fuel cells

Abstract

The fuel cell (1) comprises a bipolar plate (201), in particular a plurality of bipolar plates (210), and / or a connection means (9), in particular a plurality of connection means (9), wherein the bipolar plate (210) extends in a width direction (B) and a longitudinal direction (L), the longitudinal direction (L) and the width direction (B) being in particular perpendicular to one another, the bipolar plate (210) has a plurality of openings (240), the openings (240) have an outer contour, the outer contour of the openings (240) being formed in particular by a mounting opening (242) and at least one flow opening (244) in each case, the mounting opening (242) advantageously forming a circular segment-shaped part of the outer contour of the opening (240), and the mounting opening (242) or the opening (240) being designed to receive the connection means (9) or the connection means (9).

Description

[Technical Field]

[0001] The present invention relates to fuel cells.

[0002] Fuel cells are already known from the prior art. They are used to generate an electric current or to supply energy, in particular by using a reaction that releases electrons. Various fluids can be used as fuel, for example hydrogen. However, a problem with known systems is that a fuel cell consists of several cells separated from each other by bipolar plates. To achieve a compact design, these cells are usually arranged in a stack and covered at the ends by end plates. The cells are usually fixed to each other and to the end plates by external connection means. However, this exposes the bipolar plates and end plates to high bending stresses and / or results in high installation space requirements.

[0003] It is therefore an object of the present invention to provide a space-saving arrangement that allows the components of a fuel cell to be securely fixed.

[0004] This problem is solved by a fuel cell according to claim 1 and a use according to claim 15. Further advantages, features and embodiments are set out in the dependent claims, the embodiments and the figures.

[0005] The present invention relates to a fuel cell. The fuel cell comprises, in particular, bipolar plates, in particular a plurality of bipolar plates, and / or in particular connecting means, in particular a plurality of connecting means, the bipolar plates extending in a width direction and a longitudinal direction, the longitudinal direction and the width direction being in particular perpendicular to each other, the bipolar plates having a plurality of openings, the openings having an outer contour, the outer contour of the openings being in particular formed in each case by a mounting opening and at least one flow opening, the mounting opening advantageously forming a circular segment-shaped portion of the outer contour of the opening, the mounting opening or said opening or one of said openings being designed to receive a connecting means. The fuel cell is used to convert one form of energy, usually chemically bound, into another form, in particular electrical energy. The fuel cell comprises bipolar plates and / or connecting means. The connecting means will be explained in more detail below. However, it is advantageous that at least one connecting means, preferably a plurality of connecting means, and most preferably all connecting means, extend through the bipolar plates or through some openings or all bipolar plates. In other words, the bipolar plate or several bipolar plates surround or enclose the connection means. This allows a particularly compact construction to be created. The bipolar plates can serve to form or form part of a fuel cell. The bipolar plates extend in a width direction and a longitudinal direction, the longitudinal direction and the width direction being particularly perpendicular to each other, and the bipolar plates have a plurality of openings, the openings having an outer contour, the outer contour of the openings in each case being formed by a mounting opening and at least one flow opening, the mounting opening forming a circular segment-shaped portion of the outer contour of the opening, and the mounting opening being designed to receive the connection means. The bipolar plates can be part of and / or arranged or used in a fuel cell. In particular, an MEA is arranged in each case between two bipolar plates. The MEA in the sense of the present invention should be understood as mounting the membrane electrodes.Thus, in order to limit the suction volume of the MEA, the bipolar plates serve to at least partially simultaneously conduct fuel, in particular hydrogen, and / or oxygen and / or combustion products, in particular fluids such as water or steam, from and / or to the MEA. Furthermore, the bipolar plates may be used, in particular, to conduct electrons. In particular, the bipolar plates are formed at least partially from an electrically conductive material and / or plastic and / or at least partially from an insulating material. The bipolar plates may therefore, in particular, form part of a stack or "bag" of a fuel cell. The bipolar plates extend in particular in the width direction and in the longitudinal direction. The longitudinal direction is in particular the direction in which the bipolar plates have their largest main dimension. Meanwhile, the width direction may in particular be the direction in which the width of the bipolar plates is measured. The height direction may be perpendicular to the length direction and / or the width direction. In particular, the height direction may be the direction in which the material thickness of the bipolar plates is measured. It is particularly advantageous for the length direction and the width direction to be perpendicular to each other. Furthermore, the longitudinal, width, and height directions may preferably be perpendicular to one another. In other words, the longitudinal, width, and height directions may form a rectangular coordinate system. The bipolar plate includes a large number of openings. In particular, these openings may penetrate the bipolar plate completely, and the extension direction of the openings may be in particular the height direction. In other words, the openings may penetrate the bipolar plate in the height direction. This allows for the introduction of means, in particular connecting means, and / or fluids through the bipolar plate. In other words, the openings may thus function to allow fluids to flow from one side of the bipolar plate to the other side of the bipolar plate, and at the same time provide receiving space for fastening means, connecting means, tensioning means. Advantageously, the connecting means are thus tensioning means, i.e., means that provide or can provide tensioning of the bipolar plates relative to one another. In the context of the present invention, the connecting means may also be or be designed as fastening means. In particular, the flow openings of the openings are intended for fluid conduits. The opening itself is formed by one component, which is the flow opening, and by at least one further component, which is called the mounting opening.The mounting openings serve to accommodate the connection means, which may also be tensioning means that allow the bipolar plate and / or fuel cell stack to be tensioned. In other words, the openings may thus be formed by a combination of a mounting opening and at least one flow opening. It is advantageous for the bipolar plate to have a number of openings, each having at least one flow opening and one mounting opening. The openings are arranged or formed in such a way that they form an outer contour in the bipolar plate. The outer contour is the outer edge of the opening, particularly in the height direction, particularly on the face adjacent to the bipolar plate. This outer contour of the opening or openings is formed at least in part by the flow openings and at least in part by the mounting openings. In other words, the edge of the opening is formed at least in part by the mounting openings and at least in part by the flow openings. In particular, the mounting openings form a circular segment-shaped portion of the outer contour of the opening. In other words, at least a part of the outer opening is therefore formed by a circular portion that simultaneously defines the mounting opening. Alternatively, the openings may thus have a portion in the shape of a semicircular segment formed directly through the mounting opening. In this way, advantageous production costs as well as a particularly low notch effectiveness factor and a compact design of the mounting opening can be achieved, which are adapted to connecting means, in particular connecting means in the form of a screw. A screw in the sense of the present invention can in particular be a connecting means having an operating head and / or an operating part, and further in particular having an external and / or internal thread introduced into the shank part.

[0006] In a preferred embodiment, the bipolar plate has a flow region, which in particular subsequently serves to define a fluid volume, which fluid volume is or can be fluidly connected with at least two openings. The flow region is in particular a region or outer surface of the bipolar plate or a surface of the bipolar plate adjacent in height direction, which is or can be fluidly connected with an MEA later. The flow region can therefore form or include a surface on the bipolar plate. Advantageously, the bipolar plate has both a flow region formed by adjacent surfaces in the positive height direction and a flow region formed by adjacent surfaces in the negative height direction. In particular, the fluid region serves in particular to limit a fluid volume that will later be in communication with the MEA and / or to at least partially provide a volume in which the MEA will be located. The fluid region therefore abuts a fluid volume that is or can be fluidly connected with at least two openings in the bipolar plate. This is particularly crucial when a sealing element is or will be subsequently arranged on the bipolar plate, allowing fluid to flow from an opening to a fluid region and from a fluid region to another opening. In this way, a fluid inlet, in particular an opening in fluid communication with a fluid region or fluid volume, can be used to achieve fluid inflow and outflow into the fluid volume.

[0007] Advantageously, the mounting openings and the flow openings or openings of the openings pass through the bipolar plate, which makes it particularly easy to supply the flow fluid to the connecting means through the bipolar plate.

[0008] Advantageously, the flow opening is designed such that it extends from the mounting opening into the fluid field in a plane defined by the longitudinal and width directions, which makes it possible to achieve a particularly aerodynamically favorable design of the flow opening.

[0009] Advantageously, the circular segment-shaped portion of the mounting opening forms at least 51%, preferably at least 65%, and particularly preferably at least 75% of a circle. In other words, the circular segment-shaped portion may form at least 51%, preferably at least 65%, and particularly preferably at least 75% of a complete circle. By designing the mounting opening such that at least 51% is formed by the circular segment-shaped portion of the mounting opening, the position of the circular segment-shaped portion or the connecting means accommodated in the mounting opening can be secured. In other words, such a design can ensure, in particular, or at least provide in an emergency, secure locking of the connecting means in the mounting opening, so that slippage of the bipolar plate relative to the connecting means, in particular in the longitudinal and width directions, can be prevented or prevented by a secure locking method. To further improve this secure locking, the circular segment-shaped portion should form at least 65%, preferably at least 75%, of a complete circle. In this way, the secure locking between the bipolar plate and the connecting means can be further improved to achieve better accuracy of positional locking. This type of positive locking of the bipolar plates to the connecting means makes assembly particularly easy, in particular it allows the individual bipolar plates to be screwed onto the connecting means at a later stage, thus simplifying mounting.

[0010] Preferably, however, the circular segment-shaped portion of the mounting opening forms a maximum of 98%, preferably a maximum of 90%, and particularly preferably a maximum of 80% of the circle. The portion missing to form a complete circle belongs specifically to the flow opening. In other words, such a design can therefore ensure that there is enough space for the flow opening in the opening so that a sufficient flow area or flow options is provided.

[0011] Preferably, the bipolar plate has flow grooves, especially in one flow region of the bipolar plate, which end and / or start in particular at an opening. In other words, the bipolar plate may have grooves that can promote and / or achieve fluid flow, especially in the surface that defines the bipolar plate in the height direction. These grooves are especially called flow grooves. Advantageously, these flow grooves extend along the bipolar plate or are arranged on the bipolar plate so that they end and / or start at an opening, especially a flow opening. In other words, the grooves extend into the flow opening or openings. This allows a particularly favorable fluid connection of the flow grooves to be achieved. By providing flow grooves, in particular clogging and a uniform supply of fluid to the MEA can be achieved.

[0012] In preferred embodiments, the flow grooves are formed by straight and rectangular sections and / or the flow grooves are serpentine. By using only straight and / or rectangular or right-angled sections and / or serpentine designs, the flow grooves have a particularly large extension. This allows for a particularly effective and uniform fluid supply and / or drainage to and / or from the MEA into the flow grooves. Due to the serpentine design of the flow grooves, a particularly long flow length of the grooves can also be achieved, and therefore a particularly uniform fluid supply or drainage to and / or from the MEA is achieved.

[0013] Advantageously, the portion of the outer contour of the opening formed by the flow opening is further away from the center of gravity of the opening or the center of the circular segment-shaped portion than the portion of the outer contour of the opening formed by the mounting opening. In other words, the flow opening may extend away from the otherwise circular mounting opening, like an extension. Alternatively or even more preferably, the mounting opening forms all of the circular segment-shaped portion of the opening and / or is formed only by circular segment-shaped portions, in particular all having the same center point. These types of designs of the opening, some of the openings, a majority of the openings and / or all of the openings may create particularly good fluid path options. The center of the circular segment-shaped portion is in particular the point from which the radius of the circular segment-shaped portion is determined or the point that is the same distance from all points of the circular segment-shaped portion.

[0014] Preferably, the bipolar plate has a width-to-length ratio of 1 to 3 or less, and the bipolar plate has an opening, in particular a plurality of openings, in its central region in the longitudinal direction. In other words, the dimension of the bipolar plate in the width direction may have a ratio of 1 to 3 or less to the dimension of the bipolar plate in the length direction, in particular. If such a ratio exists, the opening, in particular a plurality of openings, may be provided in the central region in the longitudinal direction. The central region in the longitudinal direction is in particular a region of the bipolar plate in the longitudinal direction extending from the ideal center point in the longitudinal direction by + / - 25%, preferably + / - 15%, particularly preferably + / - 10%, and particularly preferably + / - 5% of the maximum length of the bipolar plate in the longitudinal direction. The center of the bipolar plate is in particular the volumetric center or center of gravity of the bipolar plate. The arrangement of the openings in the central region, in particular the arrangement of a plurality of openings as described above and below, allows for particularly good tensioning of the bipolar plate. In particular, bending moments due to tension can be avoided or reduced by the arrangement of the openings in the central region, all of which are advantageously designed as described above and below, in particular so that the openings thus comprise mounting openings and flow openings, and the connection means are or can be guided in particular through the flow openings.

[0015] Advantageously, the fuel cell comprises a sealing element, in particular a sealing ring. It is expedient for the sealing element to be arranged against the bipolar plate, so that the sealing element follows or can follow, at least in part, the circular segment-shaped portion of the outer contour of the opening. The fuel cell therefore comprises at least one sealing element, which can in particular be designed as a sealing ring. A sealing ring is understood as a self-contained sealing element. In other words, the sealing ring is therefore a sealing element without ends. In particular, the sealing element contacts the bipolar plate. This can in particular be achieved by direct contact between the sealing element and the bipolar plate. In other words, the sealing element can therefore always contact the bipolar plate along its extension. Advantageously, the sealing element follows, at least in part, the circular segment-shaped portion of the outer contour of the opening. The following should be understood to mean in particular that the projections of the sealing element and the projections of the outer contour in the plane spanned by the longitudinal and transverse directions overlap, that the course and the outer contour of the sealing element are the same at least in the following areas and / or that the sealing element abuts at least in part on the circular segment-shaped part of the outer contour. This following of the sealing element on the circular segment-shaped circle of the outer contour of the opening makes it possible to achieve a particularly short length of the sealing element and also a strong sealing effect.

[0016] In an advantageous embodiment, the sealing element follows at least 40%, preferably at least 60%, particularly preferably at least 80%, particularly preferably at least 90%, and very particularly preferably at least 97% of the circular segment-shaped portion of the outer contour of the opening. Alternatively, it is further preferred that the sealing element follows at least 40%, preferably at least 60%, particularly preferably at least 80%, particularly preferably at least 90%, and very particularly preferably at least 97% of the outer contour of the opening. By following at least 40% of the circular segment-shaped portion and / or the entire outer contour of the opening, particularly simple installation can be achieved. However, a particularly good sealing effect can be achieved if at least 60% or at least 80% of the circular segment-shaped portion of the outer contour and / or the entire outer contour of the opening is followed by the sealing element. On the other hand, a particularly good mechanical support capacity around the opening can be achieved if 90% of the outer contour or circular portion is followed by the sealing element. This capability is particularly noteworthy when the bipolar plate is reinforced by fastening or connecting means guided through the openings, since contact or tension forces can be safely dissipated directly via the sealing element. This should be understood to mean in particular that the circular segment-shaped portion of the outer contour of the opening or at least X percent of the portion following the outer contour of the opening, the projection of the circular segment-shaped portion of the outer contour or at least X percent of the entire outer contour in the plane spanned by the longitudinal and width directions, overlaps with the projection of the sealing element in this plane, and / or the sealing element abuts the circular segment-shaped portion of the outer contour or at least X percent of the outer contour.

[0017] Advantageously, a sealing element projects into the or one opening and / or into at least two openings. In particular, only openings having a mounting opening and a flow opening and / or through which the connection means is guided and / or which are designed to receive the connection means are relevant. By projecting inward, it can be achieved in particular that a seal is arranged between the connection means and the edge of the opening, preventing a connection between the connection means and the opening. In other words, the sealing element can thus be used to create an electronic insulation between the connection means and the bipolar plate.

[0018] Advantageously, the sealing element is made of an especially insulating material.

[0019] Advantageously, the fuel cell has a plurality of sealing elements, which at least partially follow the course of the outer contour of at least one opening and / or each opening is surrounded by the outer contour of the sealing element. This is particularly relevant for those openings that have mounting openings and flow openings and / or are designed to accommodate connection means. By forming the openings and / or at least one of the openings to be surrounded by the outer contour of the sealing element, it is achieved that the opening can be used to guide fluid into and / or out of a fluid volume. Surrounding an opening by the outer contour of the sealing element means that, in particular, in a projection in a plane formed by the longitudinal direction and the width direction surrounding the sealing element and the opening, the outer contour of the projection of the sealing element or the outer edge of this contour surrounds and / or includes the outer contour of the opening.

[0020] Preferably, the sealing elements are fixed to the bipolar plates in a particularly material-bonded and / or irreversible manner and / or the sealing elements are formed by a screen printing process. The advantage of using a screen printing process is the particularly cost-effective production of the sealing elements. By fixing the sealing elements to the bipolar plates, particularly simple installation of the fuel cell can be achieved. To achieve this fixing, the sealing elements are bonded to the material, in particular, by gluing and / or by a screen printing process. Advantageously, the sealing elements are irreversibly fixed to the bipolar plates so that the connection between the sealing elements and the bipolar plates can only be achieved by breaking the connection. This allows a particularly high sealing effect to be achieved.

[0021] Advantageously, the sealing elements are arranged on the bipolar plate so that they form a closed contour on the bipolar plate, and at least two flow openings, in particular different openings, and / or flow areas of the bipolar plate are advantageously arranged within the closed contour. By providing a closed contour of the sealing elements on the bipolar plate, a particularly strong sealing effect can be achieved. By arranging at least two flow openings within a closed contour, particularly good supply and removal of fluid into the sealed area can be achieved. In particular, the flow area of the bipolar plate and / or at least the contours of the outlets or flow openings (in particular at different openings) are also arranged within this sealed area or within the closed contour. In this way, particularly uniform or targeted supply and removal of fluid into the flow area of the bipolar plate can be achieved.

[0022] In a preferred embodiment, the fuel cell comprises a connecting means, which is guided through the opening, in particular the mounting opening of the opening, and which is in contact with the sealing element in particular. The contact between the sealing element and the connecting means can provide insulation between the connecting means and the bipolar plate. By passing the connecting means through the opening, in particular the mounting opening of the opening, a simple and space-saving clamping and mounting option can be achieved, in particular for the bipolar plate.

[0023] Advantageously, the connecting means have an actuation region, in particular a head, and a mounting region, the mounting region forming a thread. Advantageously, the mounting region is formed in and / or around the axial region of the connecting means. The connecting means extend in particular vertically. In other words, the main direction of extension of the connecting means is therefore advantageously formed parallel to the height direction. Particularly preferably, the connecting means are guided through respective openings in the bipolar plate, which have mounting openings and flow openings. This allows a particularly uniform tensioning of the bipolar plate to be achieved.

[0024] In a preferred embodiment, the connecting means has a flow channel extending in one height direction or along the height direction, the fluid channel being fluidly connected to a flow opening that co-forms with the opening through which the connecting means is guided. The flow channel can be a central recess, or the central recess can be a flow channel. For example, the connecting means can be a banjo, whereby the flow channel can be formed in the banjo. Alternatively, and preferably, the flow channel can also be formed externally in the connecting means, for example by an external groove. The fluid channel extends particularly in the height direction. In other words, the flow channel can thus provide a fluid transport capacity in the height direction. This flow channel of the connecting means is particularly fluidly connected with the flow opening, and fluid can flow from the flow channel to the flow opening. This can provide a particularly effective flow option. The flow channel can be particularly realized by a central recess of the connecting means.

[0025] Alternatively or in a further preferred embodiment, the fuel cell comprises a plurality of connection means, each of which is guided through an opening, which in particular comprises a mounting opening and / or a flow opening, in this way a particularly uniform stress distribution can be achieved and ultimately a particularly high density effect can be achieved, while at the same time valuable installation space can be saved.

[0026] Advantageously, the fuel cell includes an end plate, which extends in a longitudinal direction or longitudinal directions and a width direction or width direction, and which has two tension zones, particularly in the longitudinal direction, spaced apart from each other, and in particular the bending stiffness of the end plate between the tension zones is variable, advantageously decreasing in the direction toward the tension zones. In particular, the end plate extends in a longitudinal direction and a width direction, and the longitudinal direction of the end plate can correspond to the longitudinal direction described above and below and / or the width direction can correspond to the width direction described above and below. The longitudinal direction of the end plate is particularly the direction along which the end plate has its largest main dimension and / or the direction along which the length of the end plate is determined. Meanwhile, the width direction is particularly the direction along which the width of the end plate is determined and / or the direction along which the end plate has its second largest main dimension. The longitudinal direction and the width direction can be particularly perpendicular to the height direction, and in particular this height direction is parallel to and / or coincides with the height direction already described above and below. The end plate serves, in particular in a vertical direction, to be arranged in the fuel cell arrangement and to form the tip of the fuel cell. To achieve the attachment of the end plate, it has two tension zones, in particular spaced apart from each other. The tension zones are zones that function, in particular, to provide force transmission to the end plate. A zone of variable bending stiffness is advantageously provided between the two attachment zones. In particular, this zone of variable bending stiffness extends so that it includes and / or forms a central zone in the longitudinal direction of the end plate. The central zone of the end plate is similarly determined as the central zone of the bipolar plate. Advantageously, the bending stiffness of the zone located between the tension zones is designed so that it decreases in the direction of the tension zones. Thus, the bending stiffness is greatest in the zone furthest in the longitudinal direction, particularly towards the tension zones. Essentially, the end plate can also be called a head plate in the sense of the present invention.

[0027] In an advantageous embodiment, the end plates have curved reinforcing ribs, which extend in particular parallel to the longitudinal direction. Advantageously, these curved reinforcing ribs have a variable height in the longitudinal direction. In particular, the curved reinforcing ribs are designed such that they have their largest major dimension parallel to the longitudinal direction in order to provide good bending stress absorption.

[0028] Advantageously, the end plates, in particular the tension areas of the end plates, have fastening openings. Particularly preferably, the connection means extend through these fastening openings, which may also extend in particular through openings in the or some of the bipolar plates.

[0029] Preferably, the connection means are also in particular screws or bolts.

[0030] Advantageously, the connecting means comprises an actuation region, in particular a head, an elastic region, and preferably a mounting region, the connecting means extending in the direction of travel, the radial direction being particularly perpendicular to the direction of travel, the elastic region may be between the actuation region and the mounting region in the direction of travel, the mounting region having a thread, in particular an internal thread, the elastic region and / or the mounting region being or may be hollow inside, and / or the elastic region having a lower elasticity due to its shape than the mounting region and / or the actuation region. The connecting means is used in particular to connect different components to one another, in particular in a force-fit manner. This force-fit manner is advantageously related to particularly lateral forces in the radial direction or parallel to this direction. In order to be able to establish or transmit lateral forces, in particular perpendicular to the direction of travel, between the connected components, the connecting means is therefore advantageously designed as a force-fitting connecting means. In particular, the connecting means comprises an actuation region. The actuation region is advantageously used to apply an attachment torque to the connector, in particular in a form-fit manner. For this purpose, the actuation area may have actuation surfaces in the form of, in particular, an external hexagon, an internal hexagon, an external or internal hexalobular, a multi-tooth, and / or a multi-round, in each case advantageously for internal and / or external actuation. Advantageously, the normal to the actuation surfaces points in the radial direction. These actuation surfaces may be part of the heads, which in turn may form the actuation area. In other words, the actuation area may be formed by or include the heads. Advantageously, the actuation area is formed so that it forms the tip of the connecting means in the direction of travel. The direction of travel is likewise, in particular, the direction in which the connecting means has its largest main dimension. For example, the direction of travel may therefore, or alternatively, preferably, be the direction in which the length of the connecting means is measured. In particular, the direction of travel is parallel to the height direction. The center of gravity of the connecting means, the elastic area, and / or the mounting area may be in the longitudinal direction. In particular, one of the radial directions or the radial direction extends perpendicular to the direction of travel. Advantageously, the direction of travel, the radial direction and the circumferential direction form a cylindrical coordinate system with one another. In particular, the direction of travel is parallel to and / or coincides with the height direction. The radial direction may be parallel to the width direction and / or the direction of travel. In addition to the actuation region, the connection means also have elastic regions and / or mounting regions.The mounting area of the connecting means has a thread for forming a connection with another thread, in particular a nut thread. This thread can advantageously be designed as an internal thread, in order to achieve a particularly space-saving design. Alternatively or additionally, preferably, the thread of the mounting area can also be an external thread. This particularly facilitates manufacturing. The thread itself can likewise be a metric or imperial thread. Preferably, the mounting area is limited in the travel direction by the tip of the thread in the travel direction. Advantageously, the mounting area forms the tip of the connecting means in the travel direction. The mounting area having and / or formed by the thread can define the connecting means in the travel direction. To reduce the risk of injury during mounting, the mounting area can be limited by and / or have a cylindrical surface facing outward in the radial direction. An elastic area is located between the operating area and the mounting area when viewed in the travel direction. Advantageously, the length of the elastic area in the travel direction is greater than the length of the operating area and / or the mounting area in the travel direction. In particular, the lengths of all areas are measured in the travel direction. Advantageously, the length of the elastic region in the longitudinal direction is greater than the sum of the lengths of the actuation region and the mounting region. Advantageously, at least 30%, preferably at least 60%, and particularly preferably at least 70% of the length of the connection means in the direction of travel is formed by the elastic region. The elastic region and / or the mounting region are particularly hollow in the interior in order to form or provide easy mounting and / or gas channels and / or reduced elasticity. Due to its geometry, the elastic region is designed to have lower elasticity than the mounting region, and the elastic region has a deforming structure and / or a stiffness-reducing structure, particularly in the form of a deforming structure. In other words, the geometry of the elastic region in particular is such that this results in a lower elasticity in the mounting region than in the mounting region and / or actuation region. The elasticity itself is particularly the gradient of the spring stiffness or force path diagram. The elasticity is measured in the direction of travel. In particular, this force path diagram or spring stiffness is not non-dimensionalized by geometric parameters. In other words, the elasticity or spring stiffness is therefore not determined by the slope of the stress-strain diagram, but by the actual applied force in the elastic region compared to the resulting displacement or deformation.The force path diagram therefore records the force that must be applied to separate the mounting area from the actuation area in the direction of travel, and at the same time the resulting displacement of the actuation area towards the mounting area in the direction of travel. Advantageously, the elastic area and the mounting area and / or the elastic area and the actuation area are made of the same material and / or in one piece. This allows particularly good mechanical durability to be achieved. Due to the lower elasticity of the elastic area, due to the geometry of the elastic area and / or due to the reduced stiffness structure, the expansion and / or statically occurring expansion loads of the connected components can be reduced. In particular, this can reduce the load on the connecting means and / or on the clamped or reinforced components, so that the operational safety and durability of the connecting means can be improved. A further advantage of such a design is that the dynamic loads on the connecting means are also reduced.

[0031] Advantageously, the elastic region has one or more deformation structures that undergo bending and / or torsion when the actuation region is displaced in the direction of travel relative to the mounting region. The deformation structures are, in particular, spiral or beam segments, and can be achieved, for example, by introducing recesses and / or openings or other stiffness-reducing structures into the elastic region, in particular in the radial direction. These deformation structures are therefore, in particular, not recesses, but material regions that are mechanically stressed by the change in length of the elastic region in the direction of travel, in particular by the displacement of the mounting region in the direction of travel relative to the actuation region. This mechanical stress on the deformation structures is, in particular, or includes, bending and / or torsional loads. This type of load is, in particular, the dominant type of load, and therefore, in particular, a type of load that generates at least 30%, preferably at least 50%, and particularly preferably at least 70% of the comparative stress, in particular when applying the shape change hypothesis (von Mises) and / or the principal normal stress hypothesis (Rankine). In particular, this can increase the achievable reversible deformation degree of the deformation structures, ultimately reducing the elasticity of the elastic region. In other words, by using a deformation structure that undergoes bending and / or twisting when the actuation area is displaced in the forward direction relative to the mounting area, the spring stiffness of the elastic area, which may be synonymous with its elasticity, can therefore be reduced, thus achieving a particularly advantageous design of the elastic area.

[0032] Advantageously, the elastic region is designed to have a degressive spring characteristic. In other words, the elasticity or spring stiffness of the elastic region may be such that, with respect to the displacement of the working region in the direction of travel relative to the mounting region, the elasticity is reduced or decreased as the distance of the working region in the direction of travel relative to the mounting region increases. In particular, this allows the dynamic load to be further reduced with increasing expansion of the connected components, or allows the resulting (static) load to increase less sharply. Advantageously, the spring characteristic is degressive in the elastic region. In other words, the degressive spring characteristic is achieved "before" irreversible deformation occurs. In particular, this may minimize or reduce permanent stress relaxation and / or mechanical overstress of the connected components and / or connection means.

[0033] Advantageously, the elastic region has one or more stiffness-reducing structures, in particular recesses and / or openings, which form or define the deformation structure. In other words, recesses and / or other stiffness-reducing structures adjacent to the deformation structure may be formed in the elastic region, in particular in the radial direction. In particular, these recesses may be formed in such a way that they allow fluid to pass from the surroundings through the recesses or openings into the internal hollow region or the completely hollow internal elastic region. In other words, the opening or openings may be designed so that they extend from the outside into the hollow interior of the elastic region.

[0034] The internal hollow region of the connecting means may in particular be formed by a central recess which extends in the direction of travel from the assembly region to the elastic region or even to the actuation region. By providing such a central recess, fluid flow may therefore also be achieved between the individual regions of the connecting means in the direction of travel.

[0035] Advantageously, the stiffness-reducing structure, in particular in the form of a recess or recesses, combines the outer wall of the elastic region with the inner wall of the elastic region. The outer wall of the elastic region adjoins it on the outside, in particular in the positive radial direction, and the inner wall adjoins the elastic region on the inside, in particular in the direction of travel. In particular, this inner wall may adjoin and / or partially form a central recess. Thus, fluid flow can be achieved in a particularly effective and direct manner from the periphery to the internal hollow region of the elastic region, as already explained.

[0036] Advantageously, at least one stiffness-reducing structure, in particular in the form of a recess, is designed so that its projection in the direction of travel is self-enveloping. In other words, at least one recess can be designed in such a way that, when this recess is projected onto a plane perpendicular to the direction of travel, the projection is self-enveloped and thus can form a ring, in particular around the direction of travel. This allows a particularly high degree of elasticity reduction to be achieved, resulting in particularly advantageous elastic regions. Advantageously, however, the ends of the recess that form the self-enveloping or self-contained projection are located at different heights in the direction of travel. In other words, the recess, which may in particular be an opening, is only self-enveloped in the projection, not when viewed in view of its extension in the direction of travel. In particular, this can prevent a sudden weakening of the connection means.

[0037] Advantageously, the elastic region has one or more spiral recesses and / or stiffness-reducing structures, in particular openings, so that the elastic region has one or more spiral and / or multiple deformation structures. By providing stiffness-reducing structures, which may in particular be spiral recesses and / or openings, a particularly effective way of torsionally loading the deformation structure can be achieved. By providing a torsionally loaded deformation structure, a particularly high degree of reversible deformation capacity can be provided. By providing a spiral deformation structure, particularly good torsional loading can be achieved. As already mentioned, several spirals can also be provided, so that multiple spiral deformation structures can exist. In other words, multiple spiral deformation structures can be designed similarly to multiple screws.

[0038] Advantageously, the deformation structure, in particular the spiral, has a material thickness in the direction of travel and a radial thickness in the radial direction, which may also be referred to as the radial thickness, the ratio of the material thickness to the radial thickness being in the range of 0.8 to 1.2, preferably in the range of 0.9 to 1.1, and particularly preferably in the range of 0.97 to 1.03. The material thickness is thus the average and / or maximum or minimum material thickness of the deformation structure measured in the direction of travel. The radial thickness of the deformation structure is particularly the material thickness or material thickness in the radial direction. Advantageously, the ratio of the material thickness to the radial thickness is in the range of 0.8 to 1.2. This makes manufacturing particularly easy. On the other hand, if the material thickness is in the range of 0.9 to 1.1, a particularly advantageous stress distribution can be achieved. On the other hand, if the ratio is in the range of 0.97 to 1.03, an approximately uniform stress distribution can be achieved at all ends.

[0039] Advantageously, at least one recess and / or stiffness-reducing structure, preferably several recesses and / or stiffness-reducing structures, are elongated. Preferably, the or at least one, preferably at least a number, and particularly preferably all stiffness-reducing structures or recesses having an elongated shape are formed as openings. A recess / stiffness-reducing structure is considered to have an elongated shape, especially if it has a larger dimension in its main extension direction than perpendicular thereto. In other words, if the length of the opening in the circumferential direction is greater than the length of the opening in the direction of travel, an elongated recess or elongated hole may therefore be present. In particular, the length of the opening and / or recess in the radial direction is not important. In other words, only the contour that the recess and / or opening leaves on the outer wall of the elastic region may therefore be decisive for the elongated hole shape. Advantageously, the extent of the elongated hole-shaped opening or the recess of the elongated hole-shaped opening is greater, especially in the circumferential direction, than in the direction of travel. Advantageously, the extension in the circumferential direction, due to the slot-shaped definition, is at least 10%, preferably at least 20%, and particularly preferably at least 30% greater than in the direction of travel. Advantageously, the tip region of the slot-shaped opening or slot-shaped recess is formed by rounding. This can reduce the resulting material stress rise or stress rise factor.

[0040] Preferably, the elongated recesses or protrusions of the stiffness-reducing structures form closed circles in the direction of travel, in particular in the direction of travel. In other words, the protrusions of the elongated recesses, which may in particular be openings, can be formed such that when viewed in the direction of travel, they overlap to form complete circles or self-contained rings, in particular with their centres of gravity in the direction of travel and / or surrounding the direction of travel. This allows a particularly advantageous reduction in the elasticity of the elastic region to be achieved.

[0041] Preferably, at least one stiffness-reducing structure and / or slot-shaped recess has a variable width in the direction of travel and / or in the longitudinal direction. The width is in particular the distance between opposing walls in the direction of travel and / or in the longitudinal direction. In particular, the slot or slot-shaped recess is oriented so that it extends perpendicular to the direction of travel. In other words, the main direction of extension is therefore oriented perpendicular to the direction of travel and / or the longitudinal direction when projected radially. In particular, a defined stress distribution can be achieved by the variable width in the direction of travel and / or in the longitudinal direction. Advantageously, the width of the slot-shaped opening or recess decreases toward the center of the opening or recess. In other words, the width of the recess can first decrease from one end of the opening or recess to the other end of the recess, and then increase again after passing through the center between the ends of the recess. In this way, a particularly advantageous prediction of the generated mechanical stress can be achieved. In other words, a particularly stress-adapted course can be achieved.

[0042] Advantageously, the deformation structure, in particular the deformation structure arranged between two elongated openings, has a material thickness, in particular a maximum material thickness in the direction of travel, and a material thickness, in particular a maximum material thickness in the radial direction, which, as already explained, may be referred to as the radial thickness, with the ratio of the material thickness to the radial thickness being in the range of 0.7 to 1.3, preferably in the range of 0.85 to 1.15, and particularly preferably in the range of 0.9 to 1.1. The material thickness, as already explained, is the average and / or maximum or minimum material thickness of the deformation structure, in particular measured in the direction of travel. The radial thickness of the deformation structure, also as already explained, is in particular the material thickness or material thickness in the radial direction. Advantageously, the ratio of the material thickness to the radial thickness is in the range of 0.7 to 1.3. This allows for particularly cost-effective production, in particular when the deformation structure is at least partially limited in the direction of travel by the elongated opening. On the other hand, if the material thickness is in the range of 0.85 to 1.15, particularly low local stress concentrations can be achieved, especially when the deformation structure is at least partially limited in the direction of travel by elongated holes, while on the other hand, if the ratio is in the range of 0.9 to 1.1, particularly good elasticity gains can be achieved.

[0043] Advantageously, the ratio of the average or maximum height of the opening, particularly the elongated opening, in the direction of travel to the diameter of the elastic region is in the range of 0.045 to 0.125, preferably in the range of 0.055 to 0.0834, and particularly preferably in the range of 0.06 to 0.75. The average or maximum height of the opening in the direction of travel is the width of the opening in the direction of travel, particularly the width between two opposing walls in the direction of travel. Meanwhile, the average height is the average height of the opening in the direction of travel between one end and the other end in the direction of travel. Meanwhile, the diameter of the elastic region is the diameter of the smallest possible circle lying in a plane perpendicular to the direction of travel and capable of exactly enclosing the elastic region. When the ratio is in the range of 0.045 to 0.125, this can achieve particularly effective reduction in elasticity. Meanwhile, when the ratio is in the range of 0.055 to 0.0834, this can result in simple manufacturing.

[0044] Advantageously, the connecting means is designed as one piece. One-piece connecting means means, in particular, that the materials of the connecting means are joined together in a single original primary forming process. In other words, the connecting means can be further processed after this original forming process, in particular by separation or division processes such as laser cutting and / or screw cutting and / or milling or turning, but no additional elements are added to the connector, for example, by welding. Advantageously, however, only the actuation region, the elastic region, and the mounting region are formed integrally with one another. Alternatively or additionally, and preferably, the connecting means can also result from joining further components to one another by material bonding, in particular by material bonding of the actuation region to the elastic region and the mounting region. In addition, further elements can also be attached to the connecting means with this material-locking connection, so that, ultimately, the result is a connecting means having the actuation region, the elastic region, and the mounting region joined together by a material-locking connection, but the further elements can be attached to the connecting means by force-fitting and / or form-locking and / or material-locking methods. Material-locking connections are advantageous, in particular in terms of production costs. On the other hand, the integral design of the actuation area and the mounting area with the connecting means and / or the elastic area results in a particularly mechanically advantageous design.

[0045] Advantageously, the working area is hollow, in particular hollow inside. In particular, this allows fluid to flow through the elastic area and / or through the mounting area into the hollow area of the working area. As a result, the connecting means described here can be used particularly advantageously in fuel cells. The term hollow means in particular that the entire working area can be hollow in the direction of travel.

[0046] Advantageously, the working area has a gas connection, which makes it particularly easy to achieve a gas flow from and / or to the working area, in particular the gas connection may have or form an airtight thread and / or hose connection.

[0047] Advantageously, a central recess is provided, which extends in the direction of travel from the actuation region beyond the elastic region and can reach the mounting region. Advantageously, this central recess extends from an end of the mounting region to one end of the actuation region. In other words, the central recess can extend through the connecting means in the direction of travel, in particular to enable fluid flow through the connecting means. Advantageously, this central recess has a constant diameter in the actuation region, the elastic region and / or the mounting region. This makes it possible to achieve a particularly simple and cost-effective production, which also has advantageous mechanical properties.

[0048] Advantageously, the working area has a working surface, the working surface having a normal in particular in the radial direction. As a result, torque, in particular form-fitting torque, in particular about the direction of travel, can be used in a simple way to attach the connecting means to the connecting means. By providing the working surface normal pointing in the radial direction, a particularly cost-effective production can be achieved and it can also be easily operated.

[0049] Advantageously, the recess(es) and / or opening(s), in particular the recess(es) and / or opening(s) forming a spiral and / or formed like a slot, are laser cut, which results in a particularly cost-effective and precise manufacturing, and local (undesirable) stress concentrations can be avoided and / or reduced.

[0050] Further aspects of the invention may relate to the use of a connection means in / for a fuel cell as described above and / or below.

[0051] Further aspects of the invention may relate to the use of the bipolar plates and / or bipolar plate systems described above and / or below in / for the fuel cells described above and / or below.

[0052] A further aspect of the invention may relate to the use of an end plate as described above and / or below in / for a fuel cell as described above and / or below.

[0053] Advantageously, the fuel cell comprises at least one bipolar plate, preferably a plurality of bipolar plates, in particular as described above and / or below. Alternatively or more preferably, the fuel cell may also comprise one or a plurality of connecting means and / or sealing elements, in particular as described above and / or below. Furthermore, optionally or more preferably, the fuel cell may also comprise at least one end plate or two end plates, in particular as described above and / or below.

[0054] In a preferred embodiment of the fuel cell, a cavity is formed between and / or in two bipolar plates, the cavity being partially bordered by a flow field of one or both bipolar plates, and a fluid can enter or exit the cavity through one of the openings, in particular a flow opening of a bipolar plate, and / or a fluid can enter or exit the cavity through one of the openings, in particular a flow opening of a bipolar plate. In other words, a flow field of a bipolar plate can thus be fluidly connected with a flow opening of one opening and a flow opening of another opening. This can create a particularly effective and simple way of bringing a fluid into contact with the flow field through the flow opening.

[0055] In a preferred further development, an MEA is arranged in the cavity. The MEA is a membrane electrode assembly. This allows a particularly compact design of the fuel cell to be achieved.

[0056] A further aspect of the invention may relate to a method for manufacturing a connection means, in particular as described above and below, in particular the method comprising the following steps: ●Especially preparing blanks Forming the working area, in particular the head, advantageously by molding - Forming the mounting area, especially the hollow area, by forming - forming elastic regions, advantageously in the form of recesses and / or openings, in the travel direction between the actuation area and the mounting area, in particular by introducing stiffness-reducing structures;

[0057] The insertion of the stiffness-reducing structure may be carried out in particular by laser, for example by laser cutting. The connection means provided by the manufacturing method may have in particular the features, configurations, embodiments and advantages described above and below. In particular, the shaping of the actuation area and / or the shaping of the elastic area and / or the shaping of the mounting area is carried out by a forming process in order to achieve a particularly mechanically resilient and still cost-effective design for the connection means. In particular, the connection means may be screws and / or bolts. [Brief explanation of the drawings]

[0058] Further advantages and features of the present invention are set forth in the following description with reference to the figures. Individual features of the illustrated embodiments can also be used in other embodiments, unless expressly excluded. It shows the following: [Figure 1] Figure 1: Bipolar plate; [Figure 2] Figure 2: Fuel cell and / or bipolar plates; [Figure 3] Figure 3: Selective design diagram of bipolar plate; [Figure 4] FIG. 4: Fuel cell with bipolar plates and connection means; [Figure 5] Figure 5: Fuel cell with end plates and multiple bipolar plates; [Figure 6] Figure 6: Isometric view of end plate; [Figure 7] FIG. 7: Side view of a connecting means having a stiffness-reducing structure in the form of an elongated hole; [Figure 8] FIG. 8: A connecting means having a stiffness-reducing structure such as a recess, the width of which decreases towards the center; [Figure 9] Figure 9: Partial view of the connection means in the fuel cell; [Figure 10] Figure 10: Multiple connection means in a fuel cell; [Figure 11] FIG. 11: Side and cross-sectional views of the connection means; and [Figure 12] FIG. 12: Connection means with a modified structure that is a spiral;

[0059] 1 shows an isometric view of a bipolar plate 210. The bipolar plate 210 has a plurality of openings 240 extending in a height direction H. Each opening 240 includes a mounting opening 242 and a flow opening 244. Each mounting opening 242 has a circular segment-shaped portion and / or forms a circular segment-shaped portion of the outer contour of the opening 240. The mounting openings 242 are configured to receive connecting means, the bipolar plate has a width-to-length ratio of 1 to 3 or less, and the plurality of openings 240 are arranged on the bipolar plate 210 in a central region in the longitudinal direction L. As a result, a particularly uniform distribution of tension can be formed on the bipolar plate 210.

[0060] FIG. 2 shows an isometric view of bipolar plates 210 arranged one above the other in the height direction H. A sealing element 310 is arranged between each bipolar plate 210. In other words, FIG. 2 also shows a bipolar plate system 300 that may include bipolar plates 210 and sealing elements 310. The bipolar plate system is therefore part of the present invention and may be used in bipolar plates according to the present invention. This situation is irrelevant to the embodiment. As seen from the highest bipolar plate 210 in the height direction H, multiple sealing elements 310 are fixed to it. These sealing elements 310 each surround an opening 240. Each opening 240 includes at least one mounting opening 242 and one flow opening 244. The sealing elements 310 follow at least 60% of the circular segment-shaped portion of the outer contour of each opening 240. The circular segment-shaped portion of the mounting opening 242 forms at least 65% of the circle of each opening 240. The flow openings 244 are formed such that they face towards the flow field 252. The flow field 252 is also surrounded by sealing elements 310. Each sealing element 310 protrudes at least partially into the opening 240 or into both openings 240, i.e. at least partially into the mounting opening 242. This may create a particularly good insulation option for the connection means 9, which may be accommodated in the mounting opening 244, as shown, for example, in FIG.

[0061] 3 shows a diagram of a bipolar plate 210 having six openings 240 extending in a height direction H. A width direction B and a length direction L are perpendicular to the height direction H. Flow grooves 250 leading through a flow region 252 extend from the opening 240 located at the lower left to the opening 240 located at the upper right. The flow grooves 250 are arranged in a serpentine pattern.

[0062] The flow region 252 is surrounded by a sealing element 310 , which also surrounds the two openings 240 .

[0063] 4 shows a fuel cell 1 or a part of a fuel cell 1, in particular a bipolar plate system 300 comprising a plurality of sealing elements 310 and a plurality of bipolar plates 210 and connection means 9. The connection means 9, which may also be called connectors, extends in a height direction H. As can be seen from FIG. 4, the plurality of sealing elements 310 contact the bipolar plates 210 and the connection means 9. The connection means 9 is designed such that it has flow channels which extend in the height direction H, the flow channels being fluidly connected with the flow openings 244 of each opening 240. This allows a particularly good and advantageous flow supply and / or discharge through the connection means 9.

[0064] 5 shows a fuel cell 1, which comprises a plurality of connection means 9 and a plurality of bipolar plates 210 and / or bipolar plate systems 300. The fuel cell 1 is at least partially surrounded in the height direction H by end plates 500.

[0065] 6 shows an end plate 500. The end plate 500 extends in a longitudinal direction L and a width direction B, and has tension zones 502 spaced apart from one another in the longitudinal direction L, with fastener openings 510 disposed in the tension zones 502. The tension zones 502 are arranged such that they each have at least three fastener openings 510. Between the attachment zones 502, particularly as viewed in the longitudinal direction L, the end plate 500 has a variable bending stiffness that decreases in the direction toward the tension zones 502. This variable bending stiffness can be achieved by stiffening ribs 520 extending parallel to the longitudinal direction L.

[0066] 7 shows a connecting means 9 having an actuation area 10 in the form of a head. The actuation area 10 has a connecting thread for a gas connector. In addition, the connecting means 9 also has a mounting area 50, the fastening area 10 and the mounting area 50 forming the distal opposite end areas of the fastening means / connecting means 9 in the direction of travel V. An elastic area 30 is located between the fastening area 10 and the mounting area 50. Due to its shape, the elastic area 30 has a lower elasticity than the mounting area 50 and than the actuation area 10, and the elastic area 30 has a reduced spring characteristic. These stiffness characteristics of the elastic area 30 are achieved by a stiffness-reducing structure in the form of an elongated hole formed as an opening.

[0067] Figure 8 shows a similar fastening / coupling means 9 compared to Figure 7. However, the actuation area 10 has an external hexagon with an actuation surface 12. In the mounting area 50, which is hollow on the inside, there is an internal thread for mounting. The radial direction R points radially from the direction of travel V. Deformation structures 32 present in the elastic areas 30 are such that they have a variable width in the direction of travel V, the width decreasing towards the centre of the recess.

[0068] 9 shows a detailed view of the connection means 9 mounted on the fuel cell. Both the actuation area 10 with the actuation surface 12 therein and the elastic area 30 are provided with a central recess 60, resulting in an internal hollow area in both the actuation area 10 and the elastic area 30. The stiffness reduction structure is designed in the shape of an elongated hole. The stiffness reduction structure 34 forms the deformation structure 32, which has a radial thickness RS in the radial direction R.

[0069] 10 shows a fuel cell with multiple connection means 9. The connection means 9 completely penetrate the fuel cell 9 in the direction of travel V and in the height direction H. Essentially, the connection means 9 or the direction of travel V should be parallel to the longitudinal direction L or the height direction H.

[0070] 11 shows a side view of the lower region and a cross section through the connecting means 9 in the upper region. The connecting means 9 extends in the direction of travel V. In the elastic region 32, leaf spring-like deformation structures 32 are formed in series. Due to this geometric design, the elastic region 30 has a cumulative spring characteristic. A radial thickness RS can be seen in the elastic region. Both the mounting region 50 and the elastic region 30 are hollow on the inside and therefore each has a central recess 60. To achieve mounting of the connecting means 9, the mounting region 50 has an internal thread.

[0071] 12 shows the connecting means 9. The connecting means 9 has a deformation structure 32 which is a spiral. In other words, the elastic region 30 has a helical depression which forms the deformation structure 32. The deformation structure 32 has a material thickness MS in the direction of travel V. Alternatively, instead of a helical depression, several helical depressions can also be provided, resulting in a multi-threaded deformation structure or a deformation structure in the form of a spiral. The mounting region 50 also has a metric internal thread.

[0072] List of reference symbols: 1 - fuel cell 9 - Connection means 10 - Working area, especially the head 12 - Working surface 30 - Elastic area 32 - Deformed Structure 34 - Reduced stiffness structures, depressions, especially openings 50 - Wearing area 60 - Central recess 210 - Bipolar Plate 240 - aperture 242 - Mounting opening 244 - Flow opening 250 - Flow groove 252 - Flow Region 300-Bipolar Plate System 310 - Sealing element 500 - End Plate 502 - Tension area 510 - Fastening opening 520 - Rigid rib B - Width direction L - Longitudinal H - Height V - Direction of travel MS - Material Thickness R - radial RS - Radial Thickness U - Circumferential direction

Claims

1. A fuel cell (1) comprising a bipolar plate (201), in particular a plurality of bipolar plates (210), and / or a connection means (9), in particular a plurality of connection means (9), The bipolar plate (210) extends in a longitudinal direction (L) and a width direction (B), The longitudinal direction (L) and the width direction (B) are particularly perpendicular to each other, The bipolar plate (210) has a plurality of openings (240); the opening (240) has an outer contour; the outer contour of the opening (240) is in particular formed in each case by a mounting opening (242) and at least one flow opening (244), said mounting opening (242) advantageously forms a circular segment-shaped portion of said outer contour of said opening (240); and the mounting opening (242) or the opening (240) is designed to receive the connecting means (9) or the connecting means (9), Fuel cell (1).

2. the circular segment-shaped portion of the mounting opening (242) forms at least 51%, preferably at least 65% and particularly preferably at least 75% of a circle; A fuel cell (1) according to claim 1.

3. the circular segment-shaped portion of the mounting opening (242) forms a maximum of 98%, preferably a maximum of 90%, and particularly preferably a maximum of 80% of a circle; A fuel cell (1) according to claim 1 or 2.

4. A fuel cell (1) comprising a sealing element (310), in particular a sealing ring, The sealing element (310) contacts the bipolar plate (210), the sealing element (310) at least partially follows the circular segment-shaped portion of the outer contour of the opening (240); Fuel cell (1).

5. The sealing element (310) protrudes into the opening (240) or into at least two of the openings (240). A fuel cell (1) according to claim 4.

6. the sealing element (310) is fixed to the bipolar plate (210), in particular in a materially bonded and / or irreversibly manner, and / or The sealing element (310) is manufactured by a screen printing process or a mold-in-place process. A fuel cell (1) according to claim 4 or 5.

7. the sealing element (310) is arranged on the bipolar plate (210) in such a way that the sealing element (310) forms a closed contour on the bipolar plate (210); at least two flow openings (244), in particular different openings (240), and / or flow areas (252) of said bipolar plate (210), are arranged within said closed contour, A fuel cell (1) according to any one of claims 4 to 6.

8. said connecting means (9) comprising an actuation region (10), in particular a head, an elastic region (30) and a mounting region (50); The connecting means (9) extend in the direction of travel (V), the radial direction (R) is particularly perpendicular to said direction of travel (V), the elastic region (30) is between the actuation region (10) and the mounting region (50) in the direction of travel (V); the mounting area (50) has a thread, in particular an internal thread, the elastic region (30) and / or the mounting region (50) are hollow, in particular internally, the elastic region (30) has stiffness-reducing structures (34), in particular in the form of recesses and / or openings; and / or the elastic region (30), due to its shape, has a lower elasticity than the mounting region (50) and / or the actuation region (10); and / or The elastic region (30) has a cumulative spring characteristic. A fuel cell (1) according to any one of claims 1 to 7.

9. the elastic region (30) has one or more deformation structures (32) that are subjected to bending and / or twisting when the actuation region (10) is displaced in the travel direction (V) relative to the mounting region (50); A fuel cell (1) according to any one of claims 1 to 8, in particular claim 8.

10. The elastic region (30) has a cumulative spring characteristic. A fuel cell (1) according to any one of claims 1 to 9, in particular claims 8 or 9.

11. At least one depression (34), preferably a plurality of depressions (34), is elongated; A fuel cell (1) according to any one of claims 1 to 10, in particular according to any one of claims 8 to 10.

12. a central recess (60) is present, which extends in the direction of travel (V) from the actuation region (10) through the elastic region (30) to the mounting region (50), in particular to the distal end of the mounting region (50); A fuel cell (1) according to any one of claims 1 to 11, in particular according to any one of claims 8 to 11.

13. the connecting means (9) is guided through the opening (240), in particular through the mounting opening (242) of the opening (240), the connecting means (9) contacts the sealing element (310) or one of the sealing elements (310), A fuel cell (1) according to any one of claims 1 to 12.

14. the connecting means (9) has flow channels extending along the height direction (H) and / or the central recess (60), the flow channels and / or the central recess (60) are in fluid communication with flow openings (244), the flow openings (244) being integrally formed with the openings (240) through which the connecting means (9) are guided; A fuel cell (1) according to any one of claims 1 to 13, in particular claim 13.

15. Use of a bipolar plate (210) and / or a bipolar plate system (300) in a fuel cell (1) according to any one of claims 1 to 14, and / or Use of a connecting means (9) in a fuel cell (1) according to any one of claims 1 to 14.

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