Fuel cell

Abstract

Fuel cell, comprising: a base plate (11); a stack (20) bearing against the base plate (11); and a compression system, which comprises: a bearing plate (30), movable and bearing against the stack (20); springs (50), bearing against the bearing plate (30); and a flange (40), bearing against the springs (50). So that the fuel cell is particularly stable over time, the fuel cell comprises a first sliding connection (70), for guiding the bearing plate (30) in sliding movement relative to the base plate (11), and pulling plates (60) separated from one another and having anchors fastening them to the base plate (11) and to the flange (40) for holding the stack (20) in compression between the base plate (11) and the bearing plate (30) via the anchors, under the action of the springs (50).

Description

[0001] TITLE: Fuel Cell

[0002] The invention relates to a fuel cell.

[0003] US2020144651 A1 describes a fuel cell with a stack consisting of electrochemical cells. The electrochemical cells are stacked and held in compression along a stacking direction, between two end plates. To maintain the stack in compression, the end plates are bordered by a holding system, comprising transverse members, disc springs and rods. The transverse members are arranged on either side of the end plates and are connected to each other by rods, which extend from one end of the stack to the other, parallel to the stacking direction. At each end of the stack, under the action of the rods, the transverse members are held in abutment against the end plate, with interposition of the disc springs and the pressure distribution plate between the transverse members and the end plate, on each side of the stack. A casing surrounds the assembly.

[0004] This known fuel cell has the disadvantage that, in practice, the compression of the stack may lack precision and / or be unstable over time, in particular under the effect of axial deformations of the stack caused by thermal stresses, which may have the consequence of generating transverse stresses on the stack and the compression maintenance system.

[0005] The invention aims to resolve the drawbacks of the prior art, by proposing a new fuel cell which is particularly stable over time.

[0006] The invention relates to a fuel cell comprising: a base plate; a stack, which comprises electrochemical cells stacked in a compression direction and which bears against the base plate in the compression direction; and a compression system. The compression system comprises: a support plate, which is movable relative to the base plate parallel to the compression direction and which bears against the stack in the compression direction; springs, which bear against the support plate in the compression direction; and a flange, which bears against the springs in the compression direction. According to the invention, the fuel cell comprises a first sliding connection, via which the support plate is guided in sliding relative to the base plate, in the compression direction.According to the invention, the compression system further comprises pull plates, separated from each other, each pull plate comprising anchors by means of which the pull plate is attached to the base plate and to the flange, the pull plates thus ensuring that the stack is held in compression between the base plate and the support plate, in the compression direction, by means of the anchors, under the action of the springs bearing on the flange.

[0007] An idea behind the invention is to maintain the position of the support plate transversely using the sliding connection, in order to ensure that, depending on the compression direction, the support plate remains perfectly aligned with the base plate and is unlikely to unbalance the distribution of the pressing force applied to the stack by the flange via the springs. The pulling plates, with their plurality of anchors, take up most of the torsional stresses that could be applied to the stack and the compression system. The stability of the compression of the stack over time is therefore improved.

[0008] Preferably, the first sliding connection comprises a primary slider, attached to the backing plate, and a secondary slider, attached to the base plate, the primary slider and the secondary slider being received within each other, so as to slide relative to each other in the compression direction, thereby guiding the sliding of the backing plate relative to the base plate.

[0009] Preferably, the fuel cell comprises a housing, which contains the stack and the compression system and the flange and which is fixedly attached to the base plate. Preferably, the secondary slider is fixedly attached to the base plate by being fixedly attached to the housing, preferably at the height of the flange or the springs along the compression direction.

[0010] Preferably, each pull plate comprises a common tie rod and individual tie rods, which carry the anchors, each individual tie rod being attached to the common tie rod and having an adjustable position relative to the common tie rod along the compression direction, for adjusting the position of the anchors by means of which the pull plate is attached to the flange relative to that of the anchors by means of which the pull plate is attached to the base plate.

[0011] Preferably, in order that the respective position of the individual tie rods relative to the common tie rod is adjustable, each individual tie rod is connected to the common tie rod by a helical connection parallel to the compression direction.

[0012] Preferably, each draw plate comprises stringers, parallel to the compression direction.

[0013] Preferably, each draw plate comprises a cross member, rigidly connecting the side members together by being fixedly connected to said side members, the cross member being arranged between the flange and the base plate. Preferably, for each draw plate, at least two side members are spaced apart by an inter-side member distance which is greater than 50% of a width of the stack, the inter-side member distance being measured perpendicular to the compression direction and the width of the stack being measured parallel to the inter-side member distance.

[0014] Preferably, each spar is axially aligned, along the compression direction, with one of the anchors of the pull plate, and preferably with two of the anchors of the pull plate, being arranged between said two anchors.

[0015] Preferably, at least one of the anchors comprises at least one wing, which extends radially from said spar and which bears against the base plate in the opposite direction to the compression direction, for attaching the pull plate to the base plate, said at least one wing being arranged in a plate plane along which the spars extend.

[0016] Preferably, for each pull plate, the anchors comprise primary anchors, through which the pull plate is attached to the base plate, and secondary anchors, through which the pull plate is attached to the flange.

[0017] Preferably, the draw plates comprise a first draw plate and a second draw plate, which are parallel to each other.

[0018] Preferably, the first pull plate and the second pull plate are arranged on either side of the stack, opposite each other relative to the stack.

[0019] Preferably, wherein the fuel cell comprises a second sliding connection, by means of which the flange is slidably guided relative to the support plate, in the compression direction.

[0020] Preferably, the flange is made of different parts independent of each other.

[0021] The invention and other advantages thereof will appear in the light of the following description of embodiments in accordance with its principle, made with reference to the appended figures in which:

[0022] [FIG 1] Figure 1 shows a longitudinal section of a fuel cell according to one embodiment of the invention.

[0023] [FIG 2] Figure 2 is a perspective view of the fuel cell of Figure 1.

[0024] [FIG 3] Figure 3 is a perspective view, from another angle, of a subassembly belonging to the fuel cell of the preceding figures, including a base plate and a compression system.

[0025] [FIG 4] Figure 4 is a partial side view of the subassembly of Figure 3.

[0026] [FIG 5] Figure 5 is a partial perspective view of the subassembly of Figures Figures 1 and 2 show a fuel cell, which comprises a base plate 11, a stack 20 and a compression system. Preferably, the fuel cell comprises a casing 10. The compression system comprises a backing plate 30, a flange 40, springs 50 and puller plates 60, here only two puller plates 60. Figures 3 to 5 show the fuel cell without the casing 10 and without the stack 20.

[0027] A compression direction X10, a first transverse direction Y10 and a second transverse direction Z10 are defined. These three directions are perpendicular to each other and fixed relative to the base plate 1 1 .

[0028] The fuel cell is preferably used in a vehicle, in particular a motor vehicle, such as a car or a truck, or other rolling vehicle, to provide the electrical power supply to one or more motors providing propulsion for said vehicle.

[0029] The stack 20 is represented by broken lines in Figures 3 and 4. The stack 20 is a stack of electrochemical cells 21, shown schematically in Figure 1, but which are not individually represented for the sake of simplification, since the stack 20 comprises for example between 250 and 400 cells 21. Each electrochemical cell 21 is for example constituted by an anode and a cathode, separated by a polymer membrane allowing the passage of protons from the anode to the cathode. When using the fuel cell, each anode of the stack 20 is supplied with fuel, for example dihydrogen, and each cathode of the stack 20 is supplied with oxidant, for example oxygen or air.

[0030] To form the stack 20, the electrochemical cells 21 are stacked, i.e. superimposed, along the compression direction X10. Each cell 21 extends along an individual plane, perpendicular to the direction X10. Preferably, when the fuel cell is in operation, for example in the vehicle, the compression direction X10 is approximately horizontal.

[0031] For this stack 20, a central axis X20 is defined which passes through the stack 20 and which is parallel to the direction X10. The axis X20 also passes through the base plate 11, the support plate 30 and the flange 40.

[0032] The casing 10 surrounds and protects the stack 20, the compression system and the base plate 11, i.e. it contains these elements. The casing 10 comprises a transverse wall 12 and a longitudinal wall 13. The transverse wall 12 is perpendicular to the direction X10. The wall 12 is crossed by the axis X20. The longitudinal wall 13 is parallel to the direction X10. The longitudinal wall 13 is a peripheral wall, i.e. tubular, which surrounds the stack 20, extending to the wall 13, in the direction X10, and beyond the flange 40, in the opposite direction to the direction X10. The longitudinal wall 13 surrounds the axis X20. The wall 12 is fixedly attached to the wall 13, so as to close the casing 10 at one end of the wall 13. The stack 20 is arranged inside the casing 10, in particular inside the wall 13. Overall, the walls 12 and 13 are arranged so that the casing 10 has a generally parallelepiped shape.

[0033] Preferably, the transverse wall 12 receives the base plate 11 in support, in the compression direction X10. The base plate 11 is oriented perpendicular to the direction X10 and is therefore in flat support against the wall 12. Here, the base plate 11 is fixed to the wall 12, for example using screws. More generally, it is advantageously provided that the base plate 11 is fixedly attached to the casing 10.

[0034] The base plate 11 here serves as a fixed end plate for the stack 20, in that the stack 20 bears, flat, in the compression direction X10, against the base plate 11. However, it could be provided that the stack 20 comprises a separate fixed end plate, by means of which the stack 20 would bear against the base plate 11.

[0035] Preferably, the base plate 11 comprises openings which can be crossed by connectors, not shown, provided to be connected to fluid circulation conduits, thus making it possible to supply the stack 20 with the fuel, the oxidizer, a possible cooling fluid, and to evacuate the reaction products if there are any. Corresponding openings are advantageously provided on the transverse wall 12.

[0036] The stack 20 is received between the support plate 30 and the base plate 11, being compressed, in the direction X10, between these two plates 11 and 30. In particular, the plate 30 applies a pressing force F30 on the stack 20, directed in the direction X10, the stack 20 bearing against the base plate 11. The support plate 30 bears against the stack 20 in the direction X10, opposite the base plate 11. The support plate 30 is oriented perpendicular to the direction X10 and bears flat against the stack 20.

[0037] The support plate 30 and the base plate 11 being in flat support against the stack 20, they advantageously ensure that the mechanical stresses resulting from the force F30 are distributed over the end surfaces of the stack 20.

[0038] The support plate 30 is movable relative to the base plate 11 parallel to the compression direction X10, so that the distance between the support plate 30 can change during use of the fuel cell, over time, and thus adapt to dimensional variations of the stack 20, likely to be caused by different factors, in particular thermal factors.

[0039] The fuel cell comprises a sliding connection 70 for the support plate 30, called the plate sliding connection 70, formed inside the housing 10. The support plate 30 is guided in sliding relative to the base plate 11, in the compression direction X10, by this sliding connection 70. In other words, the plate sliding connection 70 prevents the support plate 30 from pivoting as a whole relative to the base plate 11 and prevents the plate 30 from moving transversely to the direction X10, in particular in the directions Y10 and Z10, relative to the base plate 11. The plate sliding connection 70 thus stabilizes the support plate 30 and the stack 20 during assembly of the fuel cell, but also during use of the fuel cell.Thanks to these provisions, the deformations of the stack 20, in particular under the effect of the heat that it is likely to generate, as well as possible vibrations, are therefore less likely to affect the integrity of the fuel cell.

[0040] In the present example, as seen in Figures 1 and 2, the plate sliding connection 70 comprises primary plate sliders 71 and secondary plate sliders 72, distributed in pairs. In the present example, two pairs of plate sliders 71 and 72 are provided. At a minimum, a single pair with a primary plate slider 71 and a secondary plate slider 72 is provided. Each primary plate slider 71 is attached, preferably fixedly, to the support plate 30. Each secondary plate slider 72 is attached, preferably fixedly, to the base plate 11. For this, preferably, the secondary plate slider 72 is fixedly attached to the casing 10, itself fixedly attached to the base plate 11.For each pair, the plate sliders 71 and 72 are received one inside the other, so as to slide relative to each other in the direction X10, to thereby guide the sliding of the support plate 30 relative to the base plate 11. Each pair of plate sliders 71 and 72 is advantageously arranged, perpendicular to the direction X10, between the wall 13 of the casing and the flange 40, and, in the direction X10, at the height of the flange 40.

[0041] In the present example, for a given primary slider 71, possibly for each primary plate slider 71, the primary plate slider 71 is constituted by a rod, parallel to the direction X10 and fixedly attached to the plate 30 by being attached to the plate 30. For example, as visible in FIG. 1, the rod of a given primary plate slider 71 comprises a threaded end, received in a tapped orifice provided in the plate 30, and a smooth end, to guide the sliding. The rod projects for example from the plate 30 in the opposite direction to the direction X10 relative to the stack 20, and can extend beyond the flange 40.

[0042] In the present example, each secondary plate slider 72 comprises a sliding bore, parallel to the direction X10 and fixedly attached to the wall 13 of the casing 10, so as to be fixedly attached to the base plate 11 via the casing 10. Preferably, all the sliding bores are formed at the same height along the direction X10, being distributed in a plane perpendicular to the direction X10. Preferably, for a given secondary plate slider 72, possibly for each secondary plate slider 72, the sliding bore is formed through a respective lug 14 belonging to the casing 10. Each lug 14 is for example directly fixedly attached to the wall 13, on the inside of the casing 10, approximately at the height of the flange 40.For a given secondary plate slide 72, possibly for each secondary plate slide 72, it is also possible to provide a sliding sleeve 15, forming the sliding bore and being fixedly received through the corresponding ear 14. The sliding sleeve 15 advantageously makes it possible to obtain that the sliding of the rod is more precise than with a sliding bore which would be provided directly through the ear 14 and / or makes it possible to have, for the sliding bore, a material less sensitive to wear and / or promoting sliding of the rod within it in the direction X10.

[0043] Several springs 50 are provided, here nine springs 50. Here each spring 50 is advantageously a compression spring, oriented parallel to the direction X10. Here each spring 50 is a helical spring, but another type of spring could be provided, for example made up of Belleville washers, that is to say a spring washer, generally of truncated cone shape. Each spring 50 bears against the support plate 30 along a support axis which is specific to it and which is parallel to the direction X10. In other words, the support plate 30 is interposed between the stack 20 and the springs 50, along the direction X10. Preferably, the springs 50, and therefore their respective support axes, are regularly distributed over the surface of the support plate 30, so that the force F30 can be distributed by the support plate 30 over the stack 20, under the collective action of the springs 50.Here, for example, three rows of three springs 50 are provided, forming a grid whose lines and columns are parallel to the directions Y10 and Z10.

[0044] As visible in Figures 1 and 4, each spring 50 is interposed between the flange 40 and the support plate 30, in the direction X10. In other words, the flange 40 bears against each spring 50, in the direction X10. It is under the action of the flange 40 that the springs 50 bear on the support plate 30 so that the support plate 30 applies the pressing force F30. By bearing on the flange 40 and being elastically deformed in the direction X10, the springs 50 collectively apply, by elasticity, forces on the support plate 30, directed in the direction X10. The support plate 30 transmits these forces to the stack 20, in the form of the pressing force F30.

[0045] Preferably, the pairs of plate sliders 71 and 72 are distributed at the transverse ends of the plate 30. In a plane perpendicular to the direction X10, it is advantageously provided that the two pairs of plate sliders 71 and 72 are arranged on either side of the springs 50, or possibly between the springs 50 of one of the spring columns arranged on the outside. It is advantageously provided that, in the plane perpendicular to the direction X10, the pairs of plate sliders 71 and 72 border the flange 40, or possibly pass through the flange 40 near a peripheral edge of said flange 40. For example, the first pair of plate sliders 71 and 72 is arranged in a transverse direction oblique to, relative to the second pair of plate sliders 71 and 72, the oblique transverse direction being oblique to the directions Y10 and Z10 and perpendicular to the direction X10.

[0046] Preferably, the fuel cell comprises a sliding connection 80 between the support plate 30 and the flange 40, called the sliding flange connection 80, formed inside the casing 10. The flange 40 is guided in sliding relative to the support plate 30, in the compression direction X10, by this sliding flange connection 80. In other words, the sliding flange connection 80 prevents the flange 40 from pivoting as a whole relative to the plate 30, and prevents the flange 40 from moving transversely relative to the direction X10, in particular in the directions Y10 and Z10, relative to the plate 30. The sliding flange connection 80 thus makes it possible to stabilize the flange 40 and the stack 20 during the manufacture of the fuel cell, but also during the use of the fuel cell.

[0047] In the present example, as seen in Figures 1, 2 and 4, the flange sliding connection 80 comprises primary flange sliders 81 and secondary flange sliders 82, distributed in pairs.

[0048] In the present example, two pairs of flange slides 81 and 82 are provided. At a minimum, a single pair is provided with a primary flange slider 81 and a secondary flange slider 82. Each primary flange slider 81 is attached, preferably fixedly, to the backing plate 30. Each secondary flange slider 82 is attached, preferably fixedly, to the flange 40. For each pair, the flange sliders 81 and 82 are received one inside the other, so as to slide relative to each other in the direction X10, to thereby guide the sliding of the backing plate 30 relative to the flange 40. In the present example, for a given primary flange slider 81, possibly for each primary flange slider 81, the primary flange slider 81 is constituted by a rod, parallel to the direction X10 and fixedly attached to the plate 30 by being attached to the plate 30.Each rod protrudes, for example, from the plate 30 towards the flange 40.

[0049] In the present example, for a given secondary flange slide 82, possibly for each secondary flange slide 82, the secondary flange slide 82 comprises a sliding bore, parallel to the direction X10. Here the sliding bore is fixedly attached to the flange 40 by being formed by the flange 40 itself. Each sliding bore is advantageously open in the direction of the plate 30 and in alignment with the corresponding rod, along the direction X10, so as to slidably receive said rod.

[0050] Preferably, the pairs of flange sliders 81 and 82 are distributed over the surface of the plate 30. Here, it is provided that the two pairs of flange sliders 81 and 82 are arranged between the springs 50. In particular, as visible in FIG. 2, the pairs of flange sliders 81 and 82 are arranged on either side of a spring 50 arranged in the middle of the column of springs 50 arranged in the center, diametrically opposite relative to this central spring 50. The central spring 50 is advantageously crossed by the axis X20. A first pair of flange sliders 81 and 82 is disposed between the central spring 50 and another spring 50, disposed in one corner of the spring grid 50. The second pair of flange sliders 81 and 82 is disposed between the central spring 50 and another spring 50, disposed in an opposite corner of the spring grid 50.For example, the first pair is arranged in an oblique transverse direction relative to the central spring 50, the oblique transverse direction being oblique to the directions Y10 and Z10 and perpendicular to the direction X10. For example, the second pair is arranged in the same oblique direction relative to the central spring 50, but in the opposite direction relative to the first pair.

[0051] Preferably, when two pairs of plate sliders 71 and 72 and two pairs of flange sliders 81 and 82 are provided, they are arranged according to a quadrilateral drawn in projection in a plane perpendicular to the X10 direction, with a successive alternation of a pair of plate sliders 71 and 72 and a pair of flange sliders 81 and 82 on its perimeter. In other words, the two pairs of plate sliders 71 and 72 are at the ends of a first diagonal of the quadrilateral and the two pairs of flange sliders 81 and 82 are at the ends of a second diagonal of the quadrilateral, intersecting the first near the center of the flange 40 and / or the central spring 50. In the present example, the flange 40 forms an openwork frame which extends, generally, along a plane perpendicular to the X10 direction. However, the flange 40 could be in the form of a non-perforated plate.

[0052] As visible in Figure 2, the flange 40 comprises for example a main arm 41, parallel to the direction Z1, and secondary arms parallel to the direction Y1, here secondary arms 42, 43, 44, 45, 46 and 47. The secondary arms 42 to 47 are rigidly connected to the main arm 41, for example by forming a single piece, in one piece with the main arm 41. For example, the secondary arms 42, 43 and 44 extend from the main arm 41 in the direction Y10, being parallel to each other and distant from each other. For example, the secondary arms 45, 46 and 47 extend from the main arm 41 in the opposite direction to the direction Y10, being parallel to each other and distant from each other. Here the secondary arms are distributed in pairs, in that, along the Y10 direction, arm 42 is aligned with bottom 45, arm 43 is aligned with arm 46 and arm 44 is aligned with arm 47.Preferably, as many pairs of arms are provided as there are columns of springs 50. Here, there are three columns of three springs 50, so that three pairs of secondary arms are provided.

[0053] Each secondary arm 42 to 47 receives one of the springs 50 as support, in the opposite direction to the direction X10. The secondary arms 42, 43 and 44 respectively receive the springs 50 of a first column as support. The secondary arms 45, 46 and 47 respectively receive the springs 50 of a second column as support. The main arm 41 receives, in the opposite direction to the direction X10, respectively the springs of a third column, arranged between the first column and the second column.

[0054] Preferably, each bore forming one of the flange slides 82 is formed on a portion of the flange 40 which connects two secondary arms and the main arm to each other, this portion being for example formed in one piece with said arms. Here, one of the bores is formed on a portion of the flange 40 which connects the arm 41, the arms 42 and 43, and the other of the bores is formed on a portion of the flange 40 which connects the arm 41, the arms 46 and 47.

[0055] As seen previously, independently of the embodiment of the flange 40, each elastically deformed spring 50 bears on the flange 40, in the opposite direction to the direction X10, to be able to collectively apply forces to the support plate 30, so that the support plate 30 itself applies the force F30 to the stack 20.

[0056] The flange 40 itself is retained relative to the base plate 11, in the opposite direction to the X10 direction, by the draw plates 60, each draw plate 60 being attached, on the one hand, to the flange 40, and on the other hand, to the base plate 11. By being thus retained by the pulling plates 60, during use of the fuel cell, the flange 40 is fixed relative to the base plate 11 in the direction X10, unlike the support plate 30 which is likely to move relative to the base plate 11 in the direction X10, under the effect of the deformations of the stack 20. Nevertheless, as explained below, the position of the flange 40 can be adjusted relative to the base plate 11 in the direction X10, using the pulling plates 60, in order to adjust the pressing force applied by the springs 50 on the stack 20.

[0057] Preferably, provision is made for only the pulling plates 60 to retain the flange 40 in the opposite direction to the direction X10. In particular, advantageously no other members, such as tie rods or rods, are provided to retain the flange 40 relative to the base plate 11, parallel to the direction X10. In particular, provision is not made for the casing 10 to retain the flange 40 relative to the base plate 11, parallel to the direction X10. To apply the force F30, the support plate 30 is attached to the base plate 11, being retained relative to the base plate 11 by a chain of elements constituted by, successively, the pulling plates 60, the flange 40 and the springs 50.

[0058] In the present example, exactly two pull plates 60 are provided, as seen in Figures 1 and 3. More than two pull plates 60 could be provided. However, an advantage of providing pull plates 60 rather than individual tie rods such as rods is to facilitate the assembly of the fuel cell by limiting the number of parts to be assembled. In other words, it may be preferable to provide as few pull plates 60 as possible. Indeed, each pull plate 60 is capable of providing on its own a function similar to that which would have been provided by a plurality of separate individual rods.

[0059] The pull plates 60 are distributed around the stack 20. In particular, the pull plates 60 are distributed around the axis X20. In the case where an even number of plates 60 is provided, the pull plates 60 are preferably arranged in pairs of plates 60, where, for each pair, the plates 60 are arranged on either side of the stack 20, preferably diametrically opposite relative to the stack 20, in particular relative to the axis X20. Preferably, for each pair of plates 60, the two plates 60 are parallel to each other.

[0060] The pull plates 60 are seen in more detail in Figures 3 to 5. Each pull plate 60 has a generally flat shape, and extends parallel to the direction X10. Here, each pull plate 60 extends along a respective plate plane P60, which is therefore parallel to the direction X10, and is here perpendicular to the direction Y10. The stack 20, the support plate 30 and the springs 50 are arranged between the plates 60. Each pull plate 60 is separate from any other pull plate 60. In other words, the plates 60 are not attached to each other, other than by means of the base plate 11 and the flange 40.

[0061] Each pull plate 60 comprises anchors, including primary anchors 61 and secondary anchors 62. The primary anchors 61 attach the pull plate 60 to the base plate 11, along the X10 direction, retaining the pull plate 60 relative to the base plate 11 in the opposite direction to the X10 direction. The secondary anchors 62 attach the pull plate 60 to the flange 40, along the X10 direction, retaining the pull plate 60 along the X10 direction. Thanks to these arrangements, the pull plates 60 ensure that the stack 20 is held in compression between the base plate 11 and the support plate 30, along the compression direction X10, by means of the primary anchors 61 and the secondary anchors 62, under the action of the springs 50 bearing on the flange 40.In other words, it is in particular thanks to the pulling plates 60, retaining the flange 40 relative to the base plate 11, that the force F30 can be applied by the support plate 30 on the stack 20, under the action of the springs 50 bearing on the flange 40.

[0062] Preferably, each draw plate 60 advantageously occupies in width, at least 50%, or even at least 70% of a width L20 of the stack 20, the width L20 of the stack being measured perpendicular to the direction X10 and parallel to the draw plate 60 concerned.

[0063] Each pull plate 60 also advantageously comprises a single common tie rod 63 and several individual tie rods 64. Each individual tie rod 64 is attached to the common tie rod 63, preferably with the possibility of adjusting the position of each individual tie rod 64 relative to the common tie rod 63, in the direction X10. The common tie rod 63 advantageously carries all the primary anchors 61 of the pull plate 60, while each individual tie rod 64 advantageously carries only one of the secondary anchors 62 of the pull plate 60, so that any secondary anchor 62 of the plate 60 is carried by one of the individual tie rods 64 of said plate 60. Alternatively, it could be provided that the primary anchors 61 are carried by the individual tie rods 64 while the secondary anchors are carried by the common tie rod 63. Alternatively, another distribution of the anchors 61 and 62 between the tie rods 63 and 64 can also be envisaged.

[0064] Along the direction X10, the common tie rod 63 advantageously occupies at least 50%, or even at least 70% and even, preferably, at least 90% of the length of the pulling plate 60, while the remaining percentage of the length of the plate 60 is occupied by the individual tie rods 64. Preferably, the common tie rod 63 advantageously occupies at least 50%, or even at least 70% of the width L20 of the stack 20, the width L20 being measured perpendicular to the direction X10 and parallel to the plate 60 concerned.

[0065] In the present example, carrying the primary anchors 61 at one end of the pull plate 60, the common tie rod 63 extends from the primary anchors 61, i.e. from the base plate 11, in the opposite direction to the X10 direction, i.e. in the direction of the flange 40. In the present example, carrying the secondary anchors 62 at another end of the plate 60, the individual tie rods 64 extend from the secondary anchors 62, i.e. from the flange 40, in the X10 direction, i.e. in the direction of the base plate 11. Each individual tie rod 64 is attached to the common tie rod 63, between the base plate 11 and the flange 40, i.e. between the anchors 61 and 62.

[0066] The common tie rod 63 is in the form of a solid plate or an openwork lattice, which extends along the plane P60 of the pull plate 60. In the present example, the common tie rod 63 is in the form of an openwork lattice, which has the advantage of lightening the common tie rod 63.

[0067] Preferably, the common tie rod 63 comprises side members 65, here three side members 65. Each side member 65 is a rigid rectilinear member. Each side member 65 is parallel to the direction X10. The side members 65 are arranged along plane P60 of the pull plate 60.

[0068] Preferably, all the side members 65 are of the same length. Each side member 65 extends to one of the individual tie rods 64, which extends the side member 65 parallel to the direction X10. Each side member 65 ends between the flange 40 and the base plate 11, preferably at the height of the support plate 30. Each individual tie rod 64 is attached to the common tie rod 63 via one of the side members 65. Along the direction X10, each side member 65 advantageously reaches the base plate 11 and preferably passes through the base plate 11. At the height of the base plate 11, each side member 65 advantageously carries one of the primary anchors 61. Preferably, along the direction X10, each spar is axially aligned with the primary anchor 61 which it carries and with the secondary anchor 62 carried by the individual tie rod 64 attached to this spar 65.In other words, each spar 65 is axially aligned, along the compression direction X10 with two of the anchors 61 and 62 of the pull plate 60, being arranged between said two anchors 61 and 62. Thus, each spar 65 and the corresponding individual tie rod 64 are stressed exclusively in tension by the anchors 61 and 62 parallel to the direction X10, if the manufacturing and assembly tolerances are ignored. In general, the pull plate 60 is thus stressed exclusively in tension, if the manufacturing and assembly tolerances are ignored. Preferably, for each pull plate 60, if not for at least one of them, at least two side members 65, namely the side members placed at the edges of the pull plate 60, are separated by an inter-side member distance L65 which is greater than 50%, or even greater than 70%, of the width L20 of the stack 20.The inter-spar distance L65 is measured perpendicular to the direction X10, along the plane P60 of the plate 60, and parallel to the width L20 of the stack 20. More generally, parallel to the width L20, the plate 60 is particularly wide, the anchors 61 are particularly distant from each other, and the anchors 62 are particularly distant from each other, so that the plate 60 effectively absorbs torsional or bending forces which could be applied to the stack 20.

[0069] Preferably, each pulling plate 60 comprises one or more crosspieces 66, here three crosspieces 66. Each crosspiece 66 is oriented transversely, preferably perpendicularly, relative to the direction X10, preferably extending in the plane P60. Each crosspiece 66 is thus transverse, preferably perpendicular, to the longitudinal members 65. Each crosspiece 66 rigidly connects at least two longitudinal members 65 to each other, if not all the longitudinal members 65 of the plate 60 to each other, as in the present example. Overall, the longitudinal members 65 of the plate 60 are rigidly attached to each other by the crosspieces 66, so that the common tie rod 63 is rigid. For each plate 60, the longitudinal members 65 and the crosspieces 66 form the aforementioned lattice. It can be provided, as in the present example, that openings are delimited by the side members 65 and cross members 66 of the plate 60, making this plate 60 an openwork plate.Alternatively, provision could be made for these openings to be filled, to form a solid plate. The crosspieces 66 rigidly connecting the longitudinal members 65 make it possible to absorb bending and / or shear forces likely to be applied to the stack 20, so that the assembly is particularly stable and strong. Preferably, at least one crosspiece 66 is arranged between the flange 40 and the base plate 11, in particular between the anchors 61 and 62, in particular between the ends of the common tie rod 63, in the direction X10. Here, this is the case for all the crosspieces 66 of the plate 60.

[0070] Preferably, as visible in Figures 3 and 5, each spar 65 is received in a respective notch 16, belonging to the base plate 11, by crossing said notch 16. Each notch 16 is advantageously formed on an edge, at the perimeter of the base plate 11. Each notch 16 crosses the base plate 11 from one side to the other in the direction X10 and is crossed from one side to the other by the spar 65. On one side of the base plate 11 which is opposite the stack, the anchor 61 comes to bear against the base plate 11 in the opposite direction to the compression direction X10, preferably at the opening of the notch 16.Preferably, the base plate 11 comprises one or more recesses 17, formed on this side of the base plate 11, to receive the anchors 61 in a manner embedded in the base plate 11, to thus limit, or even block, the movements of the anchor 61 relative to the plate in the two transverse directions Y10 and Z10, preferably in both directions of each transverse direction Y10 and Z10. Where appropriate, the notches 16 open into said recesses 17, to allow the anchors 61 to be engaged in the notches 16 in a transverse direction perpendicular to the plane P60.

[0071] Preferably, at least one of the anchors 61, and even each anchor 61, comprises at least one wing 67, or even two wings 67. Here, each anchor 61 comprises two wings 67. Each wing 67 extends transversely with respect to the direction X10, in particular along the plane P60, projecting radially from the spar 65. Here, for each spar 65, the two wings 67 are formed on either side of the spar 65. It can be provided that, for two neighboring anchors 61, the adjacent wings 67, one belonging to one of the two anchors 61 and the other to the other of the two anchors 61, are connected, as is the case on the left in Figure 5, or disjointed, as is the case on the right in Figure 5. It is by means of said wings 67 that the anchor 61 comes to bear against the base plate 11 in the opposite direction to the direction X10. It is advantageously provided that each wing 67 is received in the recess 17.It is by means of the wings 67 that the draw plate 60 is attached to the base plate 11, being retained by the wings, in the opposite direction to the X10 direction. The wings 67 being arranged in the plate plane P60, the attachment of the pull plate 60 to the base plate 11 induces little or no bending stresses on the pull plate 60, except possibly locally at the wings 67. Preferably, the pull plate 60 is not fixed to the base plate 11, but only retained in the opposite direction to the direction X10 by the anchors 61, and positioned transversely relative to the base plate 11, transversely relative to the direction X10, here by receiving the longitudinal members 65 in the notches 16. This makes it possible to limit the stress concentrations at the anchors 61 and to facilitate the mounting of the pull plates 60, since there is no need to fix the plates 60 to the base plate 11.

[0072] Preferably, as visible in Figure 5, each notch 16 is open in a transverse direction relative to the direction X10, here in the direction Y10, over its entire length. Thus laterally open, the notches 16 allow an introduction of each spar 65 into its respective notch 16 by translation of the pulling plate 60 parallel to the direction Y10, relative to the base plate 11, by approaching the pulling plate 60, in its final orientation, until each spar 65 is received in its respective notch 16, with positioning of the anchors 61 against the base plate 11. If the recess 17 is provided, it is also provided that the recess 17 is open laterally, here in the direction Y10, like the notches 16, so that the anchors 61 can be received therein by introduction parallel to the direction Y10.Thanks to these arrangements, the pull plate 60 can be inserted in one piece into all the notches 16 at once, so that the mounting of the plate 60 on the base plate 11 is facilitated and can be carried out in one go, preferably without tools.

[0073] Preferably, each pull plate 60 comprises as many primary anchors 61 as secondary anchors 62, here three of each. Preferably, each plate 60 comprises as many side members 65 as individual tie rods 64, here three of each. Preferably, each plate 60 comprises as many side members 65 as primary anchors 61, here three of each. Preferably, each plate 60 comprises as many individual tie rods 64 as secondary anchors 62, here three of each.

[0074] For each pull plate 60, the individual tie rods 64 are preferably arranged along the plane P60, being distributed over the width of the plate 60. Preferably, each individual tie rod 64 is in the form of a rod, or an elongated element, parallel to the direction X10. This rod extends one of the side members 65, if such a side member 65 is provided for the common tie rod 63, parallel to the direction X10. Each individual tie rod 64 is attached to the common tie rod 63, in particular is attached respectively to one of the side members 65 of the common tie rod 63. This attachment is made at one of the ends of the individual tie rod 64, and at a corresponding end of the side member 65. Preferably, along the direction X10, each tie rod 64 is axially aligned with the primary anchor 62 that it carries and with the primary anchor 61 carried by the side member 65 attached to this individual tie rod 64.In other words, each tie rod 64 is axially aligned, along the compression direction X10 with two of the anchors 61 and 62 of the pull plate 60, being arranged between said two anchors 61 and 62.

[0075] Each tie rod 64 is preferably rigid, in the same way as the side members 65, if they are provided, or as the common tie rod 63. Unlike the side members 65 which are connected to each other by the cross members 66, the tie rods 64 are not connected to each other other than by the flange 40 and by the common tie rod 63 of the pulling plate 60. Preferably, all the tie rods 64 are of the same length.

[0076] Preferably, for each pull plate 60, if not for at least one of them, at least two tie rods 64, namely the tie rods placed at the edges of the pull plate 60, are spaced apart by an inter-tie rod distance L64 which is greater than 50%, or even greater than 70%, of the width L20 of the stack 20. The distances L64 and L65 are advantageously equal or close. The inter-tie rod distance L64 is measured perpendicular to the direction X10, along the plane P60 of the pull plate 60, and parallel to the width L20 of the stack 20.

[0077] In the opposite direction to the X10 direction, each tie rod 64 reaches the flange 40, and preferably crosses it. Preferably, as seen in Figures 3 and 4, each individual tie rod 64 is received in a respective notch 18, each notch 18 being formed in the flange 40, and each individual tie rod 64 passing through said respective notch 18. Each notch 18 is advantageously formed at the end of one of the arms 42, 43, 44, 45, 46 and 47 of the flange. Each notch 18 passes through the flange 40 from one side to the other in the direction X10 and is passed through from one side to the other by the tie rod 64. On one side of the flange 40 which is opposite the stack 20, the anchor 62 bears against the flange 40 in the compression direction X10, in particular against one of the arms 42 to 47, preferably at the opening of the notch 18.Preferably, the flange 40 comprises, for each anchor, a counterbore or a recess, formed on this side of the flange 40, to receive the anchor 62 in a manner embedded in the flange 40. Where appropriate, the notches 18 open into said counterbore or recess.

[0078] Preferably, at least one of the anchors 62, and even each anchor 62, forms a head, such as a screw head, which is fixedly attached to the end of the tie rod 64 which carries this anchor 62. Preferably, the head is made of the same material as the tie rod 64. In this case, it can be provided that a screw forms both the tie rod 64 and the anchor 62 carried by this tie rod 64.

[0079] Advantageously, the anchor 62 is provided to extend in the plane P60, that is to say without being offset from the plane P60 in a direction perpendicular to this plane P60. It is by means of the head that the anchor 62 comes to bear against the flange 40 in the direction X10. It is by means of the head of the anchors 62 that the pulling plate 60 is attached to the flange 40, being retained by the heads, in the direction X10. The anchors 62 being arranged in the plate plane P60, the attachment of the plate 60 to the flange 40 induces little or no bending stress on the plate 60, except possibly locally at the level of the anchors 62. Preferably, the plate 60 is not fixed to the flange 40, but only retained in the direction X10 by the anchors 62, and positioned transversely relative to the flange 40, transversely relative to the direction X10, here by receiving the tie rods 64 in the notches 18.This makes it possible to limit stress concentrations at the anchors 62 and to facilitate the mounting of the plates 60, since there is no need to fix the plates 60 to the flange 40.

[0080] Preferably, each individual tie rod 64 is individually adjustable in position relative to the common tie rod 63 in the direction X10, in that each individual tie rod 64 is connected to the common tie rod 63 by a respective helical connection 68, centered on an axis which is coaxial with the individual tie rod 64 and with the corresponding spar 65. In practice, this helical connection 68 may comprise an external thread, formed at the end of the individual tie rod 64, and an internal thread, formed inside an orifice carried at the end of the spar 65 concerned. The external thread of the tie rod 64 is received inside the orifice of the spar 65 and screwed with the internal thread. Thus, when the tie rod 64 is pivoted about its own axis relative to the tie rod 63, a movement of the tie rod 64 is obtained relative to the tie rod 63, in the direction X10, independently of the other tie rods 64.The anchor 62 being carried by the tie rod 64, adjusting the position of the tie rod along the direction X10 makes it possible to adjust the position of the anchor 62 along the direction X10, relative to the common tie rod 63. Each anchor 62 can therefore be individually adjusted in position to adjust the force F30 applied by the support plate 30, by adjusting the position of the flange 40 using the tie rods 64.

[0081] Preferably, as visible in Figure 3, each notch 18 is open in a transverse direction relative to the direction X10, here in the direction Y10, over its entire length. Thus laterally open, the notches 18 allow an introduction of each tie rod 64 into its respective notch 18 by translation of the pulling plate 60 parallel to the direction Y10, relative to the flange 40, by approaching the plate 60, in its final orientation, until each tie rod 64 is received in its respective notch 18, with positioning of the anchors 62 against the flange 40. If a counterbore or recess is provided on the flange to accommodate the anchor 62, it is also provided that the counterbore or recess is open laterally, here in the direction Y10, like the notches 18, so that the anchors 62 can be received therein by introduction parallel to the direction Y10.Thanks to these arrangements, the plate 60 can be inserted in one piece into all the notches 18 at the same time, so that the mounting of the plate 60 on the flange 40 is facilitated and can be carried out in one go, preferably without tools.

[0082] Thanks to the open notches 16 and 18, the assembly is even simpler in that the pull plate 60 can be attached, in one go, both to the flange 40 and to the base plate 11, by lateral translation of the pull plate 60 in the direction of the flange 40 and the base plate 11, while they are already enclosing the stack 20, via the springs 50 and the support plate 30. Once the plates 60 are mounted, the stack is tightened by adjusting the position of the individual tie rods 64 in the direction X10, here by screwing, to gradually tighten the stack 20 until the desired force F30 is obtained.

[0083] In the example illustrated, the flange 40 is a single flange. Furthermore, it is made in a single piece, a single block, for example a molded metal part. However, the flange 40 could be made in several parts independent of each other. For example, it could be provided that each pair of secondary arms (42, 45), (42, 46) and (44, 47), formed of two secondary arms which extend in opposite directions in the direction Y10, forms a flange part independent of the other parts. In the case of a flange comprising four pairs of two secondary arms which extend in opposite directions in the direction Y10, it is possible to have a flange in two parts independent of each other, each independent part comprising its own main arm, parallel to the direction Z1, and two pairs of secondary arms formed respectively of two secondary arms which extend in opposite directions in the direction Y10 from the main arm of the part concerned.Preferably, each flange part is symmetrical with respect to a median plane perpendicular to the direction Y10. Even in the presence of a flange in several independent parts, the entire flange thus formed is stressed by the two pull plate plates 60 comprising anchors 61, 62 by means of which each pull plate 60 is attached to the base plate 11 and to each of the different parts of the flange 40, the pull plates 60 thus ensuring that the stack 20 is held in compression between the base plate 11 and the support plate 30, in the compression direction X10, by means of the anchors 61, 62, under the action of the springs 50 bearing on the different parts of the flange 40.Preferably, it will be possible to provide, for each independent part of the flange, a second sliding connection, in particular as described above, by means of which said independent part of flange 40 is guided in sliding relative to the support plate 30, in the compression direction X10.

[0084] Any feature described above for one embodiment or variation may be implemented for the other embodiments or variations described above, as far as technically possible.

Claims

CLAIMS Fuel cell, comprising: a base plate (11); a stack (20), which comprises electrochemical cells (21) stacked in a compression direction (X10) and which bears against the base plate (11) in the compression direction (X10); and a compression system, which comprises: • a support plate (30), which is movable relative to the base plate (11) parallel to the compression direction (X10) and which bears against the stack (20) in the compression direction (X10); • springs (50), which bear against the support plate (30) in the compression direction (X10); and • a flange (40), which bears against the springs (50) in the compression direction (X10); characterized in that: the fuel cell comprises a first sliding connection (70), by means of which the support plate (30) is guided in sliding relative to the base plate (11), in the compression direction (X10); and the compression system further comprises pull plates (60), separated from each other, each pull plate (60) comprising anchors (61, 62) by means of which the pull plate (60) is attached to the base plate (11) and to the flange (40), the pull plates (60) thus ensuring that the stack (20) is held in compression between the base plate (11) and the support plate (30), in the compression direction (X10), by means of the anchors (61, 62), under the action of the springs (50) bearing on the flange (40).The fuel cell of claim 1, wherein the first sliding connection (70) comprises a primary slider (71), attached to the support plate (30), and a secondary slider (72), attached to the base plate (11), the primary slider (71) and the secondary slider (72) being received in each other, so as to slide relative to each other in the compression direction (X10), thereby guiding the sliding of the support plate (30) relative to the base plate (11). The fuel cell of claim 2, wherein:. the fuel cell comprises a casing (10), which contains the stack (20) and the compression system and the flange (40) and which is fixedly attached to the base plate (11); and the secondary slider (72) is fixedly attached to the base plate (11) by being fixedly attached to the casing (10), preferably at the height of the flange (40) or the springs (50) along the compression direction (X10). 4.- Fuel cell according to any one of the preceding claims, wherein each pull plate (60) comprises a common tie rod (63) and individual tie rods (64), which carry the anchors (61, 62), each individual tie rod (64) being attached to the common tie rod (63) and having an adjustable position relative to the common tie rod (63) along the compression direction (X10), to adjust the position of the anchors (62) by means of which the pull plate (60) is attached to the flange (40) relative to that of the anchors (61) by means of which the pull plate (60) is attached to the base plate (11). 5.- Fuel cell according to claim 4, in which, so that the respective position of the individual tie rods (64) relative to the common tie rod (63) is adjustable, each individual tie rod (64) is linked to the common tie rod (63) by a helical connection parallel to the compression direction (X10). 6.- Fuel cell according to any one of the preceding claims, in which each pulling plate (60) comprises longitudinal members (65), parallel to the compression direction (X10). 7.- Fuel cell according to claim 6, in which, each draw plate (60) comprises a cross member (66), rigidly connecting the side members (65) to each other by being fixedly connected to said side members (65), the cross member (66) being arranged between the flange (40) and the base plate (11). 8.- Fuel cell according to any one of claims 6 or 7, in which, for each pulling plate (60), at least two longitudinal members (65) are spaced apart by an inter-spar distance (L65) which is greater than 50% of a width (L20) of the stack (20), the inter-spar distance (L65) being measured perpendicular to the compression direction (X10) and the width (L20) of the stack (20) being measured parallel to the inter-spar distance (L65). 9.- Fuel cell according to any one of claims 6 to 8, in which each spar (65) is axially aligned, along the compression direction (X10), with one of the anchors (61, 62) of the pull plate (60), and preferably with two of the anchors (61, 62) of the pull plate (60), being arranged between said two anchors (61, 62). Fuel cell according to any one of claims 6 to 9, wherein at least one of the anchors (61) comprises at least one wing (67), which extends radially from said spar (65) and which bears against the base plate (11) in the opposite direction to the compression direction (X10), for attaching the pull plate (60) to the base plate (11), said at least one wing (67) being arranged in a plate plane (P60) along which the spars (65) extend. A fuel cell according to any preceding claim, wherein for each pull plate (60) the anchors (61, 62) comprise primary anchors (61), via which the pull plate (60) is attached to the base plate (11), and secondary anchors (62), via which the pull plate (60) is attached to the flange (40).Fuel cell according to any one of the preceding claims, wherein the pull plates (60) comprise a first pull plate (60) and a second pull plate (60), which are parallel to each other. Fuel cell according to claim 12, wherein the first pull plate (60) and the second pull plate (60) are arranged on either side of the stack (20), opposite to the stack (20). Fuel cell according to any one of the preceding claims, wherein the fuel cell comprises a second sliding connection (80), by means of which the flange (40) is guided in sliding relative to the support plate (30), in the compression direction (X10). Fuel cell according to any one of the preceding claims, wherein the flange (40) is made of different parts independent of each other.

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