Fuel cell stack with hydrogen fuel cell voltage monitoring interface and vehicle with such a fuel cell stack

Abstract

Vehicle (100) comprising: an electric motor (114); and a fuel cell stack (106) electrically coupled to the electric motor (114), the fuel cell stack (106) comprising: a plurality of bipolar plates (202), each bipolar plate (202) of the plurality of bipolar plates (202) comprising one or more cell voltage measuring tongues (206); and a plurality of insulating under-sealing layers (204) alternating with the plurality of bipolar plates (202); wherein an edge of each cell voltage measuring tongue (206) is shaped to define a hemispherical pocket (504) for mounting a spring-loaded contactor (212) of a measuring device;characterized in that the plurality of bipolar plates (202) comprises a first set of bipolar plates (202) with a first positioning of the cell voltage measuring tongues (206) and a second set of bipolar plates (202) with a second positioning of the cell voltage measuring tongues (206) which is offset with respect to the first positioning of the cell voltage measuring tongues (206); wherein the fuel cell stack (106) further comprises an insulator spacer block (302) having one or more through-holes (308) dimensioned to accommodate the spring-loaded contactor (212) of the measuring device; and wherein each insulating under-sealing layer (204) of the plurality of insulating under-sealing layers (204) comprises a corrugated edge (602).

Description

INTRODUCTION The present invention relates to hydrogen fuel cells and fuel cell voltage monitoring, and in particular to a fuel cell stack according to the preamble of claim 6 and to a vehicle equipped with such a fuel cell stack according to the preamble of claim 1, as is known essentially from JP 2003 - 115 304 A. Essentially comparable fuel cell stacks are described in documents DE 10 2021 121 337 A1 and JP 2009 - 217 939 A. Further prior art is described in documents DE 10 2005 057 091 A1, EP 1 411 569 A2 and DE 102 44 884 A1. Hydrogen fuel cells and related technologies have emerged as a promising clean energy solution, offering high efficiency and zero emissions for various applications ranging from transportation (e.g., private and commercial vehicles, shipping, aircraft, etc.) to stationary power generation. In a hydrogen fuel cell, hydrogen enters through an anode, where it is split into protons and electrons. The protons pass through an electrolyte membrane, while the electrons flow through an external circuit, generating electricity. At the cathode, protons, electrons, and oxygen combine to form water. Hydrogen fuel cells are typically used in fuel cell stacks, which are assemblies of multiple individual hydrogen fuel cells connected in series to increase the overall voltage and output power. With advances in research in this field, understanding and optimizing the performance of fuel cell stacks is becoming a crucial factor for widespread adoption and commercialization. A critical aspect of fuel cell stack operation is the monitoring and control of cell voltages, known as cell voltage monitoring (CVM), as cell voltage directly impacts the overall performance and lifetime of the system. CVM allows researchers and engineers to assess the condition and efficiency of individual cells within a stack.Another important measurement technique is the measurement of hydrogen adsorption / desorption (HAD), as HAD measurements allow a direct measurement of the available surface area for electrochemical reactions that are crucial for fuel cell performance, as well as a diagnostic measurement of the crossover current and short-circuit values ​​of individual cells. SUMMARY According to the invention, a vehicle is presented which is characterized by the features of claim 1. In addition to one or more of the features described in this document, in some embodiments each bipolar plate is formed from the plurality of bipolar plates by joining an anode half-plate and a cathode half-plate. In some embodiments, the edge of each cell voltage measuring tongue is shaped to define the hemispherical pocket by forming the anode half-plate over a first end of a forming tool and forming the cathode half-plate over a second end of the forming tool. In some embodiments, the insulator spacer block includes one or more alignment teeth positioned to align with the respective corrugated edges of the plurality of insulating under-seal layers. In some embodiments, the through-holes are offset to position spring-loaded contact sensors at the first positioning of the cell voltage measuring tongues, and the second positioning of the cell voltage measuring tongues is offset with respect to the first positioning of the cell voltage measuring tongues. Furthermore, according to the invention, a fuel cell stack is presented which is characterized by the features of claim 6. In some embodiments, each bipolar plate is formed from the plurality of bipolar plates by joining an anode half-plate and a cathode half-plate. In some embodiments, the insulator spacer block also includes one or more measuring tongue slots positioned to accommodate one or more corresponding cell voltage measuring tongues of the bipolar plates. In some embodiments, the through-holes are offset to position spring-loaded contact sensors at the first positioning of the cell voltage measuring tongues, and the second positioning of the cell voltage measuring tongues is offset with respect to the first positioning of the cell voltage measuring tongues. In some embodiments, each of the one or more measuring tongue slots comprises one or more channels. In some embodiments, one or more channels are arranged and dimensioned to receive a tip of a spring-loaded contact sensor of the measuring device. Furthermore, a method for forming a plurality of bipolar plates is described. Each bipolar plate comprises one or more cell voltage measuring tongues. A first set of bipolar plates comprises a first positioning of the cell voltage measuring tongues, and a second set of bipolar plates comprises a second positioning of the cell voltage measuring tongues, offset from the first positioning. The method includes forming a plurality of insulating under-sealing layers alternating with the plurality of bipolar plates. The method includes forming an edge of each cell voltage measuring tongue to define a hemispherical pocket for mounting a spring-loaded contact of a measuring device. In some embodiments, each bipolar plate is formed from the plurality of bipolar plates by joining an anode half-plate and a cathode half-plate. In some embodiments, the edge of each cell voltage measuring tongue is shaped to define the hemispherical pocket by forming the anode half-plate over a first end of a forming tool and forming the cathode half-plate over a second end of the forming tool. In some embodiments, an insulator spacer block with one or more alignment holes is positioned to accommodate one or more corresponding alignment tongues of the bipolar plates. In some embodiments, the method includes forming an insulator spacer block having one or more through-holes dimensioned to accommodate the spring-loaded contact transmitter of the measuring device. In some embodiments, each insulating under-seal layer of the plurality of insulating under-seal layers includes a corrugated edge. In some embodiments, the insulator spacer block includes one or more alignment teeth positioned to align with the respective corrugated edges of the plurality of insulating under-seal layers. The aforementioned features and advantages, as well as further features and advantages of the invention, are readily apparent from the following detailed description in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Further features, advantages, and details are included by way of example only in the following detailed description, which refers to the drawings. Fig. 1 is a vehicle configured according to one or more embodiments; Fig. 2A illustrates an example of a portion of a fuel cell stack according to one or more embodiments; Fig. 2B illustrates an exemplary elevation view of the fuel cell stack from Fig. 2A according to one or more embodiments; Fig. 2C illustrates an exemplary detailed elevation view of a section of the fuel cell stack from Fig. 2B according to one or more embodiments; Fig. 3A illustrates an exemplary view of the bipolar plates from Fig. 2A before the installation of an insulator spacer block according to one or more embodiments; Fig. 3B illustrates an exemplary view of the bipolar plates from Fig.3A after installation of the insulator spacer block according to one or more embodiments; Fig. 3C illustrates an exemplary view of the bipolar plates along line AA from Fig. 3B according to one or more embodiments; Fig. 3D illustrates an exemplary view of the bipolar plates along line BB from Fig. 3B according to one or more embodiments; Fig. 4A illustrates an exemplary schematic view of an insulator spacer block according to one or more embodiments; Fig. 4B illustrates an exemplary rear view of the insulator spacer block from Fig. 4A; Fig. 4C illustrates an exemplary front view of the insulator spacer block from Fig. 4A; Fig. 4D illustrates an exemplary side view of the insulator spacer block from Fig. 4A; Fig.Fig. 5A illustrates an exemplary view of a spring-loaded contactor being pressed against an edge of a cell voltage sensing tongue according to one or more embodiments; Fig. 5B illustrates an exemplary view of a pocket of a cell voltage sensing tongue according to one or more embodiments; Figs. 5C and 5D illustrate exemplary views of a pocket of a cell voltage sensing tongue during interface formation with a spring-loaded contactor according to one or more embodiments; Fig. 6A illustrates an exemplary view of bipolar plates after the formation of pockets according to one or more embodiments; Fig. 6B illustrates an exemplary view of bipolar plates after the formation of pockets according to one or more embodiments; Fig.Figure 6C illustrates an exemplary view of bipolar plates during a hydrogen adsorption / desorption (HAD) measurement procedure according to one or more embodiments; Figure 7A illustrates an exemplary view of a fuel cell stack during a cell voltage monitoring (CVM) measurement procedure according to one or more embodiments; Figure 7B illustrates an exemplary view of a fuel cell stack during an HAD measurement according to one or more embodiments; Figure 7C illustrates an exemplary view of a fuel cell stack during a CVM measurement according to one or more embodiments; Figure 8 is a computer system according to one or more embodiments; and Figure 9 is a flowchart according to one or more embodiments. DETAILED DESCRIPTION The following description is for illustrative purposes only. It is understood that in the drawings, corresponding reference symbols denote identical or equivalent parts and features. Understanding and optimizing the performance of fuel cell stacks is crucial for the widespread adoption and commercialization of hydrogen fuel cell technologies. Two of the most important techniques for evaluating fuel cell quality and performance are cell voltage monitoring (CVM) and hydrogen adsorption / desorption (HAD) measurement. CVM allows researchers and engineers to assess the condition and efficiency of individual cells within a hydrogen fuel cell stack, while HAD measurements are used to evaluate hydrogen storage capacity and the surface properties of fuel cell materials. Bipolar plates (BPPs) play a crucial role in fuel cell stacks, fulfilling multiple functions such as distributing reaction gases, removing reaction products, conducting electrical current between cells, and providing mechanical support. BPPs are particularly important in the context of CVM and HAD measurements, as they act as electrically conductive interfaces between adjacent cells during CVM, enabling voltage measurements across individual cells. This allows researchers to identify underperforming cells, detect potential problems like membrane degradation or catalyst poisoning, and optimize stack performance. The conductive nature of the BPPs ensures accurate voltage measurements while maintaining electrical connections throughout the stack.In HAD measurements, including modified hydrogen adsorption / desorption (MHAD) techniques, BPPs play a crucial role in gas distribution and current sensing. HAD and MHAD measurements are used to evaluate the electrochemically active surface area (ECSA) of catalyst layers, a key parameter for assessing fuel cell performance. The flow field designs integrated into BPPs ensure uniform gas distribution in the active area, thus enabling accurate HAD and MHAD measurements. In short, the integration of bipolar plates (BPPs) into fuel cell stacks is fundamental for performing accurate and reliable measurements of cell voltage and hydrogen adsorption / desorption. As research in hydrogen fuel cell technology progresses, optimizing the BPP design remains a crucial factor in improving the overall performance and durability of the stacks. Unfortunately, current BPP designs are quite limited. One of the current challenges in fuel cell stack design, and particularly in BPP design, is improving electrical coupling with the CVM and HAD tap points.For example, ensuring the alignment of pogo pins and / or pogo pin boards at CVM / HAD contact points in the stacking direction (with and without cell repetition tolerances) is challenging, partly due to alignment issues originating from upstream leaf-shaped tongue / insulator designs. A related challenge lies in addressing stacking configurations with uneven board / plate distribution (e.g., the spacing between individual boards in a fuel cell stack may not be consistent across the entire stack). Packaging presents a further challenge, as sufficiently high CVM / HAD contact points can lead to mutual interference between stacked BPP packages.In short, special packaging and / or separators may be required for shipping BPP to avoid CVM / HAD damage, as the BPP contact points can be higher than the height of the uncompressed metal bead gasket (e.g., in an example configuration, the socket features may be ~1.8 mm, while the height of the uncompressed metal bead gasket may be ~1.3 mm). Even disregarding the contact point issues, the small cell repeat or plate spacing (e.g., 0.9 to 1.2 mm) between cells, combined with the limited space available for electrical contact (e.g., 2 mm diameter for commercially available pogo pins), presents a packaging challenge for the application. This invention provides a hydrogen fuel cell voltage monitoring interface that uses spring-loaded contacts. Instead of relying on a conventional contact in the form of a measuring blade (also known as a crimp clamp) that measures the cell voltage across the top surface of the alternating blade / spacer tongues, an insulating spacer is provided that guides spring-loaded contacts directly against the flat edge of the measuring tongues of a fuel cell bipolar plate to perform CVM and / or HAD measurements. Advantageously, the insulating spacer block electrically isolates the tongues from electrical creep and spacing problems and prevents the relatively thin plate tongues from deflecting under a force applied perpendicular to the plate edges.In some embodiments, the bipolar plates described in this document are modified to include hemispherical contact pockets in order to maximize the contact area with spring-loaded ball-end contact (pogo-pin) geometries. In particular, UEA (unitized electrode assembly) underseals can be positioned to overlap the BPP edges, thereby creating a corrugated edge when the BPP contents pockets are pressed against the underseal surface at the repeating spacing of the stacked cells during assembly. One of the advantages of such a design is that the corrugation effect, created by the displacement of a semi-rigid, flat plate, provides additional strength along the corrugation axis.Another advantage of this design is that the repeatable height of the stacked BPP bushings is inherently less prone to contact displacement due to BPP material warping. In short, this configuration results in a self-correcting and more repeatable positioning of the BPP contact areas for interface formation with components or tool engagement, as stacked bushing heights with interposed underseals limit the permissible displacement. Further advantages are achieved, which will be discussed in more detail below. A vehicle according to an exemplary embodiment is generally designated 100 in Fig. 1. The vehicle 100 is shown in the form of an automobile with a body 102. The body 102 comprises a passenger compartment 104 in which a steering wheel, front seats, and rear seats (not shown separately) are arranged. A number of components are arranged in the body 102, including, for example, a fuel cell stack 106, a hydrogen tank 108, an air intake manifold 110, a battery 112, and an electric motor 114 configured to use electrical energy to provide an output torque to an output component 116 (each shown by projection near the front hood). The fuel cell stack 106 receives a flow of hydrogen or other fuel gas from the hydrogen tank 108 and a flow of air, including oxygen gas, from the air intake manifold 110.The fuel cell stack 106 may include an air compressor device (not specified separately) for pressurizing the air to the required pressure. The fuel cell stack 106 may directly supply electrical energy to the electric motor 114 and / or supply electrical energy to the battery 112, which can be stored and used later. The output component 116 may provide the output torque, which is used, for example, to provide propulsion for the vehicle 100. The fuel cell stack 106, the hydrogen tank 108, the air intake manifold 110, the battery 112, and the electric motor 114 are shown only for simplified illustration and discussion. It is understood that the configuration, location, size, arrangement, etc., of these components are not intended to be particularly restricted.Although the present invention is primarily discussed in connection with a fuel cell stack 106 configured for the vehicle 100, the aspects described herein can be similarly integrated into any system (vehicle, building, or other) with a hydrogen fuel cell-based power and / or energy storage system(s). As explained in more detail below, the fuel cell stack 106 comprises bipolar plates designed to be connected to an insulating spacer block configured to guide spring-loaded contacts directly against the flat edge of the measuring tongues of the respective bipolar plates for the purpose of CVM and / or HAD measurements. Fig. 2A illustrates an example of part of a fuel cell stack 106 according to one or more embodiments. The number of individual fuel cells (not shown separately) and their configuration in the fuel cell stack 106 are not to be considered particularly limited, and any number of fuel cells can be combined in the fuel cell stack 106 to produce a desired power output. For example, a fuel cell stack 106 for a vehicle (e.g., the vehicle 100 from Fig. 1) can have two hundred or more stacked fuel cells. The fuel cell stack 106 receives a cathode inlet gas, typically an airflow, which is forced through the fuel cell stack 106 by a compressor (see the discussion of Fig. 1).Not all oxygen is consumed by the fuel cell stack 106, and some of the air can be released as cathode exhaust, which may include water as a byproduct of the stack. The fuel cell stack 106 also receives an anode hydrogen inlet gas, which flows into the anode side of the fuel cell stack 106. In each fuel cell of the fuel cell stack 106, the anode and cathode typically comprise finely dispersed catalytic particles, for example, platinum (Pt), supported on carbon particles and mixed with an ionomer. The catalytic mixture is deposited onto opposite sides of a membrane. The combination of the anode catalyst mixture, the cathode catalyst mixture, and the membrane forms a membrane electrode assembly (MEA) for the respective fuel cell. As shown in Fig. 2A, the fuel cell stack 106 comprises an array of bipolar plates 202. In some embodiments, each cell in the fuel cell stack 106 is defined by a pair of bipolar plates 202 (an anode-side bipolar plate and a cathode-side bipolar plate) between which a MEA (not specified) is arranged. In some embodiments, the bipolar plates 202 and the MEA are positioned between two end plates (not specified). In some embodiments, each fuel cell is flanked by two bipolar plates 202, one on the anode side and one on the cathode side, and the bipolar plates 202 conduct electricity between the adjacent cells of the fuel cell stack 106, thereby enabling the fuel cell stack 106 to generate higher voltages.In some embodiments, the bipolar plates 202 serve as both separating and connecting elements, without this constituting any particular limitation. The bipolar plates 202 separate the anode of one cell from the cathode of the adjacent cell, thus preventing the mixing of the reaction gases (hydrogen and oxygen). In this configuration, the bipolar plates 202 conduct the electric current from one cell to the next, thus enabling the series connection of cells to achieve a desired voltage and / or power. In some embodiments, the bipolar plates 202 include flow channels that distribute the hydrogen to the anode and the oxygen to the cathode evenly across the active surface of each cell, thereby ensuring efficient electrochemical reactions.The bipolar plates 202 also assist in managing the heat generated during fuel cell operation and can ensure the structural integrity and mechanical support of the fuel cell stack 106 (e.g., by ensuring that the cells are properly compressed and aligned). In some embodiments, the bipolar plates 202 are made of a composite material such as graphite, with two plate halves being formed separately and then bonded together, providing anode flow channels on one side of one plate half and cathode flow channels on the opposite side of the other plate half, with optional coolant flow channels provided between the plate halves.In some embodiments, two separate plate halves are stamped and then welded together, so that anode flow channels are provided on one side of one of the plate halves and cathode flow channels are provided on the opposite side of the other plate half, with coolant flow channels being provided between the plate halves. As further shown in Fig. 2A, the fuel cell stack 106 in some embodiments comprises insulating under-seal layers 204 (also referred to as UEA under-seals). In some embodiments, the insulating under-seal layers 204 are used to seal the edges of the MEA to prevent gas leaks and to provide electrical insulation between adjacent bipolar plates 202. The insulating under-seal layers 204 can be made of a variety of suitable semi-rigid polymers and / or plastic films, such as various rubbers (e.g., silicone rubber, fluororubber, etc.) and elastomers (e.g., polyolefin elastomers, fluoroelastomers, etc.). In some embodiments, the bipolar plates 202 include cell voltage measuring tongues 206. Cell voltage measuring tongues 206 are conductive projections and / or contact points arranged on (or integrated into) the bipolar plates 202 within the fuel cell stack 106 to provide access points for measuring the voltage of each individual cell in the fuel cell stack 106. In some embodiments, the cell voltage measuring tongues 206 are designed to provide electrical contact to the active components (not specified separately) of each cell. As further shown in Fig. 2A, in some embodiments the bipolar plates 202 comprise two alternating configurations for the cell voltage measuring probes 206. The bipolar plates 202 can, in particular, comprise plates 208 of type A alternating with plates 210 of type B. In some embodiments, the positioning of the cell voltage measuring probes 206 in the plates 208 of type A is offset from the positioning of the cell voltage measuring probes 206 in the plates 210 of type B in order to meet the requirements for the electrical creepage and clearance (arc). It should be noted that in this configuration the bipolar plates 202 and the cell voltage measuring probes 206 are positioned such that several spring-loaded contactors 212 can be axially applied to the respective edges 214 of the cell voltage measuring probes 206 by a force exerted by the spring-loaded contactors. Fig. 2B illustrates an exemplary elevation view of the fuel cell stack 106 from Fig. 2A according to one or more embodiments. Fig. 2C illustrates an exemplary detailed elevation view of a section 216 of the fuel cell stack 106 from Fig. 2B according to one or more embodiments. As shown in Fig. 2B and Fig. 2C, an electrical contact point 218 is established between the edge 214 of a cell voltage measuring tongue 206 and a tip section 220 of the spring-loaded contactor 212. Fig. 3A illustrates an exemplary view of the bipolar plates 202 (e.g., the bipolar plates 202 from Fig. 2A) before the installation of an insulator spacer block 302 according to one or more embodiments. The insulator spacer block 302 is discussed in more detail with reference to Figs. 4A-4D. Fig. 3B illustrates an exemplary view of the bipolar plates 202 from Fig. 3A after the installation of the insulator spacer block 302 according to one or more embodiments. Fig. 3C illustrates an exemplary view of the bipolar plates 202 along line CC from Fig. 3B according to one or more embodiments. Fig. 3D illustrates an exemplary view of the bipolar plates 202 along line DD from Fig. 3B according to one or more embodiments. As shown in Fig. 3A-3D, the insulator spacer block 302 can include one or more alignment openings (or slots) 304 positioned to fit over and / or otherwise accommodate one or more corresponding alignment tongues 306 (also called retention features or metal retention features) of the bipolar plates 202. The number of alignment openings 304 need not be particularly limited. For example, as shown, 12 alignment openings 304 are arranged in two rows of 6 holes each (6 along the top of the insulator spacer block 302 and 6 along the bottom of the insulator spacer block 302). Other configurations (e.g., with a different number of alignment openings 304) are possible. In some embodiments, the insulator spacer block 302 may include one or more measuring tongue slots 402 (see Fig. 4B) which are positioned to fit over one or more corresponding cell voltage measuring tongues 206 of the bipolar plates 202 and / or otherwise accommodate them. In some embodiments, the insulator spacer block 302 may include one or more through-holes 308 dimensioned to accommodate the respective spring-loaded contact sensors 212. The number of through-holes 308 need not be particularly limited. In some embodiments, the through-holes 308 are arranged such that the spring-loaded contact sensors 212 are positioned at the cell voltage measuring tabs 206 of the alternating plates 208 of type A and plates 210 of type B (see Fig. 3C and Fig. 3D). In other words, in some embodiments, some of the through-holes 308 may be offset from other through-holes 308 in the same manner as the cell voltage measuring tabs 206 of alternating plates 208 of type A and plates 210 of type B may be offset from each other.For example, as shown, 24 through-holes 308 are arranged in four rows of six through-holes 308 each, with one pair of rows (a total of 12 through-holes) positioned for the cell voltage measuring probes 206 of plates 208 of type A and another pair of rows (a total of 12 through-holes) positioned for the cell voltage measuring probes 206 of plates 210 of type B. Other configurations (different number of through-holes 308, different number of rows, etc.) are possible. In some embodiments, the insulator spacer block 302 is configured to form an interface with a tool board 310 (e.g., a printed circuit board) having one or more through-holes 312 dimensioned and positioned to receive the respective spring-loaded contact probes 212 from the plurality of and aligned with the one or more through-holes 308 of the insulator spacer block 302, thereby allowing the spring-loaded contact probes 212 to be inserted through the tool board 310 and through the underlying insulator spacer block 302 to contact the cell voltage measuring tongues 206. In some embodiments, the insulator spacer block 302 includes one or more alignment holes 314 and the tool board 310 includes one or more alignment holes 316 to assist in the alignment of the respective components during installation. Referring to Fig. 3C and Fig. 3D, the insulator spacer block 302 and the tool plate 310, after installation, serve to guide the spring-loaded contact points 212 to the edges 214 of the cell voltage measuring tongues 206 of the bipolar plates 202. It should be noted that the bipolar plate 202 in Fig. 3C is a plate 208 of type A, and the bipolar plate 202 in Fig. 3D is a plate 210 of type B, and that the positioning of the cell voltage measuring tongue 206 in the plate 208 of type A is offset from the positioning of the cell voltage measuring tongue 206 in the plate 210 of type B. In this configuration, the insulator spacer block 302 and the tool plate 310 work together to establish any number of edge contacts (i.e.,to repeatedly position the edges 214 of the cell voltage measuring tongues 206 to a corresponding number of spring-loaded contact transmitters 212 in order to electrically isolate the cell voltage measuring tongues 206 from electrical creep and spacing problems and to prevent the cell voltage measuring tongues 206 from bending when a force is applied perpendicular to the edges 214 during a measurement process. Fig. 4A shows an exemplary schematic view of an insulator spacing block 302 (e.g., the insulator spacing block 302 from Figs. 3A-3D) according to one or more embodiments. Fig. 4B illustrates an exemplary rear view of the insulator spacing block 302 from Fig. 4A. Fig. 4C illustrates an exemplary front view of the insulator spacing block 302 from Fig. 4A. Fig. 4D illustrates an exemplary side view of the insulator spacing block 302 from Fig. 4A. As shown in Figs. 4A-4D, the insulator spacer block 302 can comprise a plurality of through holes 308, a plurality of alignment holes 314, a plurality of alignment openings 304, and a plurality of measuring tongue slots 402. In some embodiments, the measuring tongue slots 402 are positioned to fit over one or more corresponding cell voltage measuring tongues 206 of the bipolar plates 202 and / or otherwise accommodate them (see Fig. 3A). As shown in Fig. 4B, in some embodiments the measuring tongue slots 402 are dimensioned such that a cell voltage measuring tongue 206 inserted into the respective measuring tongue slot 402 can come into contact with two (as shown) or more (not shown separately) of the spring-loaded contactors 212 (see Fig. 3B). In some embodiments, each of the measuring tongue slots 402 includes one or more (as shown in Fig. 4B, two) channels 404. In some embodiments, each of the channels 404 is arranged and dimensioned to receive a tip 220 from one of the spring-loaded contactors 212 (see Fig. 2C). In this way, each of the channels 404 enables a pair of spring-loaded contactors 212 to make contact with the edge 214 of the bipolar plates 202. In some embodiments, the insulator spacer block 302 may include end sections 406 that encompass the alignment openings 304 and extend toward the corresponding alignment tongues 306 of the bipolar plates 202 (see Fig. 3A, Fig. 3C and Fig. 3D). In some embodiments, the end sections 406 partially define a recessed pocket feature 408 that can be used for CVM and / or HAD positioning and alignment. Fig. 5A illustrates an exemplary view of a spring-loaded contactor 212 being pressed against an edge 214 of a cell voltage measuring tongue 206, according to one or more embodiments. In Fig. 5A, it can be seen that a contact interface 502 between the spring-loaded contactor 212 and the edge 214 is inherently limited by a thickness D of the edge 214. The thickness D is not particularly restricted but can be less than 3 millimeters (e.g., 0.05 to 3 millimeters, 1 millimeter, etc.). This results in a relatively small contact area for the spring-loaded contactor 212. To achieve this, in some embodiments the edge 214 is shaped to form a pocket 504 (also referred to as a hemispherical CVM / HAD pocket). Fig. 5B illustrates an exemplary view of a pocket 504 of a cell voltage measuring tongue 206 according to one or more embodiments. In some embodiments, the pocket 504 is a hemispherical pocket. As already discussed, in some embodiments a bipolar plate 202 can be formed by joining two half-plates 506 and 508 (e.g., by joining an anode half-plate with a cathode half-plate). In some embodiments, the pocket 504 is formed during the joining of the two half-plates 506 and 508. In some embodiments, for example, a forming tool (not shown separately) can be placed between the half-plates 506 and 508, the shape and position of which corresponds to the desired pocket 504. In this way, the pocket 504 can be formed when the two half-plates 506 and 508 are pressed together. Figures 5C and 5D illustrate exemplary views of a pocket 504 of a cell voltage measuring tongue 206 during interface formation with a spring-loaded contactor 212 according to one or more embodiments. As shown in Figures 5C and 5D, the contact interface 502 provided by the pocket 504 is enlarged compared to the contact interface 502 shown in Figure 5A. In this way, the pocket 504 increases the electrical conductivity and is more robust against tooling tolerances, since the components are self-aligning and the contact interface 502 is restricted by limiting the degrees of freedom in the position between the cell voltage measuring tongue 206 and the spring-loaded contactor 212. Fig. 6A illustrates an exemplary view of the bipolar plates 202 (e.g., the bipolar plates 202 from Fig. 2A) after the formation of pockets 504 according to one or more embodiments. In some embodiments, the pockets 504 comprise a first plurality of pockets 504a and a second plurality of pockets 504b. In some embodiments, the first plurality of pockets 504a is aligned with the cell voltage measuring tabs 206 of the plates 208 of type A. In some embodiments, the second plurality of pockets 504b is aligned with the cell voltage measuring tabs 206 of the plates 210 of type B. As further shown in Fig. 6A, the type A plates 208 and the type B plates 210 are stacked on top of each other with an insulating underlay 204 sandwiched between them. In some embodiments, the type A plates 208, the type B plates 210, and the insulating underlay 204 are pressed together during the manufacturing process. Fig. 6A shows that the insulating underlay 204 overlaps the pockets 504 and therefore assumes a corrugated edge 602 during manufacturing when the pockets 504 are pressed into the insulating underlay 204. In some embodiments, the insulating underlay 204 is provided in a free state as a flat sheet, which is forced into a corrugated shape (assuming the corrugated edge 602) by the alternating arrangement of the pockets 504.Furthermore, the insulating under-seal layer 204 overlaps the outer plate edges 604 of the bipolar plates 202, thus forming a pocket 606. Although the exact contour of the corrugated edge 602 need not be particularly constrained, in some embodiments the pockets 504 are recessed relative to the pocket 606 for electrical insulation and to attenuate leakage current. In some embodiments, the pockets 504 are positioned to have a so-called 2-fold repetition height from cell to cell, such that the corrugated edge 602 assumes a sinusoidal waviness. This type of configuration allows for better visual identification of the recessed bushing positions of the pockets 504 and greater robustness against folding of the under-seal or covering of the bipolar plates 202 along the bushing axis. Although both pockets 504 (BPP bushings) and pocket 606 (sinusoidal under-seal pocket) are shown in Fig. 6A and Fig.6B, where features are shown recessed by a continuous edge (not shown separately) of the bipolar plates 202 or the insulating under-sealing layer 204, these features can alternatively be applied linearly and not recessed by existing edges (although the bipolar plates 202 and the insulating under-sealing layers 204 must still have some degree of overlap and / or offset for electrical insulation). Fig. 6B illustrates an exemplary view of bipolar plates 202 (e.g., the bipolar plates 202 from Fig. 2A) after the formation of pockets 504 according to one or more embodiments. As shown, the pockets 504 are arranged in alternating rows of four pockets 504 (pockets A1, A2, A3, and A4 alternating with pockets B1, B2, B3, and B4), although the exact number of pockets 504 is only illustrative and is not to be considered particularly limited. In some embodiments, the insulating under-seal layers 204 comprise a plurality of insulating under-seal layers 204a, 204b, 204c, 204d, and 204e configured and arranged as shown. In particular, in some embodiments the insulating under-seal layers 204a, 204b, 204c, 204d and 204e are configured such that two layers 608 of the under-seal insulating material are placed between respective pockets 504 with the same orientation (e.g.between pockets A1 and A2, between pockets B3 and B4, etc.) are arranged. This configuration reduces the probability of a short circuit between the bipolar plates 202 (e.g., edge contact). It can be seen that the plurality of insulating under-sealing layers 204a, 204b, 204c, 204d, and 204e also define a pocket 606 relative to the outer plate edges 604 (see Fig. 6A). An advantage of the embodiment shown in Fig. 6B is the self-correcting positioning of the pockets 504 and the insulating under-seal layers 204. It can be seen, for example, that the height H of the pockets 504 with two layers 608 of the under-seal insulating material inherently limits the amount of permissible displacement between these components, since each pocket 504 exerts a resisting force 610 on the pockets 504 both above and below it (i.e., the pockets 504 resist buckling). The result of this configuration is that any pockets 504 that were initially misaligned are forced back into alignment by the adjacent pockets 504.This makes the configuration less susceptible to contact deviations, for example due to bent BPP material, and allows for a more predictable and repeatable positioning of the BPP contact areas for interface formation with components or the engagement of tools (e.g. for CVM and / or HAD measurements). Fig. 6C illustrates an exemplary view of bipolar plates 202 (e.g., the bipolar plates 202 from Fig. 2A) during a HAD measurement operation according to one or more embodiments. Fig. 6C is provided to show how the pocket 606, defined by the multiple insulating under-sealing layers 204a, 204b, 204c, 204d, and 204e (see Fig. 6B), can be used for alignment of spring-loaded contactor boards (e.g., the insulator spacer block 302 and the tool board 310 from Fig. 3A and Fig. 3B). For example, it can be seen that the stacked insulating under-seal layers 204a, 204b, 204c, 204d and 204e provide a flat stack of edges 612, resulting in a recessed pocket feature (e.g. the pocket 606) that can be used for CVM and / or HAD positioning and alignment. Fig. 7A illustrates an exemplary view of a fuel cell stack 106 (see Fig. 2A) during a CVM measurement procedure according to one or more embodiments. As shown in Fig. 7A, a CVM module 702 is installed over the pockets 504 of the cell voltage measuring tongues 206. The CVM module 702 may, for example, comprise an insulator spacer block 302 and a tooling board 310 (see Fig. 3B). In the configuration shown in Fig. 7A, the CVM module 702 positions the spring-loaded contactors 212 in a staggered skip pattern, placing one spring-loaded contactor 212 on each bipolar plate 202 of the fuel cell stack 106 (note that CVM measurements require only one contact per BPP). It can be seen that some of the pockets 504 are skipped pockets 704, meaning that only a portion of the pockets 504 are used pockets 706. This staggered configuration increases the space for the components to be connected (e.g., by a factor of 2 compared to conventional straight-line configurations). Furthermore, the alternating footprints between plates 208 of type A and plates of type B, together with the alternation between a predetermined subgroup (e.g. between two of four, as shown) of the cell voltage measurement tongues 206, result in a 4-fold cell repetition distance for pogo contact points. Fig. 7B illustrates an exemplary view of a fuel cell stack 106 (see Fig. 2A) during a HAD measurement procedure according to one or more embodiments. As shown in Fig. 7B, an HAD module 708 is installed over the pockets 504 of the cell voltage measuring tongues 206. The HAD module 708 may, for example, comprise an insulator spacer block 302 and a tooling board 310 (see Fig. 3B). In the configuration shown in Fig. 8B, the HAD module 708 positions the spring-loaded contact transmitters 212 in a staggered skip pattern that repeats every four pockets 504, thus placing two spring-loaded contact transmitters 212 on each bipolar plate 202 of the fuel cell stack 106 (note that HAD measurements require two contacts per BPP). This configuration offers at least a 4-fold improvement in spacing compared to conventional straight-line configurations.It can be seen that some of the pockets 504 are skipped pockets 704 and some are used pockets 706, in a similar way to the CVM module 702 discussed in Fig. 7A. Fig. 7C illustrates an exemplary view of a fuel cell stack 106 (see Fig. 2A) during a CVM measurement procedure according to one or more embodiments. As shown in Fig. 7C, a CVM module 702 is installed over the pockets 504 of the cell voltage measuring tongues 206. The CVM module 702 can, for example, comprise an insulator spacer block 302 and a tooling board 310 (see Fig. 3B). In the configuration shown in Fig. 7C, the CVM module 702 includes alignment teeth 710 (also referred to as CVM / HAD pogo pin teeth). The alignment teeth 710 can be integrated into any underlying component of the CVM module 702 (e.g., the insulator spacer block 302 and / or the tooling board 310). Although shown for a CVM module 702, a HAD module 708 (see Fig. 7B) can similarly include alignment teeth 710. As can be recalled from Fig. 6A, the insulating under-seal layers 204 overlap the pockets 504 and therefore assume a corrugated edge 602 during manufacturing when the pockets 504 are pressed into the insulating under-seal layers 204. In some embodiments, this configuration results in the insulating under-seal layers 204 terminating at the bipolar plates 202 in an alternating pattern of stacked wide spacings 712 and stacked narrow spacings 714. In some embodiments, the CVM module 702 (or the HAD module 708) is designed such that the alignment teeth 710 are aligned with the wide spacings 712 of the stacked under-seal layers. This configuration provides an intuitive, simple visual and tactile way to confirm the correct positioning of the components of the fuel cell stack 106 (e.g. the insulating under-sealing layers 204, pockets 504, etc.). Fig. 8 illustrates aspects of an embodiment of a computer system 800 that can perform various aspects of the embodiments described in this document. In some embodiments, the computer system(s) 800 can be integrated into and / or otherwise combined with a bipolar plate measurement system, such as a CVM module 702 or a HAD module 708. In some embodiments, the computer system 800 can, for example, apply or receive a signal (e.g., voltage, current, etc.) at one (for CVM measurements) or two (for HAD measurements) spring-loaded contact transmitters 212 and underlying pockets 504. The computer system 800 comprises at least one processing device 802, which generally includes one or more processors or processing units for performing various functions, such as all and / or any functions described with reference to Fig. 9. The components of the computer system 800 also include a system memory 804 and a bus 806, which connects various system components, including the system memory 804, to the processing device 802. The system memory 804 can comprise a variety of media readable by the computer system. These media can be any available media accessible to the processing device 802, including volatile and non-volatile media, as well as removable and non-removable media.System memory 804, for example, includes non-volatile memory 808 such as a hard disk and may also include volatile memory 810 such as random access memory (RAM) and / or cache memory. Computer system 800 may also include other removable / non-removable, volatile / non-volatile computer system storage media. The system memory 804 can comprise at least one program product with a set of program modules (e.g., at least one) configured to perform the functions of the embodiments described in this document. For example, the system memory 804 stores various program modules that generally perform the functions and / or methods of the embodiments described herein. One or more modules 812, 814 may be present for performing functions related to the block diagrams described in this document. The computer system 800 is not limited to this, as other modules may be present depending on the desired functionality of the computer system 800.In the sense used in this document, the term module refers to a processing circuit which may include an application-specific integrated circuit (ASIC), an electronic circuit, a processor (common, dedicated or group) and memory that executes one or more software or firmware programs, a combinational logic circuit and / or other suitable components that provide the described function. The processing device 802 can also be configured to communicate with one or more external devices 816, such as a keyboard, a pointing device, and / or other devices (e.g., a network card, a modem, etc.), which enable the processing device 802 to communicate with one or more other computing devices. Communication with various devices can be made via the input / output (I / O) interfaces 818 and 820. The processing device 802 can also communicate with one or more networks 822, such as a local area network (LAN), a wide area network (WAN), a bus network, and / or a public network (e.g., the Internet), via a network adapter 824. In some embodiments, the network adapter 824 is or includes an optical network adapter for communication over an optical network. It is understood that other hardware and / or software components may also be used in conjunction with the computer system 800, even if not shown. Examples include, but are not limited to, microcode, device drivers, redundant processing units, external hard disk arrays, RAID systems, data archiving systems, etc. Referring to Fig. 9, a flowchart 900 is shown for the use of a hydrogen fuel cell voltage monitoring interface using spring-loaded contacts to monitor a fuel cell stack according to a general embodiment. The flowchart 900 is described with reference to Figs. 1-8 and may include further steps not shown in Fig. 9. Although the blocks shown in Fig. 9 are presented in a specific order, they may be rearranged, subdivided, and / or combined. In Block 902, the method comprises forming a plurality of bipolar plates. In some embodiments, each bipolar plate of the plurality of bipolar plates comprises one or more cell voltage measuring tongues. In some embodiments, the plurality of bipolar plates comprises a first set of bipolar plates with a first positioning of the cell voltage measuring tongues and a second set of bipolar plates with a second positioning of the cell voltage measuring tongues, which is offset with respect to the first positioning of the cell voltage measuring tongues. In Block 904, the process involves forming a multitude of insulating under-sealing layers alternating with the multitude of bipolar plates. In Block 906, the procedure includes forming an edge of each cell voltage measuring tongue to define a hemispherical pocket for mounting a spring-loaded contact sensor of a measuring device. In some embodiments, each bipolar plate is formed from the plurality of bipolar plates by joining an anode half-plate and a cathode half-plate. In some embodiments, the edge of each cell voltage measuring tongue is shaped to define the hemispherical pocket by forming the anode half-plate over a first end of a forming tool and forming the cathode half-plate over a second end of the forming tool. In some embodiments, the method includes forming an insulator spacer block having one or more through-holes dimensioned to accommodate the spring-loaded contact transmitter of the measuring device. In some embodiments, each insulating under-seal layer of the plurality of insulating under-seal layers includes a corrugated edge. In some embodiments, the insulator spacer block includes one or more alignment teeth positioned to align with the respective corrugated edges of the plurality of insulating under-seal layers.

Claims

Vehicle (100) comprising: an electric motor (114); and a fuel cell stack (106) electrically coupled to the electric motor (114), the fuel cell stack (106) comprising: a plurality of bipolar plates (202), each bipolar plate (202) of the plurality of bipolar plates (202) comprising one or more cell voltage measuring tongues (206); and a plurality of insulating under-sealing layers (204) alternating with the plurality of bipolar plates (202); wherein an edge of each cell voltage measuring tongue (206) is shaped to define a hemispherical pocket (504) for mounting a spring-loaded contactor (212) of a measuring device;characterized in that the plurality of bipolar plates (202) comprises a first set of bipolar plates (202) with a first positioning of the cell voltage measuring tongues (206) and a second set of bipolar plates (202) with a second positioning of the cell voltage measuring tongues (206) which is offset with respect to the first positioning of the cell voltage measuring tongues (206); wherein the fuel cell stack (106) further comprises an insulator spacer block (302) having one or more through-holes (308) dimensioned to accommodate the spring-loaded contactor (212) of the measuring device; and wherein each insulating under-sealing layer (204) of the plurality of insulating under-sealing layers (204) comprises a corrugated edge (602). Vehicle (100) according to claim 1, wherein each bipolar plate (202) is formed from the plurality of bipolar plates (202) by connecting an anode half-plate (508) and a cathode half-plate (508). Vehicle (100) according to claim 2, wherein the edge of each cell voltage measuring tongue (206) is shaped to define the hemispherical pocket (504) by forming the anode half-plate (506) over a first end of a forming tool and forming the cathode half-plate (508) over a second end of the forming tool. Vehicle (100) according to claim 1, wherein the through holes (308) are offset to position spring-loaded contact sensors (212) at the first positioning of the cell voltage measuring tongues (206), and the second positioning of the cell voltage measuring tongues (206) is offset with respect to the first positioning of the cell voltage measuring tongues (206). Vehicle (100) according to claim 1, wherein the insulator spacer block (302) comprises one or more alignment teeth (710) which are positioned for alignment on the respective corrugated edges of the plurality of insulating under-sealing layers (204). Fuel cell stack (106), comprising: a plurality of bipolar plates (202), each bipolar plate (202) of the plurality of bipolar plates (202) comprising one or more cell voltage measuring tongues (206), wherein an edge of each cell voltage measuring tongue (206) is shaped to define a hemispherical pocket (504) for mounting a spring-loaded contact sensor (212) of a measuring device; a plurality of insulating under-sealing layers (204) alternating with the plurality of bipolar plates (202); characterized in that the plurality of bipolar plates (202) comprises a first set of bipolar plates (202) with a first positioning of the cell voltage measuring tongues (206) and a second set of bipolar plates (202) with a second positioning of the cell voltage measuring tongues (206) which is offset with respect to the first positioning of the cell voltage measuring tongues (206);wherein the fuel cell stack (106) further comprises an insulator spacer block (302) with one or more alignment holes positioned to receive one or more corresponding alignment tongues of the bipolar plates (202), wherein the insulator spacer block (302) further comprises one or more through-holes (308) dimensioned to receive the spring-loaded contactor (212) of the measuring device; and wherein each insulating under-seal layer (204) of the plurality of insulating under-seal layers (204) comprises a corrugated edge (602). Fuel cell stack (106) according to claim 6, wherein each bipolar plate (202) is formed from the plurality of bipolar plates (202) by connecting an anode half-plate (506) and a cathode half-plate (508). Fuel cell stack (106) according to claim 6, wherein the insulator spacer block (302) comprises one or more measuring tongue slots (402) positioned to accommodate one or more corresponding cell voltage measuring tongues (206) of the bipolar plates (202).

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