SPRING DEVICE

Abstract

The present invention relates to a spring device comprising a first suspension element, a second suspension element and a plurality of constant-force spring elements, wherein the first and the second suspension element are suspended so as to be movable relative to each other in a spring direction via the constant-force spring elements, and wherein at least some of the constant-force spring elements are arranged in a package in a translational direction which has at least a component in the spring direction in a translationally symmetrical manner to each other, and / or are arranged in a rotationally symmetrical manner to each other about an axis of rotation which is at least partially parallel to the spring direction when viewed in the spring direction.

Description

DESCRIPTIONTechnical area

[0001] The present invention relates to a spring device. background

[0002] The spring device in question comprises a first and a second suspension element, which are suspended so as to be movable relative to one another in a spring direction. For example, the travel is taken in the spring direction when determining the characteristic curve of the spring device for a force-travel diagram. In practice, when two parts are to be resiliently mounted relative to one another, one part is assigned to the first suspension element and the other part to the second suspension element. These can each provide a plate-shaped support for this purpose, for example, but this is not mandatory. Description of the invention

[0003] The present invention is based on the technical problem of providing an advantageous spring device.

[0004] This is achieved according to the invention with the spring device according to claim 1. This has several constant force spring elements, via which the first and second suspension elements are mounted so as to be movable relative to one another. At least some of the constant force spring elements i) arranged in a translational direction, which has at least a portion in the spring direction, translationally symmetrical to one another in a package, and / or ii) viewed in the spring direction, are arranged rotationally symmetrically to one another around an axis of rotation which is at least partially parallel to the spring direction.

[0005] This combination of features allows for scalability, for example, a package according to point i) can be supplemented with one or more constant-force spring elements if the spring force of the device is to be increased (and, conversely, the number can be reduced for a lower spring force). On the other hand, the symmetrical arrangement also allows for a compact design, allowing the constant-force spring elements to be accommodated in a space-saving manner. This allows, for example, a base area defined by the suspension elements to be used efficiently, i.e., to be filled relatively "densely" with the constant-force spring elements.

[0006] Constant-force spring elements each have a characteristic curve where, unlike an ideal spring, the force increases with displacement, i.e., deflection or deformation, not linearly, or at least with a smaller gradient compared to the beginning and / or end of the characteristic curve. Instead, the force remains essentially constant within the operating range, e.g., see [Fig. 1]. Fig. 7 for illustration. The spring device as a whole, which combines several constant-force spring elements, also has a working range in which the force is constant or, at most, slightly increases or decreases. This allows, for example, a pressing force applied by the spring device to be decoupled from any inhomogeneities or deviations outside the spring device, thus allowing an essentially constant force to be applied regardless of external fluctuations.

[0007] A particularly advantageous application area for this spring device can be in a fuel cell stack, which is also referred to as a stack. In this case, several fuel cells are placed next to one another in a stacking direction, wherein a cover element is provided following the fuel cells in the stacking direction, which holds the fuel cells together with a pressing force. For this purpose, it can be braced, for example, via tie rods or similar, to another cover element that is arranged at the opposite end. Independently of these details, the present spring device can be used for the force transmission between the cover element and the fuel cells, i.e. it can be arranged between the fuel cells and the cover element. This means that, if, for example, a larger cover element bends and / or due to geometric inhomogeneities (e.g.If a deviation occurs (e.g. due to manufacturing variations), the spring device ensures that the force applied to the stack is evened out across the contact surface equipped with such spring devices.

[0008] Preferred embodiments can be found in the dependent claims and the entire disclosure, whereby the presentation of the features does not always distinguish in detail between device and method or use aspects; in any case, the disclosure is implicitly to be read with regard to all claim categories. For example, if a specific spring device is described, this is also to be read as a disclosure of a fuel cell stack with such a spring device, and vice versa. Furthermore, the application is not limited to fuel cell stacks; see below for details.

[0009] The first and second suspension elements can each form a contact surface, wherein these contact surfaces are opposite one another with respect to the spring direction, i.e. each point away from the constant force spring elements. The spring device is designed, for example, for compression, in which the contact surfaces are moved towards one another. The spring direction is preferably perpendicular to the contact surface(s). In general, a respective contact surface can, for example, also have a round, in particular circular, or angular, approximately polygonal shape. The contact surfaces can, for example, also be optimized such that several spring devices can be placed next to one another to fill the area as much as possible and can be used in a "parallel connection" - see details below. Rectangular, in particular square, contact surfaces can be particularly preferred.

[0010] In general, the symmetry specifications for the constant-force spring elements initially relate to their "arrangement," i.e., the position of their volume centers of gravity (their basic position, but not necessarily their shape). In other words, the stacked and / or twisted spring elements can generally differ in their shape and / or size. However, the constant-force spring elements arranged according to feature i) and / or feature ii) are preferably identical in construction, i.e., they have the same shape and size. The symmetry conditions then preferably relate to the constant-force spring elements as a whole; thus, one constant-force spring element can be completely mapped onto the other constant-force spring element by a displacement in the translation direction and / or a rotation about the rotation axis.

[0011] The rotational symmetry exists initially "seen in the spring direction," meaning that the constant-force spring elements can be offset from one another in the spring direction despite the rotational symmetry. In other words, the volume centers of gravity, preferably the spring elements as a whole, can be transformed into one another through rotation, possibly in combination with a displacement along the spring direction. The axis of rotation according to feature i) is at least partially parallel to the spring direction, thus has an axial component parallel to it. In other words, it is not perpendicular to the spring direction, but obliquely or preferably parallel to it. The axis of rotation can, in particular, be perpendicular to the contact surface(s) of the suspension elements.

[0012] The translation direction according to feature i) has at least a component in the spring direction, i.e., a directional component that is parallel to the spring direction or coincides with it. If a plurality of constant-force spring elements, i.e., at least three, are arranged translationally symmetrically in the package, their translational symmetry can, in particular, be based on a single translational direction. In other words, preferably all constant-force spring elements of the package are translationally symmetrical to one another in the same translational direction. Regardless of these details, the translational direction can generally be parallel to the spring direction (angle of 0° between them).

[0013] According to a preferred embodiment, however, the translation direction forms an angle of at least 3° with the spring direction, more preferably at least 5° or at least 7°. Possible upper limits can be, for example, at most 80°, 60°, 50°, or 40°; in simplified terms, the translation direction is tilted slightly, but not excessively, relative to the spring direction. The upper limits can be of interest, for example, with regard to a compact structure, for example, in comparison to spring elements placed "next to one another" at an angle of only 90°.

[0014] In a preferred embodiment, the constant-force spring elements of a first symmetry group are rotationally symmetrical to one another, viewed in the spring direction, by an angle of at least 45°, with further possible lower limits at 60°, 70°, 80°, or 85°. Possible upper limits can be, for example, 135°, 120°, 110°, 100°, or 95°. Rotational symmetry of 90° can be particularly preferred. The latter can, in particular, relate to a rectangular / square base or contact surface.

[0015] In a preferred embodiment, the constant-force spring elements of the first symmetry group are partially overlapped in the spring direction, i.e., when viewed from a direction parallel to the spring direction (the overlap refers to a view, not a material fusion). This, in turn, reflects the spatially compact or "interlocked" arrangement, thus allowing for efficient use of space. Relative to the spring direction, the mutually twisted constant-force spring elements of the first symmetry group can be arranged at different "heights," see above.

[0016] According to a preferred embodiment, the constant-force spring elements of a second symmetry group are arranged rotationally symmetrically to one another at an angle of at least 135°, with further lower limits of at least 150°, 160°, 170°, or 175°. Possible upper limits can be, for example, at most 225°, 210°, 200°, 190°, or 185°; an angle of 180° can be particularly preferred. The constant-force spring elements of the second symmetry group can preferably be converted into one another solely by rotation, i.e., without additional translation and / or mirroring.

[0017] The opposing arrangement on both sides allows the spring device to be stabilized laterally, thus preventing, for example, tilting in the spring direction. In general, the stiffness transverse to the spring direction in the force-free case, i.e., at the starting point of the spring force characteristic curve, can already be a factor of 5-10 higher than in the spring direction. In the working range of the spring device, i.e., when the constant-force spring elements are already preloaded, the factor can even be greater than 1000, for example.

[0018] According to a preferred embodiment, the constant-force spring elements in the symmetry groups are each arranged in a first and a second stack. Within each stack, the constant-force spring elements are arranged translationally symmetrically to one another according to feature i), and the rotational symmetry in question then exists between the stacks, for example, by essentially 90° (first symmetry group) or essentially 180° (second symmetry group).

[0019] In a preferred embodiment, the spring device comprises at least four packages, particularly preferably exactly four packages, in which the constant-force spring elements are each arranged translationally symmetrically to one another. Furthermore, the constant-force spring elements of each package are then part of both a first symmetry group and a second symmetry group. Thus, for example, they can be transferred into the package or its constant-force spring elements arranged on the adjacent side edge of the spring device by a rotation through an angle between 45° and 135°, and additionally transferred into the package or its spring elements arranged on the opposite side edge by a rotation through an angle between 135° and 225°.

[0020] According to a preferred embodiment, the suspension elements can be rotated relative to one another, preferably about an axis parallel to the spring direction. This rotatability is present, e.g., when a sufficiently high torque is applied, at least in the force-free state, i.e., when no deformation is applied along the spring direction. The rotatability can be limited to an angular range, e.g., up to a maximum of 10° or a maximum of 5°. In general, the torsional stiffness, i.e., the rotational stiffness about the spring direction, can be somewhat lower than the other torsional stiffnesses. Alternatively, or in addition to the rotatability, the suspension elements can be tilted relative to one another, e.g., by 3°. This, in turn, has no influence on the spring characteristic because the two changes in the spring characteristic of the spring assemblies rotated by 180° compensate for one another. This can be advantageous, for example, in a matrix-like arrangement; see below for details.

[0021] According to a preferred embodiment, each constant-force spring element has a first arc section, a second arc section curved in the opposite direction, and a straight section between the arc sections. As a result of the opposite curvature, one arc section is concave and the other convex towards the same side of the spring element. The arc sections can in particular be circular arc sections, e.g. each extending essentially over a quarter circle. Relative to sectional planes perpendicular to a profile line running from one circular arc section across the straight section to the other circular arc section, the constant-force spring element can preferably have a rectangular cross-section, although other cross-sectional shapes are generally also conceivable.

[0022] In the spring device, the constant-force spring elements are preferably suspended in such a way that, with the offset of the suspension elements in the spring direction, the end faces of the circular arc sections are offset parallel to one another (the end faces facing away from the straight section). Preferably, a width of the constant-force spring element taken parallel to the straight section remains constant. The spring elements are attached to the suspension elements at said end faces or are formed integrally with them; see below for details.

[0023] A preferred embodiment relates to the proportions of the individual sections in the width of the constant-force spring element. This width is taken parallel to the straight section, namely parallel to the profile line there (not transversely); in general, the constant-force spring element can also be twisted, but the profile line preferably lies in one plane. Independent of these details, the first and second curved sections preferably each have a proportion of at least 20%, preferably at least 25%, of this width. Possible upper limits are a maximum of 40%, in particular a maximum of 35%. A proportion of around 30% each can be particularly advantageous, so that the straight section then accounts for around 40%.

[0024] If the straight section is selected to be greater than 40%, slightly increasing characteristic curves can be set in the working range (middle range), for example. Conversely, the characteristic curves can decrease slightly in the middle range if a proportion of less than 40% is selected for the straight section (which can be unstable and therefore less preferred). In general, the characteristic curve of a particular constant force spring element, i.e. its force-displacement curve, can be divided into an initial degressive section, the working range with essentially constant force ("zero stiffness"), and then a progressive section. In the degressive section, the force increases with deformation, although this increase becomes increasingly smaller. Conversely, in the progressive section, the force increases again, with increasing intensity.

[0025] According to a preferred embodiment, the relative mobility of the suspension elements is limited by a stop. For this purpose, for example, a projection facing the other suspension element can be provided on one of the suspension elements, against which the other suspension element rests after a corresponding offset in the spring direction. The stop can be used, for example, to limit the deformation of the constant-force spring elements, thus limiting the material stress. Preferably, each of the suspension elements can form a stop facing the respective other suspension element; upon reaching the stops, the device is in a "block position."

[0026] According to a preferred embodiment, at least two constant-force spring elements are provided as one piece, for example in the form of an additively manufactured part. This integral design can be achieved via the suspension element(s). The constant-force spring elements are thus each formed as one piece with a suspension element or part thereof, preferably with both suspension elements or a part of each. In general, "one piece" means non-destructively separable, which can generally be realized, for example, as any desired material-to-material connection. Additive manufacturing, at least in part, is preferred; thus, the constant-force spring elements are constructed from a previously formless or form-neutral material based on a computer model (see below).

[0027] The application also relates to a fuel cell stack with multiple fuel cells held together by a cover element (see the initial remarks). A spring device disclosed herein is arranged between the fuel cells and the cover element, which proportionally transfers the contact force applied by the cover element to the fuel cells. Preferably, the spring direction is substantially parallel to the stack direction; the contact surfaces of the suspension elements can, for example, be substantially parallel to the plate-shaped fuel cells.

[0028] Preferably, several spring devices can be arranged next to one another between the cover element and the fuel cells, for example, in rows, particularly in a matrix (in rows and columns). These spring devices are then connected in parallel to a certain extent, and in particular, they can then compensate for inhomogeneities across the surface (e.g., in the case of warping of the cover element).

[0029] The application further relates to a method for producing a spring device disclosed herein, wherein at least some of the constant-force spring elements are additively manufactured. Additive manufacturing, i.e., manufacturing by 3D printing, can, for example, open up freedom in geometries. Although, for example, deposition welding is generally also conceivable, additive manufacturing is preferably carried out using a powder bed process, i.e., by selectively melting and thus solidifying a powder layer by layer.

[0030] In general, there can be one or more division levels for additive manufacturing, so in particular the suspension elements can be subdivided into several parts, which are assembled (joined) after additive manufacturing.

[0031] Preferably, the divisions are provided in such a way that the constant force spring elements are each integral with a part of one suspension element at one of their suspension points and are integral with a part of the other suspension element at their other suspension point.

[0032] Alternatively, the spring device can also be manufactured from individual constant-force spring elements, e.g., appropriately bent sheet metal. The constant-force spring elements can be bent and tempered, for example, and then assembled with the suspension elements. For this purpose, they can be inserted into the suspension elements, for example, in appropriate recesses. Additionally or alternatively, they can be joined to them, for example, by gluing or soldering.

[0033] Regardless of the specific manufacturing method, preferred materials can be spring steel or nitinol, for example, whereby the latter can provide targeted stiffness or spring stiffness control via the ambient temperature curve and thus an additional degree of freedom.

[0034] The application also relates to the use of a spring device disclosed herein, in particular in a fuel cell stack. This can serve, for example, as part of a drive unit, i.e., in mobility applications, particularly in aviation. Alternatively, the spring device can also be used, for example, in a shaft coupling or as a guide, for example, in a conventional aircraft engine. Short description of the drawings

[0035] In the following, the invention is explained in more detail using an exemplary embodiment, whereby the individual features within the scope of the independent claims can also be essential to the invention in other combinations and no distinction is made in detail between the different claim categories.

[0036] In detail, Fig. 1 a constant force spring element in an oblique view; Fig. 2 a spring device with several constant force spring elements; Fig. 3 a further view of the device according to Fig. 2 to illustrate the rear structure; Fig. 4 The constant force spring elements of the arrangement according to Fig. 3 in a supervision; Fig. 5 is a further plan view illustrating another package of constant force spring elements arranged on a different level; Fig. 6 a further supervisor who will carry out the additional package in accordance with Fig. 5 and another package at the same level; Fig. 7 a force-displacement diagram to illustrate the spring behavior of the spring device; Fig. 8 a fuel cell stack with several spring devices in a schematic representation. Preferred embodiment of the invention

[0037] Fig. Figure 1 shows an oblique view of a constant-force spring element 1. This is divided into a first curved section 11, a second curved section 12, and a straight section 13 in between. The curved sections 11, 12 are curved in opposite directions; they each account for a share 5.1, 5.2 of approximately 30% of the total width 5 of the constant-force spring element 1. The constant-force spring element 1 is loaded in the Y direction, i.e., essentially by parallel offset of its end faces 1.1, 1.2. This essentially results in a force-displacement diagram analogous to that shown in Fig. 7, i.e. with an essentially constant force in a working range.

[0038] Fig. Figure 2 shows a spring device 20 comprising a first suspension element 21 and a second suspension element 22. These are mounted so as to be movable relative to one another via a plurality of constant-force spring elements 1, specifically in a spring direction 25, which corresponds to a main direction of movement. If the suspension elements 21, 22 are compressed relative to this direction, the summation of the individual constant-force spring elements 1 results in a force-displacement diagram according to Fig. 7. Overall, the spring device 20 has further constant force spring elements, which are arranged in Fig. 2 are not shown for the sake of clarity, but are explained using the other figures.

[0039] The constant force spring elements 1 according to Fig. 2 are combined into a package 31, namely arranged translationally symmetrically to one another in a translation direction 35. This has a portion 35.1 that coincides with the spring direction 25; the translation direction 35 forms an angle 36 of approximately 10° with the spring device 25.

[0040] Facing away from the constant force spring elements 1 in the spring direction 25, the suspension elements 21, 22 each form a contact surface 21.1, 22.1. The spring device 20 is designed for a parallel offset of these contact surfaces 21.1, 22.1 by compression, and it can be mounted over these contact surfaces, for example in a fuel cell stack (see Fig. 8). Furthermore, the suspension elements 21, 22 each form a stop 21a, 22a, which limits the deformability in the spring device 20.

[0041] Fig. 3 shows a Fig. 2 is a fundamentally comparable view, but illustrates additional constant-force spring elements 1, which are arranged behind them and therefore shown in dashed lines. These constant-force spring elements 1 are also combined to form a package 32 with translational symmetry (the direction of translation is not referenced for the sake of clarity). As can be seen from the parts of the suspension elements 21, 22, which are also shown in dashed lines, they are also suspended between the first and second suspension elements 21, 22. The constant-force spring elements 1 of the package 31 are arranged rotationally symmetrically about a rotation axis 40 to the constant-force spring elements 1 of the package 32. In this example, an angle 41 of this rotational symmetry is 180°.

[0042] Fig. 4 shows the constant force spring elements 1 of the packages 31, 32 in a top view, i.e. looking along the rotation axis 40. In conjunction with Fig. Figure 3 illustrates how the individual constant-force spring elements 1 are arranged in staggered fashion in the stacks 31, 32, and how the stacks 31, 32 are rotated relative to each other around the rotation axis 40. With this rotational symmetry of 180°, the constant-force spring elements 1 are part of a second symmetry group 52.

[0043] Fig. 5 illustrates a first symmetry group 51, also based on the previously discussed package 31 with the constant force spring elements 31. In addition, however, a further package 33 is shown, which also comprises several constant force spring elements 1. However, these are arranged at a different height with respect to the spring direction 25, i.e., in a sense, below the package 31. With respect to the Fig. 2 and Fig. 3, this package is arranged at the rear of the section at reference number 22.

[0044] In the first symmetry group 51, the constant-force spring elements 1 are also rotationally symmetrical to one another in the spring direction 25, namely, in this case, by an angle 61 of 90° (around the rotation axis 50). Due to the offset, an additional translation in the spring direction 25 is necessary to transfer the constant-force spring elements of the stacks 31, 33 into one another.

[0045] Fig. Finally, Figure 6 shows, in addition to the package 33 with the constant force spring elements 1, another package 34 with constant force spring elements 1, which are arranged at the same level or height. Within a respective package 33, 34, the constant force spring elements 1 are arranged translationally symmetrically to one another, and the constant force spring elements 1 of the packages 33, 34 in turn form a second symmetry group 52. They can therefore be converted into one another by a 180° rotation about the rotation axis 40. If one were to start from the Fig. 6 upper side of the arrangement, this would result in a course of the constant force spring elements 1 as in Fig. 3, only offset downwards.

[0046] Fig. Figure 7 illustrates the behavior of the spring device 1 in a force-displacement diagram 70. The displacement S is plotted on the x-axis, and the force F on the y-axis. This increases in a preload range 71, but then remains constant in a working range 72 upon further deformation. However, it can also decrease or increase slightly there, although the latter may be preferred for fail-safe reasons (no bottoming out). Only in a progressive range 73 does a further deformation lead to a significant increase in the force F. The vertical line finally indicates the blocking position.

[0047] Fig.Figure 8 shows a schematic section of a fuel cell stack 80 with multiple fuel cells 81. The fuel cells 81 are arranged consecutively in a stacking direction 82, with a bipolar plate 83 positioned between each two fuel cells 81. A monopolar plate 84 adjoins the end; like the bipolar plates 83, this plate is flowed through by gas, e.g., oxygen or hydrogen, for the combustion process.

[0048] This arrangement is held together by a cover element 85, which is penetrated by tension elements 86 and clamped under tension. The stack at the opposite end (not shown here) can be constructed analogously, i.e., a cover element can also be clamped. As shown by the dashed line on the cover element 85, the clamping can result in a warping of the cover element 85, particularly in larger geometries. Therefore, several spring devices 20 are arranged between the cover element 85 and the stacked fuel cells 81, so that a constant contact force can be applied to the stacked fuel cells 81 despite any deviation in the deformation. LIST OF REFERENCE SYMBOLS 1 constant force spring element(s) 1.1, 1.2. Front sides 5 Total width of the constant force spring element 5.1, 5.2 Share (at least 20% and at most 40%) 11 First arch section 12 Second arch section 13 Straight section 20 spring device 21 First suspension element 21.1, 22.1 Contact surfaces 21a, 22a stop 22 Second suspension element 25 Spring direction 31-34 packages 35 Translation direction 35.1 Share in the spring direction 36 angles (around 10°, minimum 3° and maximum 80°) 40, 50 axes of rotation 41 angles (180°, minimum 135° and maximum 225°) 51 First symmetry group 52 Second symmetry group 61 angles (90°, minimum 45° and maximum 135°) 70 Force-displacement diagram 71 Preload range 72 work area 73 progressive area 80 fuel cell stacks 81 fuel cells 82 Stacking direction 83 Bipolar plate 84 Monopolar plate 85 Cover element 86 tension element(s)

Claims

[1] Spring device (20) with a first suspension element (21), a second suspension element (22) and a plurality of constant force spring elements (1), wherein the first and second suspension elements (21, 22) are suspended via the constant force spring elements (1) in a spring direction (25) relative to each other, and wherein at least some of the constant force spring elements (1) i) are arranged translationally symmetrically to one another in a package (31-34) in a translation direction (35), which has at least a portion (35.1) in the spring direction (25), and / or ii) viewed in the spring direction (25) are arranged rotationally symmetrically to one another about an axis of rotation (40, 50) which is at least partially parallel to the spring direction (25). [2] Spring device (20) according to claim 1, wherein the translation direction (35) forms an angle (36) of at least 3° and at most 80° with the spring direction (25). [3] Spring device (20) according to claim 1 or 2, wherein the constant force spring elements (1) of a first symmetry group (51) are arranged rotationally symmetrically to one another in the spring direction (25) by an angle (61) which is at least 45° and at most 135°. [4] Spring device (20) according to claim 3, wherein the constant force spring elements (1) of the first symmetry group (51) are provided partially overlapping in the spring direction (25). [5] Spring device (20) according to one of the preceding claims, in which the constant force spring elements (1) of a second symmetry group (52) are arranged rotationally symmetrically to one another in the spring direction (25) by an angle (41) which is at least 135° and at most 225°. [6] Spring device (20) according to one of claims 3 to 5, wherein the constant force spring elements (1) in the first and / or second symmetry group (51, 52) are each arranged in a plurality of packages (31-34) according to feature ii). [7] Spring device (20) according to claim 6, which has a total of at least four packages (31-34) according to feature ii), wherein each package (31-34) is part of a first symmetry group (51) according to claim 3 and at the same time part of a second symmetry group (52) according to claim 5. [8] Spring device (20) according to one of the preceding claims, in which the suspension elements (21, 22) are rotatable relative to one another, in particular about an axis parallel to the spring direction (25). [9] Spring device (20) according to one of the preceding claims, in which a respective constant force spring element (1) - a first arc section (11), - a second arc section (12) curved in the opposite direction, and - has a straight section (13) therebetween. [10] Spring device (20) according to claim 9, wherein the first and the second arc section (11, 12) each have a proportion (5.1, 5.2) of at least 20% and at most 40% of a width (5) of the constant force spring element (1) taken parallel to the straight section (13). [11] Spring device (20) according to one of the preceding claims, in which the relative mobility of the suspension elements (21, 22) in the spring direction (25) is limited by a stop (21a, 22a). [12] Spring device (20) according to one of the preceding claims, in which at least two constant force spring elements (1) are provided in one piece with one another, in particular are an additively manufactured part. [13] Fuel cell stack (80), with fuel cells (81) arranged one after the other in a stacking direction (82), a cover element (85) which follows the fuel cells (81) in the stacking direction (82) and holds them together, and a spring device (20) according to one of the preceding claims, wherein the spring device (20) is arranged between the fuel cells (81) and the cover element (85). [14] Method for producing a spring device (20) according to one of claims 1 to 12 or a fuel cell stack (80) according to claim 13, in which at least some of the constant force spring elements (1) are manufactured additively. [15] Use of a spring device (20) according to one of claims 1 to 12 in a fuel cell stack (80), in a shaft coupling or in a guide.

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