the cam 40, or by using a higher density material or inserting near the narrower end.In one embodiment, the pressure regulating system 20 also includes a mechanical guide or rail 46 that limits the movement of the pivot point P 0 to a lateral travel path. The rail 46 includes, for example, elongated members that can retain a pin 47 or other component at the pivot point P 0. The rail 46 prevents or otherwise defines a path for the pivot point P 0 to move vertically such that the pivot member 26 forces the link member 28 to laterally and vertically translate the cam 40 as the cam 40 rotates. In this way, a reverse force is applied to the battery cell 14 as the battery cell 14 expands and moves the pressure plate 22 upward. The rail 46 includes an end component or surface 50 that prevents the pivot point P 0 from moving beyond a desired position toward a side wall of the housing 16.The pressure regulation system 20 may include additional functions or components to facilitate the transition between the initial state and the activated state. In one embodiment, the pressure plate 22 includes or is attached to an engagement surface 48 configured to generate sufficient friction to prevent the cam 40 from sliding. The engagement surface 48 is, for example, a portion of the raised roughness top surface 27 or a separate plate or component attached to the surface 27.Additionally or alternatively, the surface of the cam 40 may have a roughness that provides friction. In another example, the surfaces of the cam 40 and the engagement surface 48 may include features such as grooves or serrations that allow the cam 40 to engage the pressure plate and rotate without sliding.The rail 46 may define a linear or non-linear path. For example, as shown in FIG. 4, the rail 46 may be a curved rail. The curvature of the rail 46 may be selected such that the end of the link 28 moves in a circular or arcuate path to facilitate rotation of the cam 40. The curvature may also be selected to affect the magnitude of the reverse force F r exerted by a linkage mechanism 24 as the pressure plate 22 is forced upward by the cell expansion.It should be noted that the embodiments are not limited to the number and location of the mechanical connections shown herein. The pressure regulating system 20 may include, for example, a linkage mechanism 24 on one side of the pressure plate 22. Moreover, more than one connecting mechanism 24 can be arranged in a row in the y-direction.In one embodiment, the pressure regulation system 20 includes a biasing system that provides one or more components configured to control the magnitude of the return force F r (i.e., control a portion of the expansion force F e that is diverted to the cell 14). The biasing system may be a passive or active system that may be configured to maintain and / or adjust a desired ratio.The biasing system may also be configured to control the amount of expansion force (i.e., threshold force) required to cause the link mechanism or mechanisms 24 to transition to the activated state.For example, as shown in FIGS. 5A and 5B, the pressure regulating system 20 includes a stop component 60 that is part of or attached to the pressure plate 22. A laterally extending spring 62 is provided that may be coupled to a linkage mechanism 24 to resist lateral movement of a linkage 28 and rotation of the cam 40. Each spring 62 exerts a biasing force that opposes the lateral movement.FIG. 5A shows the pressure plate 22 in an initial or standard position in which a standard force F d is applied to the cell 14. Each spring 62 is connected or attached to the stop component 60 at one end of the spring 62. The other end of the spring 62 is laterally spaced from the stop component 60 and is configured to engage a corresponding cam 40 and apply a biasing force that resists rotation.The biasing force depends on a spring constant k of the spring 62. As the cell 14 expands and exerts an expansion force on the pressure plate 22, the upward movement of the pressure plate 22 causes each pivot 24 to rotate about the pivot point P 0 and the pivot point P 0 to move along the rail 46, which in turn causes the link 28 to move laterally and rotate the cam 40. The rotation of the cam 40 compresses the spring 62, as shown in FIG. 5B. By selecting an appropriate spring constant, the lateral force required for the cam to rotate and the corresponding expansion force threshold may be selected.In one embodiment, the pressure regulating system 20 includes a bias control system that can be actively controlled at any time to change the ratio between expansion and return forces. The biasing control system may also be used to compress or relieve one or both biasing members to adjust the expansion force threshold.FIG. 6 shows an embodiment of the pressure regulating system 20 with a biasing member adjustment system 80. The adjustment system 80 includes an adjustment device referred to as a spring adjuster 82. The spring adjuster 82 is coupled to the springs 62 and is controllable to increase or decrease spring compression and thereby control the spring force (i.e., the magnitude of the spring force due to a particular lateral movement).In one embodiment, the spring adjuster 82 includes a stationary pinion 84 coupled to at least one rack 86 (or other linear actuator). Each rack 86 is attached to or otherwise engageable with a respective spring to adjust the spring force. For example, each rack 86 is attached at one end thereof to an interface component 88 (e.g., a plate or disk) that engages a corresponding spring 62.The pinion is coupled to an actuator 90, such as a low power motor, that is operable to rotate the pinion 84 to move the racks 86 and compress or relieve the springs 62. The actuator 90 may be manually controlled by an operator or via a controller 92 or other processing device.When the return force F r is to be adjusted (e.g., to maintain a constant pressure as conditions such as temperature, pressure, or threshold force change), the actuator 90 is controlled to rotate the pinion 84 and actuate the racks 86. The pinion 84 may be rotated clockwise to move the rack 86 outward and compress the springs 62, thereby increasing the threshold force. To relieve the springs 62 and thus reduce the threshold force, the pinion 84 may be rotated counterclockwise.Embodiments are not limited to the configuration shown in FIG. 6. Embodiments may include multiple spring force adjusters synchronously controlled by a single motor. In other embodiments, a plurality of independent spring force adjusters are provided, each spring force adjuster being independently controlled.FIGS. 7A and 7B show an example in which the biasing system 80 comprises two independently controllable spring adjusters 82 aand 82 b. Each spring adjuster is coupled to a different spring or biasing device and has its own motor. FIG. 7A shows the biasing system in a first state in which the pressure on the springs 62 is relatively low, and FIG. 7B shows a state in which the spring adjusters 82 aand 82 bare both operated to compress their respective springs. Because each spring adjuster is independently controllable, a different amount of compression may be adjusted (e.g., spring adjusters 82 aand 82 bare controlled such that one of springs 62 has a different compression than an opposing spring 62).FIG. 8 illustrates an embodiment of a method 100 for regulating pressure in a battery assembly. Aspects of method 100, such as adjustment of a biasing system, may be performed by one or more processors.The method 100 includes a series of steps or steps represented by blocks 101- 103. The method 100 is not limited to the number or order of steps included therein, as some of the steps represented by blocks 101- 103 may be performed in an order other than that described below, or fewer than all of the steps may be performed.Aspects of the method 100 are discussed for illustrative purposes in connection with the energy storage device 10 and the pressure regulation system 20 of FIGS. 2A and 2B illustrated in FIG. 1. The method 100 is not limited thereto and may be used with any type of battery cell and system having connections that reverse forces as described herein.At block 101, a battery assembly is assembled or manufactured. The battery assembly may be a battery module, such as module 12, having one or more battery cells. These cells may be lithium metal pouch cells or any other cell undergoing expansion. The manufacture of the battery assembly includes disposing a pressure regulating system such as the pressure regulating system of FIGS. 3A and 3B.At block 102, the battery assembly is operated. The battery module 12 is, for example, a battery pack of a vehicle and supplies electric power to one or more electric motors of the vehicle.If the battery cells expand during operation (or between operations), the pressure regulating system 20 controls the pressure of one or more battery cells of the battery assembly at block 103. This controlling includes applying a proportional reverse force toward the battery cell(s) to balance the expansion force and maintain a desired pressure or pressure range. For example, as the battery cells 14 expand, the mechanical connections 24 and the cams 40 redirect a portion of the expansion force F e as the return force F r.The pressure plate 22 exerts, for example, a standard or initial reverse force F d to maintain an initial pressure in the battery cell 14. As the battery cell 14 cycles, a pressure increase causes the expansion force F e, and the pressure regulation system 20 responds by providing the return force F r thereto. When the expansion force F e reaches a certain threshold, the linkage mechanisms 24 move laterally and rotate their respective cams 40 so that the pressure plate 22 can be pushed up, and provide additional volume to accommodate expansion and reduce pressure. When a spring adjuster 82 is present, the controlling includes operating the actuator 90 to adjust the spring force exerted in response to movement of a linkage mechanism 24.This pressure control provides the additional volume if needed to avoid adverse effects such as separator breakage, dendritic growth, and possible internal shorts. If the expansion force is below the threshold, the pressure controller may also apply a reverse force to maintain a desired pressure range, which may have positive effects, such as preventing dendritic growth.FIG. 9 illustrates aspects of an embodiment of a computer system 140 that may perform various aspects of the embodiments described herein. The computer system 140 includes at least one processing device 142 that generally includes one or more processors for performing aspects of the image acquisition and analysis methods described herein.Components of computer system 140 include processing device 142 (such as one or more processors or processing units), memory 144, and bus 146 that couples various system components including system memory 144 to processing device 142. System memory 144 may be a non-transitory computer readable medium and may include a variety of computer readable media. These media may be any available media that can be accessed by the processing device 142, including both volatile and nonvolatile media, and removable and non-removable media.System memory 144 includes, for example, non-volatile memory 148, such as a hard disk, and may also include volatile memory 150, such as random access memory (RAM) and / or cache memory. Computer system 140 may further include other removable / non-removable, volatile / non-volatile computer system storage media.System memory 144 may include at least one program product having a set of program modules (e.g., at least one) configured to perform the functions of the embodiments described herein. System memory 144 stores, for example, various program modules that generally perform the functions and / or methods of the embodiments described herein. One or more modules 152 may be present to perform functions related to monitoring battery systems. An image analysis module 154 may be for controlling aspects of pressure regulation, such as for controlling the actuator of the spring adjuster as described herein. The system 140 is not limited thereto, as other modules may be present. As used herein, the term module refers to processing circuitry that may include an application specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group), and memory that executes one or more software or firmware programs, combinatorial logic circuitry, and / or other suitable components that provide the described function.The processing device 142 may also communicate with one or more external devices 156, such as a keyboard, a pointing device, and / or other devices (e.g., a network card, a modem, etc.) that enable the processing device 142 to communicate with one or more other computing devices. Communication with various devices may be via input / output (I / O) interfaces 164 and 165.The processing device 142 may also communicate with one or more networks 166, such as a local area network (LAN), a general wide area network (WAN), a bus network, and / or a public network (e.g., the Internet), via a network adapter 168. It should be understood that other hardware and / or software components may also be used in conjunction with computer system 40, although not shown. Examples of such systems include microcode, device drivers, redundant processing units, external disk arrays, RAID systems, data archive systems, etc.The terms "a" and "an" do not mean a quantity limitation, but rather denote the presence of at least one of the elements mentioned. The term "or" means "and / or" unless the context clearly indicates otherwise. Throughout this specification, when "one aspect" is mentioned, it means that a particular element (e.g., feature, structure, step, or characteristic) described in connection with the aspect is included in at least one of the aspects described herein and may or may not be present in other aspects. It is understood that the described elements may be combined in any suitable manner in the various aspects.When an element such as a layer, film, region or substrate is referred to as being "on" another element, it may be directly on the other element or intervening elements may also be present. In contrast, there are no intervening elements when an element is referred to as being "directly on" another element.Unless otherwise specified herein, all testing standards are the latest standard in effect on the filing date of this application or, if a priority is claimed, on the filing date of the earliest priority application in which the testing standard appears.Unless defined otherwise, the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

Claims

A pressure regulating system (20) comprising: a pressure plate (22) disposed in an initial position relative to a battery cell (14), the battery cell (14) disposed in a housing (16), the pressure plate (22) and the housing (16) forming an enclosure, wherein an increase in an internal pressure of the battery cell (14) causes an expansion force (F e) to be applied to the pressure plate (22); a mechanical linkage (24) attached to the pressure plate (22), the mechanical linkage (24) configured to translate the expansion force (F e) into a reverse force (F r) opposite the expansion force (F e) ; and a rotatable component, which is connected to the mechanical link (24), wherein the rotatable component is configured to rotate from a first orientation to a second orientation based on lateral movement of the mechanical link (24) to allow the pressure plate (22) to move and increase a volume of the enclosure, wherein the mechanical link (24) is configured to move laterally and to rotate the rotatable component when the expansion force (F e) is greater than a threshold force, characterized in that the rotatable component is a cam (40) connected to an end of the mechanical link (24) via a pivot, wherein the cam (40) has a shape selected such that the pressure plate (22) can define a first distance when the cam (40) is in the first orientation and can define a second distance, when the cam (40) is in the second orientation.The pressure regulating system (20) of claim 1, wherein the cam (40) has an eccentric center of gravity selected such that the cam (40) is configured to return to the first orientation when the expansion force (F e) is less than the threshold force.The pressure regulating system (20) according to claim 1, wherein the cam (40) is configured to remain in contact with the pressure plate (22) during the rotation to continuously exert the reversing force (F r) as the battery cell (14) expands.The pressure regulating system (20) of claim 1, wherein the mechanical linkage (24) comprises a pivot member (26) having a first end and a second end, the first end being attached to a fixed pivot point on the pressure plate (22), and the fixed pivot point having a fixed position relative to the pressure plate (22).The pressure regulating system (20) of claim 4, wherein the mechanical linkage (24) comprises a link (28) having third and fourth ends, the third end being connected to the second end via a second pivot point, and the fourth end being connected to the rotatable component.The pressure regulating system (20) of claim 5, wherein the pivot member (26) comprises a third pivot point between the first end and the second end, the third pivot point configured to move laterally along a guide member.The pressure regulating system (20) of claim 6, wherein the guide member comprises a rail (46) that causes the third pivot point to move on a lateral path and the fourth end to move both laterally and toward the pressure plate (22) such that the rotatable component exerts the reversing force (F r) during rotation of the rotatable component.A method of controlling a pressure of a battery cell (14), comprising: receiving an expansion force (F e) on a pressure plate (22) disposed in an initial position relative to the battery cell (14), wherein the battery cell (14) is disposed in a housing (16), the pressure plate (22) and the housing (16) define an enclosure, and the expansion force (F e) results from an increase in an internal pressure of the battery cell (14); Regulating a pressure of the battery cell (14) by a pressure regulating system (20) according to at least one of the preceding claims, wherein regulating the pressure comprises: translating the expansion force (F e) into a reverse force (F r) based on lateral movement of the mechanical linkage (24), wherein the reverse force (F r) is configured to counteract the expansion force (F e) ; and based on the expansion force (F e) exceeding a threshold force, causing the mechanical linkage (24) to move laterally and rotating the rotatable component from a first orientation to a second orientation to allow the pressure plate (22) to move and increase the volume of the enclosure.

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