Voltage monitoring device for a battery stack, in particular for a fuel cell stack

Abstract

A voltage monitoring device (1) for a battery stack (2) including a plurality of electrical plates (4) sandwiching an insulating layer (6), the voltage monitoring device being configured to monitor the voltage of at least one electrical plate (4) of the battery stack (2), and including at least one voltage monitoring unit (8) having a contact element (22) in contact with at least one electrical plate (4). The voltage monitoring device (1) includes a first signal line (44) configured to supply a first signal from a signal source to a processing unit (46). The voltage monitoring unit (8) includes a first signal path interruption element (42) disposed on the first signal line (44). The first signal path interruption element (42) is connected to the contact element (22) and is configured to transfer the first signal depending on the voltage present in at least one electrical plate (4). The voltage monitoring device (1) includes a support element (20) designed to be disposed within the battery stack. The support element (20) is configured to support at least the contact element (22).

Description

Technical Field

[0001] The present invention relates to a battery stack, in particular to a voltage monitoring arrangement for a fuel cell stack as claimed in claim 1.

Background Art

[0002] Typically, a battery stack is composed of a plurality of stacked electrical plates separated from each other by insulating layers. In the case of a fuel cell stack in particular, the electrical plates are bipolar plates and the insulating layers are membrane electrode assemblies. The bipolar plate itself is a combination of an anode plate and a cathode plate fixed to each other, and adjacent bipolar plates will be separated, or in other words, sandwiched, by the membrane electrode assembly. The cathode and anode plates forming the bipolar plate are usually so-called flow field plates made of conductive metal or graphite plates, having a flow field for reactants on one side and a flow field for a cooling fluid on the opposite side. In the assembled state of the membrane electrode assembly, the flow field plates are arranged on top of each other such that the cooling fluid flow fields face each other and the reactant flow fields face the membrane electrode assembly being sandwiched. The current generated by the membrane electrode assembly during the operation of the fuel cell stack will result in a potential difference between the bipolar plate assemblies.

[0003] During the operation of the battery stack, it is necessary to monitor the voltage generated by the stacked cells to check whether the stack is operating within the intended operating parameters. For this purpose, the electrical plates usually comprise voltage monitoring units which are fixed to the electrical plates and which are provided with wires for connecting the voltage monitoring units to an external voltage monitoring control device which monitors and controls the operation of the stack.

[0004] Therefore, it is known to use a wire as a voltage monitoring unit by soldering or welding the wire directly to an electrical plate. In the field of fuel cell stacks, it is also known to use pin connections, where the pins are inserted between the plates of a bipolar plate and are fixed by frictional force or press-fitting.

[0005] However, placing and fixing wires in a battery stack is cumbersome and time-consuming, making the stacking process inefficient and slow. Furthermore, known fixing methods are prone to causing failures within the stack as wires or pins may become detached from the plates or be placed in incorrect positions. Additionally, due to the normal tight stacking of the insulating layers associated with the electrical plates, there is insufficient space in the battery stack to attach a voltage monitoring unit that would be easy to install.

[0006] Furthermore, the voltage of a battery stack can be monitored by measuring the voltage of each electrical plate and comparing each measured voltage to a reference voltage or a threshold voltage. Alternatively, the voltage within a fuel cell stack can be measured by comparing the voltage of one plate to the voltage of the previous plate and monitoring the difference. In any case, measurement of the voltage of each plate is required, which necessitates corresponding measurement means that are costly. SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] Accordingly, an object of the present invention is to provide a voltage monitoring device that is cost-efficient and can be easily implemented in an efficient and reliable manner by a battery stack, particularly a fuel cell stack. MEANS FOR SOLVING THE PROBLEMS

[0008] This object is solved by a voltage monitoring device for a battery stack according to claim 1.

[0009] The voltage monitoring device is configured to monitor the voltage of at least one electrical plate of a battery stack. Such a battery stack may in particular be a fuel cell stack and may include a plurality of electrical plates separated by an insulating layer.

[0010] In general, it should be noted that in the present application, the term "electrical plate" does not necessarily refer to a rigid electrical plate. Also, a flexible layered electrical element (anode or cathode) may in some cases be referred to as an electrical plate in the present application.

[0011] Furthermore, the battery stack may be a fuel cell stack, in which case the electrical plates are bipolar plates consisting of an anode plate and a cathode plate fixed to each other. In that case, the insulating layer is a membrane electrode assembly. The bipolar plate is typically a rigid metal or graphite plate having a flow field structure for supplying and distributing reactants and / or coolant to the bipolar plate and / or an adjacent membrane electrode assembly.

[0012] The voltage monitoring device includes at least one voltage monitoring unit with a contact element. The contact element is connected to at least one of the plurality of electrical plates, for example in the form of a pin or other type of connector. In a preferred embodiment described below, there is one or more voltage monitoring units, each having a contact element, and each contact element is connected to one of the plurality of electrical plates. Thereby, the contact element is preferably arranged on the surface of a support element such that the contact element is in electrical contact with the electrical plate.

[0013] To monitor the voltage of the battery stack, the voltage monitoring device includes a first signal line configured to supply a first signal from a signal source to a processing unit, and the voltage monitoring unit includes a first signal path interruption element arranged on the first signal line, the first signal path interruption element being connected to the contact element and configured to transfer the first signal depending on the voltage present on the electrical plate.

[0014] Therefore, instead of directly measuring and monitoring the voltage of the electric plate, the voltage monitoring device proposed herein uses an indirect monitoring method. The first signal is transmitted to the processing unit on the first signal line. The first signal itself is applied to the first signal line independently of the voltage of the electric plate. For example, the first signal on the first signal line may be generated from a light source or a power source such as a current source or a voltage source.

[0015] Alternatively, the signal source may be the first electric plate among a plurality of electric plates. This means that the first signal will be generated from the first electric plate and, after being supplied to the first signal line, will function as the first signal on the signal line. Thereafter, the transmission on the first signal line may be interrupted, or the first signal may be transferred using a further voltage monitoring unit and a corresponding signal path interruption element of a further electric plate, as described later.

[0016] However, the transmission of the first signal on the first signal line depends on the voltage of the electric plate, as described later. The voltage of at least one electric plate is taken out by a contact element and transmitted to the first signal path interruption element. Thereafter, the first signal path interruption element will close (i.e., connect) or open (i.e., interrupt) the first signal line depending on the taken-out voltage of at least one electric plate. Alternatively, the first signal path interruption element may open to transfer the signal on the first signal line and close to interrupt the first signal line depending on the taken-out voltage of at least one electric plate. When the first signal path interruption element closes the first signal line, the first signal will be transferred to the processing unit. When the first signal path interruption element opens (i.e., interrupts) the first signal line, the first signal will not be transferred to the processing unit.

[0017] The processing unit can only monitor whether the first signal will be received later. If the processing unit does not receive any signal, it may be interpreted that there is no voltage on at least one electric plate or the voltage is too low, so the electric plate is not operating as intended, that is, not operating within the intended operating parameters. Alternatively, depending on the implementation of the signal path interruption element as described above, even when the processing unit receives a signal, there may be no voltage on at least one electric plate or the voltage may be too low, so this may be interpreted as the electric plate not operating as intended. For example, this may particularly apply when there is a defect in the electric plate. Therefore, the proposed voltage monitoring device provides a method for simply and cost-effectively monitoring the voltage of the electric plate without actually measuring the voltage of the electric plate.

[0018] Alternatively, depending on the implementation of the signal path interruption element as described above, when the processing unit receives a signal, there may be no voltage present on at least one electrical plate, or the voltage may be too low, which may be interpreted as the electrical plate not operating as intended. Thus, the combination of the signal path interruption element and the signal line can transfer the signal on the first signal line when the electrical plate is operating as intended, and not transfer the signal (i.e., interrupt the signal line) when the electrical plate is not operating as intended. Or, conversely, the combination of the signal path interruption element and the signal line can not transfer the signal on the first signal line (i.e., interrupt the signal line) when the electrical plate is operating as intended, and transfer the signal when the electrical plate is not operating as intended. Thus, in the first exemplary implementation, the processing unit can determine that the electrical plate is not operating as intended when it does not receive a signal, and in the second exemplary implementation, the processing unit can determine that the electrical plate is not operating as intended when it receives a signal. It should be noted that both implementations may be equally used below, and that the same features and examples apply to other implementations even if only one possible implementation is described.

[0019] To form a contact between the contact element and the electrical plate, the voltage monitoring device includes a support element. The support element is designed to be disposed within the battery stack and is configured to support at least the contact element. The support element may be shaped, for example, by injection molding. The contact element may be molded with the support element, preferably by injection molding, or may be attached to the support element later.

[0020] The support element may be made of an electrical insulating material, preferably a plastic material, and the contact element may be made of a conductive material. In this regard, metals such as copper, aluminum, silver, gold, tin, etc. are preferred. When determining the specific material of the contact element, the material of the electrical plate must be considered to avoid galvanic problems. For an electrical plate made of stainless steel, a coated copper material such as gold-plated copper, for example, is preferred. Further, the contact element may be an elastic element, and preferably the contact element may be elastically formed. For example, the contact element may be formed as a spring.

[0021] According to a further embodiment, the processing unit is configured to output a warning signal when the first signal is not transferred to the processing unit. As already described above, the processing unit will determine that at least one of the electrical plates is not operating as intended when the processing unit does not receive the first signal. In this case, the processing unit can output a warning signal indicating that at least one electrical plate is not operating as intended. Alternatively, as described above, the processing unit can also output a warning signal when it receives the first signal.

[0022] When the battery stack includes two or more electrical plates according to a further embodiment, the voltage monitoring device includes a plurality of voltage monitoring units, each including a contact element in contact with one of the plurality of electrical plates. Further, each voltage monitoring unit includes a first signal path interruption element disposed on a first signal line, which is connected to the contact element and configured to transfer a first signal depending on the voltage present on each respective electrical plate. The first signal path interruption elements of all the voltage monitoring units are connected in series. Therefore, if one of the electrical plates is not operating as intended, the voltage generated by the non-operating-as-intended electrical plate will fall below the above-mentioned reference threshold voltage, and the corresponding first signal path interruption element will interrupt the first signal line, and the processing unit will not receive the first signal. Conversely, when the voltage generated by each respective electrical plate exceeds the reference threshold voltage, the first signal path interruption element will allow the first signal to pass through. In this case, the processing unit will receive the first signal. As described above, the interruption and transfer of signal transmission can also be reversed, that is, the signal is transferred when the electrical plate is not operating as intended, and the signal is not transferred when the electrical plate is operating as intended.

[0023] Therefore, instead of monitoring the exact voltage of each electric plate, it is sufficient to monitor the voltage of the electric plates in a more abstract way. If one of the electric plates is not operating as intended, since it is necessary to disassemble the completed battery stack, it is sufficient to monitor the voltages of all the electric plates as a whole. If one of the electric plates is not operating as intended, the first signal is not transferred to the processing unit (alternatively, the first signal is transferred as described above), so the processing unit determines that at least one of the electric plates is not operating as intended, that is, although it is not known which electric plate is not operating as intended, the entire stack is not operating as intended. In this case, after disassembling the entire battery stack, each electric plate can be checked for its function. Thus, the voltage monitoring device described herein provides a simple and cost-effective way to monitor a battery stack. Alternatively, an additional evaluation unit can be installed to evaluate each electric plate individually before disassembling the entire battery stack. For example, such an evaluation unit can be attached to each electric plate for further inspection.

[0024] In another embodiment, only a part of the voltage monitoring unit, i.e., a subgroup of the voltage monitoring unit, includes a signal path interruption element. According to this embodiment, some of the voltage monitoring units include only the contact elements for taking out the voltage of the corresponding electric plate. The taken-out voltages of a plurality of consecutive electric plates are transmitted to each one voltage monitoring unit including a signal path interruption element. This voltage monitoring unit switches the signal path interruption element based on the cumulative total voltage of the previous electric plate. Therefore, instead of interrupting the first signal line when the voltage of the corresponding electric plate falls below a defined threshold value, the voltage monitoring unit interrupts the first signal line when the cumulative total voltage of the previous electric plate falls below a predefined threshold value. Alternatively, when the cumulative total voltage of the previous electric plate falls below a predefined threshold value, the voltage monitoring unit can also transfer the signal on the first signal line.

[0025] For example, every fifth voltage monitoring unit includes a signal path interruption element, which will be arranged within the corresponding support element. The first to fourth voltage monitoring units take out the voltage of the corresponding electrical plate and transfer the taken-out voltage to the fifth voltage monitoring unit. The fifth voltage monitoring unit switches the signal path interruption element when the cumulative voltage of the first to fourth and fifth electrical plates falls below or exceeds a predefined threshold as described above.

[0026] According to a further embodiment, the support element has a base plate. If the electrical plate has at least one protruding structure, for example a bead seal or a flow field, protruding from the base of the electrical plate in the direction of the adjacent insulating layer, and furthermore, the height h b of the base plate of the support element シール is designed to be close to, preferably less than, the protruding height h b of the protruding structure on the base of the electrical plate: h シール ≒ h b < h シール . Thereby, the support element can be arranged within the battery stack without requiring additional space. Furthermore, this has the advantage that the height of the base plate of the support element does not affect the sealing properties of the bead seal and enables the support element and thus also the other elements of the voltage monitoring device to be implemented within the battery stack without increasing the size of the battery stack.

[0027] The first signal path interruption element may be arranged inside the battery stack, for example within the support element, or outside the battery stack. As will be described in detail below, the same applies to the first signal line and the processing unit.

[0028] According to one embodiment, the first signal path blocking element is configured to transfer or block the first signal when the voltage present on at least one electrical plate exceeds a reference threshold voltage. Conversely, when the voltage present on at least one electrical plate is below the reference threshold voltage, the first signal path blocking element may be configured to block signal transmission on the first signal line or transfer the signal. The reference threshold voltage is a voltage that is considered to distinguish the normal operating voltage or voltage range of at least one electrical plate from a voltage indicating a defect or performance of at least one electrical plate that is not operating as intended.

[0029] According to a further embodiment, the first signal is an electrical signal and the first signal path blocking element is a relay, an electrical switch, or an electromechanical switch. The electrical signal may be a voltage or current signal that can be received by a processing unit. The first signal path blocking element may be any type of switch-like element that can block signal transmission of the first signal on the first signal line or transfer the first signal. For example, the signal path blocking element may be a relay in the form of a transistor, particularly a bipolar transistor. The relay can be actuated or switched by the voltage present on the electrical plate. For example, when the relay is a transistor, the voltage of the electrical plate is applied to the base of the transistor, and particularly when the voltage of at least one electrical plate exceeds the reference threshold, the transistor will be connected. Thereafter, the first signal is transmitted via the transistor to the first signal line and transferred to the processing unit.

[0030] According to an alternative embodiment, the first signal may be an optical signal, and the signal path interruption element may be an electrical switch or an electromechanical switch (e.g., a piezo element). In this case, the first signal line may be an optical fiber or the like that transmits an optical signal, and the signal path interruption element may be configured to interrupt the propagation of the optical signal on the first signal line. For example, when using a piezo element that is an electromechanical switch actuated by voltage, the piezo element may be affected by the presence or absence of voltage (depending on the actual implementation) and will open and close the optical path.

[0031] According to a further embodiment, the support element is made of an electrically insulating material and comprises a contact element made of a conductive material, which is arranged on the surface of the support element and is configured to contact an electrical plate. Since known pins and wires are extremely small, fixing the voltage monitoring unit to the plate is a very delicate operation. Furthermore, there is a high risk of misplacing the pins, which can lead to damage to the stack elements and ultimately to the failure of the entire stack. By providing a support element made mainly of an electrically insulating material and having conductive elements only in special places, a simpler and more streamlined operation and attachment of the support element including the contact element become possible.

[0032] Furthermore, the support element can also comprise a voltage monitoring unit, in particular a further element that forms part of the first signal path interruption element or the voltage monitoring unit. The voltage monitoring unit may be incorporated into the support element during the manufacture of the support element, for example, it may be molded or attached to the surface of the support element. Furthermore, wires or the like are integrated into the support element to provide contact between the contact element and the first signal path interruption element and / or the first signal line and / or the processing unit.

[0033] To implement the support elements more efficiently, at least one electrical plate on which the support elements are arranged has at least one through-hole, and the support elements are arranged above and / or in the through-hole. This allows the through-hole to provide additional space for accommodating the support elements and / or the voltage monitoring unit.

[0034] According to a further preferred embodiment, the support element has a base plate and a protruding portion, and the protruding portion is recessed from the base plate, so that a step is formed between the base plate and the protruding portion. Thus, the total height H of the support element VM is advantageously designed to be less than the height of the protruding portion of the electrical plate: h < h シール . Such a support element is at least partially completely accommodated within the electrical plate and thus does not require additional space.

[0035] Preferably, the protruding portion of the support element can be accommodated within the through-hole of the electrical plate. This provides a simple operating element that can be efficiently arranged on and within the through-hole of the electrical plate. Furthermore, the protruding portion can be used to accommodate a first signal path interruption element and / or can be used to accommodate a first signal line.

[0036] The height h of the protruding portion of the support element p is more preferably designed to be less than the thickness H of the electrical plate BPP : h p < H BPP . This allows for a support element that is flush with the electrical plate on at least one side. Such a support element is at least partially completely accommodated within the electrical plate and thus does not require additional space.

[0037] According to a further embodiment, the support element is configured to be stacked on a further support element. To electrically connect two stacked support elements, the support element can include pins for electrically connecting to a further support element. Such pins are particularly useful when a first signal line and / or a first signal path interruption element is disposed within the battery stack, for example within the support element, and needs to conduct across the transition between two support elements. Additionally or alternatively, the support element can be configured to accommodate cables and / or transmit light and can particularly include through holes for providing a connection between two support elements.

[0038] According to a further advantageous embodiment, the support element has a recess on the opposite side of the base plate from the protruding portion, and the recess is dimensioned to accommodate the protruding portion of an adjacent support element, so that one support element is configured to be stacked on a further support element. This ensures that, when the support element extends beyond the electrical plate, for example after compression of the stack, the excess portion does not adversely affect the overall dimensions of the stack.

[0039] Conversely, when such a recess is provided, it is also possible to provide a support element, where the height h p of the protruding portion of the support element is designed to be greater than the thickness H BPP of the electrical plate: h p > H BPP and the depth h r of the recess is configured to accommodate a portion of the protruding portion of the support element that extends beyond the electrical plate. This also means that the stacked support elements define a specific orientation of the components of the battery stack, so that the support element can also be used as an alignment mechanism for the stack components.

[0040] According to a further preferred embodiment, the diameter of the base plate is designed to be larger than the diameter of the through-hole such that the surface of the step abuts at least partially against the surface of the electrical plate and the protruding part extends through the through-hole of the electrical plate. Thereby, a secure attachment of the support element onto and into the through-hole of the electrical plate becomes possible.

[0041] If the support element further includes a cover part, more preferably, in that case, the diameter of the cover part is larger than the diameter of the through-hole such that the support element is fixed to the electrical plate. Thereby, connection and fixation of the cover element to both sides of the plate become possible. The cover element can also be realized, for example, as a snap element that extends beyond the edge of the electrical plate after being inserted from the through-hole such that the support element is fixed to the electrical plate.

[0042] Alternatively or additionally, the cover part may be a separate element configured to interact with the protruding part of the support element to fix the support element to the electrical plate. In this regard, it is particularly preferred that the cover element has a recess designed to accommodate the protruding part such that the connection between the cover elements is made by form fit or press fit. For example, the cover element can be pressed and / or clicked onto the protruding part.

[0043] In order to further provide a signal path interruption mechanism and / or an internal alignment mechanism, the cover element can further include a protrusion on the side opposite to the surface facing the electrical plate, thereby enabling interaction with an adjacent support element, in particular, interaction with the recess of an adjacent support element. Furthermore, the cover element can also have an annular shape that interacts with the protruding part in a friction fit manner, such that the protruding part extends through the annular cover element and can be received in the recess of an adjacent support element.

[0044] This ensures that the support element remains securely fixed to the electrical plate even when the electrical plate is not placed in the stack. This further enables pre - mounting of the support element to the electrical plate before lamination.

[0045] Such a cover element can also be used to accommodate a voltage monitoring unit, in particular a first signal path interruption element. In this case, the wire connecting the contact element and the first signal path interruption element may be arranged within the base plate and the protruding part. Further, the protruding part may be provided with pins or the like for providing an electrical connection between the wire and the first signal path interruption element, that is, between the contact element and the first signal path interruption element.

[0046] If the electrical plate has at least one protruding structure, such as a bead seal or a flow field, protruding from the base of the electrical plate in the direction of the adjacent insulating layer, the height h of the cover part of the support element c is also preferably close to, preferably less than, the protruding height h of the protruding structure on the base of the electrical plate (h シール ≈ h c , preferably h シール < h c シール ) is designed. This further enables reliable placement of the support element and other elements of the voltage monitoring device within the battery stack without requiring additional space and without increasing the dimensions of the battery stack. )

[0047] According to a further preferred embodiment, the protruding portion of the support element may have a first part and a second part, in which case, due to the second part being recessed with respect to the first part, a further step is formed between the first and second parts of the protruding portion, and the further step comprises a contact element configured to contact the electric plate. In this way, it is further preferred that both the step between the base plate and the first part and the step between the first and second parts comprise contact elements. This enables electrical connection not only of a single electric plate but also of two electric plates arranged adjacent to each other, and further reduces the time required in the stacking process, and since only a separate support element is required for every three plates, the stacking process is simplified. Such an arrangement is particularly preferred when one signal path interruption element is connected to one or more contact elements, i.e., when it causes the sensed voltage of one or more electric plates, as will be detailed below.

[0048] According to a further preferred embodiment, the contact element is arranged on the surface of the support element. Preferably, the contact element is arranged on the base plate, preferably on the step, and / or on the protruding portion and / or on the cover portion such that the contact element contacts the electric plate.

[0049] According to a further preferred embodiment, the battery stack has at least two, preferably three, stacked electric plates, in which case the height h of the first and second parts p1 ,h p2It is designed such that the contact element arranged in the first step contacts the first electrical plate, and the contact element arranged in a further step between the first and second parts contacts the second electrical plate. Further, the second part may protrude into the opening of the second electrical plate but does not exceed the second electrical plate. Alternatively, the second part may be configured to be received in a recess of an adjacent support element arranged on a third bipolar plate beyond the second electrical plate. This enables the implementation of the support element within the battery stack without increasing the dimensions of the battery stack. Of course, the support element may have a plurality of further steps, and each step is provided with an electrical connector that contacts the respective electrical plate.

[0050] It is further preferred that the electrical plate has first and second through-holes in and / or on which the support element is received, in which case the dimensions and / or shapes of the first and second through-holes are different from each other. This enables, in particular, an advantageous interaction between the stepped support element and the two adjacent electrical plates. It is further advantageous if the dimensions of the first part of the protruding portion conform to the dimensions and / or shape of the first through-hole and the dimensions of the second part of the protruding portion conform to the dimensions and / or shape of the second through-hole. This enables a fail-safe arrangement of the support element and the through-hole / electrical plate.

[0051] It is further preferred that adjacent electrical plates and corresponding first and second through-holes are arranged such that the first through-hole of one electrical plate is aligned with the second through-hole of the adjacent electrical plate. In this regard, it is more preferred if the electrical plate is symmetric with respect to a 180° rotation about the normal of the surface of the electrical plate. When the electrical plate is a bipolar plate, it is preferred that the bipolar plate is symmetric with respect to a 180° rotation about the normal of the surface on the cathode or anode side. Thereby, a 180° rotation of each second electrical plate of the stack results in an alternating automatic arrangement of the first and second through-holes. In addition to the simplification of manufacturing, stacking and alignment, since only a set of electrical plates needs to be fabricated, it is also possible to correct manufacturing tolerances that may lead to stacks of unequal dimensions.

[0052] According to a further embodiment, the voltage monitoring unit further includes a voltage fluctuation leveling element disposed between the contact element and the first signal path interruption element and configured to transmit a voltage from the contact element to the first signal path interruption element when the voltage exceeds a leveling threshold voltage. Such a voltage fluctuation leveling element can be implemented using, for example, a resistor or any type of filtering element capable of equalizing voltage fluctuations. The voltage fluctuation leveling element can be used to eliminate voltage fluctuations, i.e., to level voltage fluctuations. Such fluctuations can cause the first signal path interruption element to switch very frequently between two different stages. For example, even in the absence of degradation of at least one electrical plate, the voltage may vary within a small range with little change due to typical fluctuations. By using such a voltage fluctuation leveling element, it is possible to avoid the first signal path interruption element from switching between two stages regardless of the degradation of at least one electrical plate. Since the unnecessary switching of the first signal path interruption element is reduced by the voltage fluctuation leveling element, the first signal path interruption element may be protected because the voltage fluctuations are filtered and do not affect the signal path interruption element downstream of the voltage fluctuation leveling element. The reduction in the switching of the signal path interruption element may extend the life of the signal path interruption element.

[0053] According to a further embodiment, the voltage monitoring unit, i.e., the combination of the voltage fluctuation leveling element and the signal path interruption element, can be used to define a reference threshold voltage below which the electric plate is considered not to be operating as intended. That is, when at least one electric plate generates a voltage below such a reference threshold voltage, the signal path interruption element can interrupt the signal transmission on the signal line or transfer the signal on the signal line.

[0054] As already mentioned above, further elements of the voltage monitoring device, in particular the voltage monitoring unit, such as the voltage fluctuation smoothing element, can also be arranged within the battery stack. Alternatively, only some elements may be arranged within or on the support element, and some elements may be arranged outside the support element and even outside the battery stack. For example, a voltage monitoring unit including a contact element, a signal path interruption element, and a voltage fluctuation smoothing element may be arranged within or on the support element, while the signal line and the processing unit may be arranged outside the support element and even outside the battery stack. Furthermore, the signal line may also be arranged within or on the support element and may in particular be guided through the support element.

[0055] According to a further embodiment, two support elements that support contact elements in contact with two adjacent electric plates are arranged at different ends of the battery stack. This has the advantage that there is no need to stack the support elements, so that more space can be used by each support element.

[0056] According to a further embodiment, the voltage monitoring device includes a second signal line connected in parallel with the first signal line. In this embodiment, the voltage monitoring unit includes a second signal path interruption element disposed on the second signal line and connected in parallel with the first signal path interruption element. Since the first and second signal path interruption elements can adapt to different threshold voltages, more detailed monitoring of the electric plate is realized. The first and second signal lines may be disposed within the battery stack, preferably led into a support element, or may be disposed outside the battery stack. Also, one signal line may be disposed within the battery stack and the other may be disposed outside the battery stack.

[0057] For example, the first signal path interruption element may be configured to transfer (or interrupt) the first signal when the voltage of the electric plate exceeds a first reference voltage, and the second signal path interruption element may be configured to transfer (or interrupt) the second signal when the voltage of the electric plate exceeds a second reference voltage. Preferably, the first reference voltage and the second reference voltage are different from each other. This has the advantage that different warning stages can be implemented. For example, since the first signal path interruption element functions as a first warning stage, when the voltage generated by the electric plate falls below a higher reference threshold voltage, the first signal path interruption element interrupts the transmission of the first signal. This higher reference threshold voltage indicates that the battery stack is still functioning but approaching a critical state. When the generated voltage further falls below the lower reference threshold voltage of the second signal path interruption element, the processing unit can determine that it is necessary to disassemble the battery stack and replace at least one of the electric plates.

[0058] The voltage monitoring device may be expandable as needed, for example, by a third signal line and a third signal path interruption element, a fourth signal line and a fourth signal path interruption element, etc. The more signal lines and corresponding signal path interruption elements are used, the more different warning stages can be implemented.

[0059] In this embodiment, when multiple voltage monitoring units are used, it should be noted that the first signal path cutoff elements of all the voltage monitoring units are connected in series, the second signal path cutoff elements of all the voltage monitoring units are also connected in series, and the same applies to the others.

[0060] Further preferred embodiments are defined not only in the description and drawings but also in the dependent claims. In this regard, elements described or illustrated in combination with other elements may exist alone or in combination with other elements without departing from the scope of protection.

[0061] Hereinafter, preferred embodiments of the present invention will be described in relation to the drawings. The drawings are for illustrative purposes only and are not intended to limit the scope of protection. The scope of protection is defined only by the appended claims.

Brief Description of the Drawings

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Mode for Carrying Out the Invention

[0063] Hereinafter, elements having the same or similar functions are denoted by the same reference numerals.

[0064] The principle of the present invention in the case of a fuel cell stack will be described below, where the electric plate is a bipolar plate and the insulating layer is a membrane electrode assembly. However, this principle can be similarly applied to any other type of battery or battery stack. Furthermore, the features illustrated for one embodiment can be included alone or in combination with other embodiments.

[0065] FIG. 1 shows a voltage monitoring device 1 for a fuel cell stack 2. The fuel cell stack 2 includes a plurality of bipolar plates 4-1 to 4-5 sandwiching membrane electrode assemblies 6-1 to 6-4. The fuel cell stack 2 generates a total voltage as a result of the individual voltages of each of the bipolar plates 4-1 to 4-5. Since the bipolar plates 4-1 to 4-5 may wear over time and the generated total voltage depends on each of the bipolar plates 4-1 to 4-5, it is necessary to monitor the generated voltage.

[0066] For this purpose, the voltage monitoring device 1 includes a plurality of voltage monitoring units 8-1 to 8-5, preferably one for each of the bipolar plates 4-1 to 4-5, and a plurality of support elements 20 (see FIG. 4 for example). Each voltage monitoring unit 8-1 to 8-5 includes contact elements 22-1 to 22-5. Each support element 20 supports at least one of the contact elements 22-1 to 22-5. Each of the contact elements 22-1 to 22-5 is in contact with one of the plurality of bipolar plates 4-1 to 4-5. Several possibilities of connecting the contact elements 22-1 to 22-5 to the bipolar plates 4-1 to 4-5 are explained with reference to FIGS. 4 to 17. Through the contact elements 22-1 to 22-5, the respective voltages of the bipolar plates 4-1 to 4-5 are taken out and transmitted to the first signal path interruption elements 42-1 to 42-5. The first signal path interruption elements 42-1 to 42-5 are arranged on a first signal line 44 configured to transmit a first signal to a processing unit 46.

[0067] In the following, the signal is an electrical signal, and the signal path interruption element is an electrical switch, such as a transistor. However, it should be noted that the signal may be an optical signal, and the signal path interruption element may be an electromechanical switch such as a piezo element. The following description also applies to such embodiments. Further, in the following, the signal path interruption element is configured to interrupt signal transmission when one electrical plate does not operate as intended. However, the following description can also be similarly applied to embodiments in which the signal path interruption element is configured to transfer a signal when an electrical plate does not operate as intended and to interrupt signal transmission when the electrical plate operates properly.

[0068] The signal may be generated from a power source, such as a voltage source. Alternatively, the voltage of the first bipolar plate 4-1 may be used as the signal transmitted on the signal line 44. The first signal line 44 supplies the first signal to the processing unit 46. The processing unit 46 can determine whether the fuel cell stack 2 is operating properly based on the received signal, as will be described in more detail below.

[0069] The first signal path interruption elements 42-1 to 42-5 receive the respective voltages of the bipolar plates 4-1 to 4-5 via the contact elements 22-1 to 22-5. In response to the respective voltages, each of the first signal path interruption elements 42-1 to 42-5 transfers or interrupts the signal on the first signal line 44. If all the generated voltages are sufficient, all of the first signal path interruption elements 42-1 to 42-4 transfer the signal to the next first signal path interruption elements 42-2 to 42-5, respectively, and the last one of the first signal path interruption elements 42-5 transfers the signal to the processing unit 46.

[0070] The signal path cutoff elements 42-1 to 42-5 can be realized, for example, using an electrical switch that opens when the voltage is below the threshold value and closes when the voltage is above the threshold value. In the former case, the signal line 44 is cut off, and in the latter case, the signal line 44 is closed, and the signal is transferred to the next signal path cutoff elements 42-2 to 42-5, respectively. For example, the signal path cutoff elements 42-1 to 42-5 may be transistors, and when the voltages of the contact elements 22-1 to 22-5 are applied to the base of the transistor and the applied voltage exceeds the threshold value, depending on the type of transistor, a voltage flow from the emitter to the collector or vice versa will occur.

[0071] For example, when the voltage of the bipolar plate 4-2 is below the reference threshold voltage, the corresponding first signal path cutoff element 42-2 cuts off the transmission of the signal on the first signal line 44. In this case, even if the other first signal path cutoff elements 42-1, 42-3 to 42-5 remain closed, that is, even if the signal continues to be transferred while connecting the first signal line 44, since the first signal line 44 is cut off by the first signal path cutoff element 42-2, the processing unit 46 does not receive any signal. At that time, the processing unit 46 will output a warning signal indicating that at least one of the bipolar plates 4-1 to 4-5 is not operating as intended.

[0072] The processing unit 46 cannot determine which of the bipolar plates 4-1 to 4-5 is not operating as intended, and can only determine that some plate is not operating as intended. However, it should be noted that this information may be sufficient because in any case, it may be necessary to disassemble the entire fuel cell stack. A more detailed evaluation of the bipolar plates 4-1 to 4-5 can be performed after disassembling the entire stack 2. Alternatively, even more detailed evaluation can also be performed by installing additional evaluation units for individually evaluating the bipolar plates before disassembling the entire fuel cell stack. For example, such evaluation units may be attached to each of the bipolar plates 4-1 to 4-5 for further inspection of the individual bipolar plates 4-1 to 4-5.

[0073] As shown in FIG. 2, the voltage monitoring device 1 can further include voltage fluctuation flattening elements 48-1 to 48-5 in order to protect the first signal path interruption elements 42-1 to 42-5. The voltage fluctuation flattening elements 48-1 to 48-5 are connected in series between the contact elements 22-1 to 22-5 and the first signal path interruption elements 42-1 to 42-5, and are configured to transmit the voltages of the respective contact elements 22-1 to 22-5 to the first signal path interruption elements 42-1 to 42-5 when the voltage exceeds the flattening threshold voltage. Therefore, voltage fluctuations will be filtered and will not affect the downstream signal path interruption elements 42-1 to 42-5. The voltage fluctuation flattening elements 48-1 to 48-5 may be, for example, resistors.

[0074] In a further embodiment, as shown in FIG. 3, the voltage monitoring device 1 includes an additional second signal line 50 that is connected in parallel to the first signal line 44 and is also connected to the processing unit 46. The signal transmitted on the first signal line 44 may have the same origin as the signal transmitted on the second signal line 50, or may have a different origin, for example, a voltage source. Each voltage monitoring unit 8-1 to 8-5 includes second signal path interruption elements 52-1 to 52-5, which are arranged on the second signal line 50 and are connected in parallel to the respective first signal path interruption elements 42-1 to 42-5. Preferably, the first and second signal path interruption elements 42-1 to 42-5 and 52-1 to 52-5 are adapted to different threshold reference voltages.

[0075] As described with respect to FIG. 2, each voltage monitoring unit 8-1 to 8-5 may further include second voltage fluctuation flattening elements 54-1 to 54-5 that are connected in series between the contact elements 22-1 to 22-5 and the second signal path interruption elements 52-1 to 52-5. Similar to the voltage fluctuation flattening elements 48-1 to 48-5, the second voltage fluctuation flattening elements 54-1 to 54-5 also serve to protect the second signal path interruption elements 52-1 to 52-5 by filtering voltage fluctuations. It should be noted that the voltage fluctuation flattening elements 48-1 to 48-5 and 54-1 to 54-5 are optional and may be omitted.

[0076] The first and second signal lines 44, 50 may be used to provide a stepped warning system. This means that the first signal line 44 and the second signal line 50, and their corresponding signal path interruption elements 42-1 to 42-5 and 52-1 to 52-5, are each adapted to different reference voltage thresholds. For example, when the voltage generated by one of the bipolar plates 4-1 to 4-5 (e.g., 4-2) falls below a first reference threshold voltage, the corresponding first signal path interruption element 42-2 interrupts the transmission of the first signal because the voltage supplied to the first signal path interruption element 42-2 falls below the required first reference threshold voltage. In this way, the signal transmission of the first signal line 44 is interrupted, and the processing unit 46 determines that it receives the signal of the signal line 50 but does not receive the signal of the signal line 44. The processing unit 46 will then output a pre-warning signal indicating that one of the bipolar plates 4-1 to 4-5 has reached a critical state but is still functioning.

[0077] When the voltage generated by the bipolar plate 4-2 also falls below a lower second reference threshold voltage, the corresponding second signal path interruption element 22-2 also interrupts the transmission on the second signal line 50, and the processing unit 46 determines that it is necessary to disassemble the fuel cell stack 2 and replace at least one of the bipolar plates 4-1 to 4-5.

[0078] The voltage monitoring device 1 can include two or more signal lines 44, 50 having corresponding signal path interruption elements, and thus can be upscaled as needed. Depending on the number of signal lines, more detailed monitoring with various warning levels can be achieved.

[0079] The contact elements 22-1 to 22-5 are arranged within the fuel cell stack 2. Further elements, namely the signal path interruption elements 42, 52, the voltage fluctuation leveling elements 48, 54, and the signal lines 44, 50, can be arranged either within the fuel cell stack 2, particularly within or on the support element 20, or externally. Also, some elements are arranged within the fuel cell stack 2, particularly within or on the support element 20, and some elements can be arranged outside the fuel cell stack 2. Some exemplary embodiments of the various arrangements are shown in FIGS. 4 to 17 below.

[0080] FIGS. 1 to 13 partially show the fuel cell stack 2 having at least one bipolar plate 4. An example of such a bipolar plate is shown in FIG. 14, which is a simplified schematic plan view of the bipolar plate 4 of the fuel cell stack 2 according to any of the above exemplary embodiments. Each bipolar plate 4 is typically a combination of an anode plate and a cathode plate fixed to each other. Each anode and cathode plate has a front side and a back side, where the front, i.e., the reactant side, faces the adjacent membrane electrode assembly (not shown in FIG. 14), and the back, i.e., the coolant side, faces each other. Further, each bipolar plate 4 has a plurality of openings 60, 62, i.e., manifolds, for supplying (opening 60) and discharging (opening 62) reactants and coolant to and from the bipolar plate 4. To distribute the reactants and coolant across the entire plate, the bipolar plate may further have a protruding structure (not shown) forming a fluid flow field 64 for each reactant / coolant. To seal the flow field from the environment, the plate further comprises a bead seal 10 that can protrude from the base 12 of the plate and extend over the height of the flow field structure (see also FIGS. 4 to 13).

[0081] Each bipolar plate 4 is sandwiched between a first membrane electrode assembly 6-1 and a second membrane electrode assembly 6-2. The membrane electrode assembly 6 corresponding to the insulating layer 6 in FIGS. 1 to 3 is usually a multilayer membrane electrode assembly, but for simplicity, it is shown in the figures as a single layer. The bipolar plate 4 is further shown to have protruding structures 10, 14 that protrude beyond the bases 12 (anode side), 16 (cathode side) of the bipolar plate 4, for example, bead seals or channel-like structures of the flow field.

[0082] As described above, a support element 20 is provided to hold the contact elements 22 in FIGS. 1 to 3. FIGS. 1 to 9 show various preferred embodiments of such a support element 20. Each support element 20 includes at least one contact element 22 disposed on the surface of the support element 20 and configured to contact the bipolar plate 4. For simplicity, the contact element 22 is shown only schematically in the drawings. It should be noted that each contact element 22 can include a wire (not shown) for connecting to a corresponding signal line 44, 50 via corresponding signal path blocking elements 42, 54.

[0083] To attach the support element 20 to the bipolar plate 4, the bipolar plate 4 is provided with through holes 18 through which the support element 22 can be inserted and passed through. As can be seen in FIG. 14, the bipolar plate 4 includes two through holes 18, 19 disposed on the diagonal of the bipolar plate 4.

[0084] Furthermore, in the illustrated embodiment, the support element 20 is made of an electrically insulating material, while the contact element 22 is made of a conductive material. The electrically insulating material may be a plastic material, and the support element 20 may be molded or injection molded. The contact element 22 may be made of copper. Furthermore, the contact element 22 may be an elastic element, and preferably, the contact element 22 is elastically molded. For example, the contact element 22 may be molded as a spring, which is schematically shown by a semi-circular contact element in FIGS. 4 to 13.

[0085] As shown in Fig. 4, in a very simple form, the support element 20 has a base plate 24 on which the contact elements 22 are arranged such that the contact elements 22 each contact the respective bipolar plate 4. Further, as can be seen from Fig. 4, the height h b of the base plate 24 and the height h c of the contact elements 22 are such that the total height h b +h c of the base plate 24 and the contact elements 22 is less than the height h シール of the protruding portion 14 of the bipolar plate 4, for example, the height h シール of the bead seal (h b >h c +h

[0086] As shown in Figs. 5 to 13, in a further embodiment, the support element 20 has a base plate 24 and a protruding portion 26. The protruding portion 26 is recessed from the base plate 24 such that a step 28 is formed between the base plate 24 and the protruding portion 28. Further, the contact element 22 can be arranged on the base plate 24, particularly on the step 28, or on the protruding portion 26 as will be described later. In either case, the contact element 22 is in contact with the respective bipolar plate 4.

[0087] The height h p of the protruding portion of the support element 20 can be designed such that the support element 20 does not penetrate through the entire bipolar plate 4 (see Fig. 5), or can be designed such that the support element 20 penetrates through the entire bipolar plate 4 (see Fig. 6). However, in either case, the height H VM of the support element 20 is such that it does not protrude beyond the height H BPP of the bipolar plate 4 at any position: H BPP >H VM .

[0088] As can be seen in the embodiment shown in FIG. 7, the contact element 22 can be arranged, as shown in the figure, not at step 28 but at various locations, for example, on the side surface of the protruding portion 26. Further, as can be seen in FIG. 7 and FIGS. 8 to 11, the support element 20 may include a cover portion 30. The cover portion 30 is designed to fix the support element 20 to the bipolar plate 4. This enables pre - attachment of the support element 20 before stacking of the fuel cell stack.

[0089] In the embodiment of FIG. 7, the cover portion 30 may be an integral part of the support element 20 and designed as a hook 32 configured to be snap - fastened onto the edges of the through - holes 18, 19 of the bipolar plate 4. Alternatively, the cover portion 30 may be designed as a separate element that can interact with the protruding portion 26 of the support element 20, as shown in FIGS. 8 to 10. In this regard, for example, as shown in FIG. 7, the cover portion 30 may include a connecting portion 34. In the illustrated embodiment, the connecting portion 34 is designed as a protrusion that can be received within a recess (not shown) provided in the protruding portion 26 of the support element 20 to securely fix the cover portion 30 to the protruding portion 26. Of course, other connectable configurations are equally possible. For example, the cover portion 30 may further include a recess that interacts with the protruding portion 26.

[0090] In all cases, it is preferable that the cover portion 30 and the protruding portion 26 interact such that they are fixed to each other, for example, by press - fitting, friction - fitting, etc. Therefore, additional elements such as snap elements may be provided on the protruding portion 26 or on the cover portion 30. The cover portion 30 and the protruding portion 26 can also be joined to each other, for example, by adhesion or welding.

[0091] When the support element 20 includes the cover portion 30, it is of course also possible to arrange the contact element on the cover portion (for example, see FIG. 9), on both the cover portion 30 and the base portion 24 (for example, see FIG. 10), or on any other surface of the support element 20.

[0092] As described above, each bipolar plate 4 of the exemplary embodiments of FIGS. 5 to 13 has at least one opening 18, 19 configured to accommodate the protruding portion 26 of the support element 20. The support element 20 is configured to be fixed to the bipolar plate 4. In an embodiment not shown, the support element 20 may be further configured to be fixed to or be an integral part of the membrane electrode assembly 6 of the fuel cell stack 1, and in particular, may be a part of the sub-gasket surrounding the membrane electrode assembly 6.

[0093] In addition to its function as a support element, the support element 20 can also be used as a stacking and alignment assistance. Therefore, the support element may have a structure that enables the interaction between one support element 20-1 and an adjacent support element 20-2. FIGS. 11 to 13 show various embodiments of the support elements 20-1, 20-2 with additional alignment mechanisms.

[0094] As shown in FIGS. 11 to 13, if such stacking and alignment assistance is provided, the membrane electrode assembly 6 also preferably has a through hole 40, and a part or a portion of the support element 20-1 can extend therethrough for interaction with an adjacent support element 20-2.

[0095] Furthermore, for the interaction between two adjacent support elements 20-1, 20-2, as shown in FIGS. 11 and 13, it is more preferable that the support element 20 further has a recess 36 on the opposite side of the protruding portion. In this regard, it is more preferable that the dimensions and / or shape and / or depth of the recess 36 are configured to accommodate the protruding portion 26 of the adjacent support element. This enables the stacking of the support elements 20-1, 20-2 on top of each other, and automatically results in the alignment of the bipolar plate 4 and the membrane electrode assembly 6 between the layers.

[0096] FIG. 11 shows one embodiment, and the cover portion 30 described with reference to FIGS. 8 to 10 above includes a protrusion portion 38 that extends through a through hole 40 provided in the membrane electrode assembly 6 on the side facing the membrane electrode assembly. This protrusion portion 38-1 is received in the recess 36-2 of the adjacent support element 20-2, enabling not only the alignment of the membrane electrode assembly 6 with respect to the bipolar plate 4 but also the alignment of the bipolar plate 4-1 with respect to the bipolar plate 4-2.

[0097] All of the contact elements 22 shown in FIGS. 4 to 10 are connected to corresponding signal path interruption elements 42 (not shown in FIGS. 4 to 10). The signal path interruption element 42, and optionally the voltage fluctuation leveling element 48 as well, can be arranged within the support element 20. In that case, the wires from the signal path interruption element 42 are led to the outside and the signal line 44 (not shown), or they can be arranged outside the fuel cell stack 2. In that case, the wires from the contact element 22 are led to the outside and the corresponding signal path interruption element 42.

[0098] In FIG. 11, the signal path interruption elements 42-1, 42-2 are arranged within the support elements 20-1, 20-2. Alternatively, the signal path interruption elements 42-1, 42-2 can also be arranged on the surfaces of the support elements 20-1, 20-2. The signal line 44 is led through the fuel cell stack 2, particularly within the support elements 20-1, 20-2, from the signal path interruption element 42-1 towards the signal path interruption element 42-2, crossing the bipolar plates 4-1, 4-2 and the membrane electrode assemblies 6-2, 6-3. For this purpose, the support elements 20-1, 20-2 may be connected by pins 56 or the like. The pins 56 can be used to electrically connect the wire that is the signal line 44, and this wire is led from the signal path interruption element 42-1 to the signal path interruption element 42-2 and further to a processing unit 46 from a signal path interruption element (not shown). The contact elements 22 are each connected to the corresponding signal path interruption element 42 via a wire 58. Also, although not shown, the voltage fluctuation leveling element 48 can be arranged within the support element 20 together with the signal path interruption element 42.

[0099] Alternatively, the signal line 44 may be an optical fiber or may be an aperture for guiding light from the first signal path blocking element 42-1 to the processing unit 46 through the bipolar plate 4 and the membrane electrode assembly 6.

[0100] In the embodiments of FIGS. 12 and 13, the support element 20 extends beyond a single bipolar plate 4 and spans three bipolar plates 4-1, 4-2, 4-3 in FIG. 12 and two bipolar plates 4-1, 4-2 in FIG. 13.

[0101] As shown in FIG. 12, one support element 20 can be used to contact a plurality of bipolar plates 4-1 to 4-3. In this embodiment, the voltages of the three bipolar plates 4-1 to 4-3 are detected and transferred to one signal path blocking element 42-1. Thus, rather than individually blocking the signal line 44 based on the voltages of each bipolar plate 4-1, 4-2, 4-3, the signal path blocking element 42-1 blocks (or transfers) the signal on the signal line 44 based on the accumulation of the voltages of a subgroup of the bipolar plates 4-1 to 4-3.

[0102] In FIG. 13, the protruding portion 26 of the support element 20 includes a first portion 26-1 and a second portion 26-2 that are recessed with respect to each other to form a further step 27. As can be further seen, the support element 22 has a first contact element 22-1 at the original step and a second contact element 22-2 at the further step 27, the first contact element being configured to contact the first bipolar plate 4-1 and the second contact element 22-2 being configured to contact the second bipolar plate 4-2.

[0103] Furthermore, each bipolar plate 4 has a first opening 18 configured to receive the first portion 26-2 of the protruding portion 26 of the support element 20, and a second opening 19 configured to receive the second portion 26-2 of the protruding portion 26 of the support element 20. The first and second bipolar plates 4-1, 4-2 are arranged such that the first opening 18 of the first bipolar plate 4-1 is aligned with the second opening 19 of the second bipolar plate 4-2.

[0104] Furthermore, as shown, the second portion 26-1 of the protruding portion 26 can be received within the recess 36-2 of the adjacent support element 20-2, thereby enabling automatic alignment of the bipolar plate 4 and the membrane electrode assembly 6. Furthermore, it should be noted that in the present embodiment, the membrane electrode assembly 6 further comprises two through-holes 40, 41 of different dimensions. Thus, the membrane electrode assembly 6-2 has a through-hole 40 having a first dimension, and the membrane electrode assembly 6-3 has a through-hole 41 having a dimension different from that of the through-hole 40. Similar to the through-holes 18, 19 of the bipolar plate, the dimensions and shapes of the through-holes may be adapted to the dimensions and shapes of the first and / or second portions 26-1, 26-2 of the protruding portion 26.

[0105] It should be noted that even if the contact element 22 is arranged in steps, it is also possible to arrange the contact element on other suitable surfaces of the support element 20 or the cover portion 30. Furthermore, although some elements of the voltage monitoring unit 8 are shown only illustratively in FIGS. 11 and 12, it should be noted that these can be incorporated into all the embodiments shown in FIGS. 1 to 17.

[0106] In the embodiments described in FIGS. 14 to 17, the through holes 18 and 19 of the bipolar plate 4 function as a first alignment through hole 18 and a second alignment through hole 19, and the first alignment through hole 18 is arranged at a position different from that of the second alignment through hole 19. In FIG. 14, the first alignment through hole 18 is arranged at the opposite pole to the second alignment through hole 19. Thus, the first and second alignment through holes 18 and 19 are symmetric with respect to a 180° rotation around the normal to the surface of the bipolar plate 4.

[0107] As further shown in FIG. 14, the first alignment through hole 18 has an elongated shape, while the second alignment through hole 19 has a circular shape. Thus, both through holes differ in shape and dimensions. However, it is also possible that both the first and second alignment through holes 18 and 19 have an elongated shape, in which case the longitudinal axis of the first alignment through hole 18 is orthogonal to the longitudinal axis of the second alignment through hole 19.

[0108] FIGS. 15 to 17 each show a schematic cross-sectional view passing through the alignment through holes 19 and 18 along line II-II of FIG. 14. Further, the embodiments of the fuel cell stack 2 shown in FIGS. 15 to 17 show a special stacking order of the bipolar plates and the membrane electrode assemblies. That is, since all even-numbered bipolar plates 4-2, 4-4... are rotated by 180° with respect to the bipolar plates 4-1, 4-3..., the first alignment through holes 18-1, 18-3... of the first bipolar plates 4-1, 4-3... coincide with the second alignment through holes 19-2, 19-4... of the second bipolar plates 4-2, 4-4.... The same also applies to the membrane electrode assemblies 6 and their through holes 40 and 41.

[0109] As can also be seen in FIGS. 15 to 17, the overall height H of the support element 20 VM is at least two cell pitches d = H MEA + H BPPIt is designed as described above. One cell pitch is defined as the distance between two unit fuel cells. Each unit fuel cell is composed of a bipolar plate 4 and a membrane electrode assembly 6: H VM ≧2×(H MEA +H BPP ).

[0110] In the embodiments shown in FIGS. 15 and 16, the heights h a1 , h a2 of the protruding portions 26-1 and 26-2 are designed differently. The height h a1 of the first protruding portion 26-1 is close to one cell pitch (h a1 ≒H BPP +H MEA ), and the height h a2 of the second protruding portion 26-2 is greater than one cell pitch (h a2 ≧H BPP +H MEA ). In this embodiment, it is preferable that the membrane electrode assembly 6 further includes first and second alignment through-holes 40 and 42 having different dimensions and shapes.

[0111] As can be seen in FIGS. 15 to 17, the dimensions of the first protruding portion 26-1 will be close to the dimensions of the first alignment through-hole 18 of the bipolar plate 4, and the dimensions of the second protruding portion 26-2 will be close to the dimensions of the second alignment through-hole 19 of the bipolar plate 4. The same also applies to the membrane electrode assemblies 6 and their through-holes 40 and 41.

[0112] Referring further to FIG. 15, the support elements 2 are alternately arranged on the bipolar plates 4. That is, in the bipolar plate 4-1, the first support element 20-1 is arranged in the first alignment through-hole 18-1 of the first bipolar plate 4-1, so that the base plate 24 contacts the first bipolar plate 4-1, and the first protruding portion 26-1 of the first support element 20-1 extends through the first alignment through-hole 18-1. Similarly, the second support element 20-2 is arranged in the second alignment through-hole 19-1 of the first bipolar plate 4-1, and its second protruding portion 26-2 extends through the second alignment through-hole 19-1 of the first bipolar plate 4-1.

[0113] In the adjacent bipolar plate 4-2, the situation is the same, but since the bipolar plate 4-2 is rotated by 180°, the alignment through-holes 18-2, 19-2 are reversed. Therefore, the second protruding portion 26-2 of the first support element 20-1 extends through the corresponding second alignment through-hole 19-2 of the second bipolar plate 4-2, while the base plate 24 of the third support element 20-3 is arranged in the first alignment through-hole 18-2 of the second bipolar plate 4-2, and its first protruding portion 26-2 extends through the first alignment through-hole 18-2 of the second bipolar plate 4-2.

[0114] In the case of the third bipolar plate 4-3, or generally the (2n - 1)-th bipolar plate in the stack, the situation is the same as that of the first bipolar plate, and in the case of the fourth bipolar plate 4-4, or generally the 2n-th bipolar plate, the situation is the same as that of the second bipolar plate 4-2.

[0115] In contrast to FIG. 15, in the arrangement of FIG. 16, the first support element 20-1 contacts the first and second bipolar plates 4-1, 4-2, while the second support element 20-2 contacts the third and fourth bipolar plates 4-3, 4-4. In the alternative arrangement shown in FIG. 17, the first support element 20-1 contacts the first bipolar plate 4-1, the second support element 20-2 contacts the second bipolar plate 4-2, the third support element 20-3 contacts the third bipolar plate 4-3, and the fourth support element 20-4 contacts the fourth bipolar plate 4-4. As can be seen in FIG. 17, the support elements 20-1, 20-4 and 20-2, 20-3 have different dimensions to enable the alignment of the bipolar plate 4.

[0116] By alternately contacting the bipolar plates 4, the space required for the fuel cell stack 2 can be reduced, and for example, more space can be provided to accommodate additional elements such as signal path interruption elements.

[0117] Although not shown in FIGS. 15 to 17, it should be noted that each support element 20 includes a contact element 22 and can also include additional elements, namely, signal path interruption elements and the like, as described in connection with FIGS. 4 to 13.

[0118] In summary, the disclosed support elements enable easy and reliable placement of the support elements on the bipolar plates. Furthermore, any misplacement of the electrical contact elements can be avoided, thereby avoiding any damage to the fuel cell stack due to misplacement.

Claims

1. A voltage monitoring device (1) for a battery stack (2) comprising a plurality of electrical plates (4) sandwiching an insulating layer (6), the voltage monitoring device (1) being configured to monitor the voltage of at least one electrical plate (4) of the battery stack (2), and the voltage monitoring device (1) comprising at least one voltage monitoring unit (8) having a contact element (22) in contact with the at least one electrical plate (4). The voltage monitoring device (1) includes a first signal line (44) configured to supply a first signal from a signal source to a processing unit (46), the voltage monitoring unit (8) includes a first signal path interruption element (42) disposed on the first signal line (44), the first signal path interruption element (42) is connected to the contact element (22), and is configured to transfer the first signal depending on the voltage present in the at least one electrical plate (4). The voltage monitoring device (1) includes a support element (20) designed to be disposed within the battery stack, the support element (20) being configured to support at least the contact element (22). A voltage monitoring device characterized by this.

2. The voltage monitoring device according to claim 1, wherein the support element (20) is made of an electrically insulating material and the contact element (22) is made of a conductive material.

3. The voltage monitoring device according to claim 1 or 2, wherein the support element (20) comprises the voltage monitoring unit (8).

4. The voltage monitoring device according to any one of claims 1 to 3, wherein the support element (20) is configured to be disposed above and / or within a through hole provided in at least one of the electrical plates (4).

5. The support element (20) has a base plate (24) and a protruding portion (26), and since the protruding portion (26) is recessed from the base plate portion (24), a step (28) is formed between the base plate (24) and the protruding portion (26). In particular, the support element (20) is configured to be stacked on a further support element (20). In particular, the support element (20) has a recess (36) on the opposite side of the base plate (24) from the protruding portion (26), and this recess is dimensioned to accommodate the protruding portion (26) of an adjacent support element (20), so that one support element (20) is configured to be stacked on a further support element (20). In particular, the support element (20) includes pins for electrically connecting to the further support element (20). The voltage monitoring device according to any one of claims 1 to 4.

6. The support element (20) includes through holes (18, 19) configured to accommodate cables and / or transmit light. The voltage monitoring device according to any one of claims 1 to 5.

7. The contact element (22) is arranged on the base plate (24), preferably on the step (28) and / or on the protruding portion (26), such that the contact element (22) contacts the electrical plate (4). The voltage monitoring device according to any one of claims 5 to 9.

8. The first signal path interruption element (42) is arranged on or within the support element (20). In particular, the first signal line (44) is arranged within the support element (20). The voltage monitoring device according to any one of claims 1 to 7.

9. The voltage monitoring unit (8) includes a voltage fluctuation leveling element (48) arranged between the contact element (22) and the first signal path interruption element (48) and configured to transmit a voltage from the contact element (22) to the first signal path interruption element (42) when the voltage exceeds a leveling threshold voltage. In particular, the voltage fluctuation leveling element (48) is arranged on and / or within the support element (20). The voltage monitoring device according to any one of claims 1 to 8.

10. The voltage monitoring device (1) includes a plurality of voltage monitoring units (8), each of which includes a contact element (22) in contact with one of the plurality of electrical plates (4). The voltage monitoring device (1) includes a plurality of support elements (20), each of which supports at least one contact element (22). The voltage monitoring device according to any one of claims 1 to 9.

11. Each voltage monitoring unit (8) includes a first signal path interruption element (42) disposed on the first signal line (44). Each of the first signal path interruption elements (42) is connected to the corresponding contact element (22) and is configured to transfer the first signal depending on the voltage present on the corresponding electrical plate (4). The first signal path interruption elements (42) of the plurality of voltage monitoring units (8) are connected in series. The voltage monitoring device according to claim 15.

12. A subgroup of the voltage monitoring units (8) includes a first signal path interruption element (42) disposed on the first signal line (44). Each of the first signal path interruption elements (42) is connected to a plurality of corresponding contact elements (22) and is configured to transfer the first signal depending on the voltage present on the corresponding electrical plates (4) in contact with the plurality of corresponding contact elements (22). The first signal path interruption elements (42) of the plurality of voltage monitoring units (8) are connected in series. The voltage monitoring device according to claim 15.

13. Two support elements (20) that support contact elements (22) in contact with two adjacent electrical plates (4) are disposed at different ends of the battery stack (2). The voltage monitoring device according to any one of claims 15 to 17.

14. The voltage monitoring device (1) includes a second signal line (50) connected in parallel with the first signal line (44). The voltage monitoring unit (8) includes a second signal path interruption element (52) disposed on the second signal line (50) and connected in parallel with the first signal path interruption element (42). In particular, the first signal path interruption element (42) is configured to transfer or interrupt the first signal when the voltage of the at least one electrical plate (4) exceeds a first reference threshold voltage, and the second signal path interruption element (52) is configured to transfer or interrupt the second signal when the voltage of the at least one electrical plate (4) exceeds a second reference threshold voltage. The voltage monitoring device according to any one of claims 1 to 13.

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