Housing for receiving at least one fuel cell stack

Abstract

The present invention relates to a housing (10) that houses at least one fuel cell stack (20). The fuel cell stack (20) includes a plurality of bipolar plates (34) arranged vertically overlapping each other and an electrolyte membrane (54). The housing (10) includes an inner side (12) facing the at least one fuel cell stack (20), on which stiffeners (14) are provided to increase the surface area of ​​the housing (10), or each bipolar plate (34) has a protrusion (36) within the at least one fuel cell stack (20). The invention also relates to the application of the housing in a fuel cell having at least one fuel cell stack (20) for driving an electric vehicle.

Description

Technical Field

[0001] This invention relates to a housing for receiving at least one fuel cell stack, the fuel cell stack comprising a plurality of bipolar plates and an electrolyte membrane arranged in a stacked manner, the housing having an inward orientation towards the at least one fuel cell stack. The invention also relates to the application of this housing in a fuel cell having at least one fuel cell stack for driving an electric vehicle. Background Technology

[0002] Fuel cells typically operate using gaseous hydrogen (H2) and almost always operate as a stack of multiple individual cells. These individual cells are typically sealed to each other using elastomeric seals. Typically, fuel cell stacks are used with up to 500 cells and just as many seals. During normal operation, a small amount of H2 escapes through these seals. In the event of damage to one or more of these seals, a much larger amount of gaseous hydrogen may escape. In both cases, there is a possibility of forming an explosive mixture. To prevent the buildup of an explosive mixture, the casing is typically ventilated with ambient air.

[0003] DE10001717C1 relates to a fuel cell system. The fuel cell system includes at least one fuel cell unit housed in a fuel cell housing, and / or, a cathode gas or cold start gas supply line or a cathode exhaust gas or anode exhaust gas recirculation line is supplied to the fuel cell unit. The fuel cell system is equipped with at least one Coanda flow amplifier to amplify the airflow used for ventilating the fuel cell housing, the cathode gas flow or cold start gas flow, the recirculated cathode exhaust gas flow, or the recirculated anode exhaust gas flow, and / or, the system is equipped with a ventilation device for a housing outside the fuel cell housing, in which components of the fuel cell system are assembled, wherein the ventilation device has a Coanda flow amplifier.

[0004] DE10031238A1 relates to a fuel cell system and a method of operating the same. At least one fuel cell unit is installed in a fuel cell housing, wherein a housing ventilation device is provided with a flushing medium supply line into the fuel cell housing and a flushing medium discharge line leading out of the fuel cell housing. An explosion-proof fan is located in the flushing medium supply line and / or the flushing medium discharge line, and / or, a ventilation device for a housing outside the fuel cell housing is provided with a flushing medium supply line into the housing and a flushing medium discharge line leading out of the housing. These are combined in the housing of the fuel cell system, wherein the ventilation device includes an explosion-proof fan.

[0005] In the event of an explosion within a closed container (such as the housing surrounding a fuel cell), a maximum explosion pressure of up to 8.5 barg can occur in a stoichiometric H2-air mixture. In practical applications, fuel cell stack housings are typically constructed in a rectangular shape, where the surface area of ​​the housing, along with other built-in devices such as sensor valves and pumps, contributes to increasing the surface area of ​​the housing.

[0006] Given the maximum expected explosion pressure of 8.5 barg, it is common practice to design the housing used to receive the fuel cell to withstand a pressure of 8.5 barg. This results in the use of relatively more material and consequently, a relatively high weight. Furthermore, pressure relief structures, particularly rupture discs, are integrated. Summary of the Invention

[0007] According to the present invention, a housing for receiving at least one fuel cell stack is provided, the fuel cell stack comprising a plurality of bipolar plates and an electrolyte membrane arranged in a stacked manner, the housing having an inner side facing at least one fuel cell stack. A stiffening portion is constructed on the inner side of the housing to increase the surface area of ​​the housing, or each bipolar plate within the at least one fuel cell stack has a protrusion.

[0008] The solution proposed according to the present invention can achieve a significantly increased surface area of ​​the shell. In particular, the increased surface area on the inner side of the shell can be achieved by providing ribs or small blocks on the inner side of the shell.

[0009] In another configuration of the solution proposed according to the invention, the stiffener extends longitudinally from the upper side of the shell toward the lower side of the shell. Alternatively, it is possible for the stiffener to extend laterally, i.e., parallel to the upper side of the shell, on the inner side of the shell. Furthermore, according to another embodiment, it is possible for the stiffener to extend diagonally from the upper side of the shell to the lower side of the shell on the inner side of the shell.

[0010] The common feature of all the above-described embodiments of the stiffening part is that by placing the stiffening part on the inside of the shell, the surface area of ​​the shell is significantly increased, which advantageously leads to a reduction in the maximum explosion pressure.

[0011] In an extended embodiment of the solution proposed according to the invention, a channel for ventilation flow is formed on the inner side of the housing and the outer side of at least one fuel cell stack. This channel extends between the housing and the fuel cell stack, allowing hydrogen that might escape from the individual fuel cells due to leakage to be discharged through ambient air. This channel can be formed, for example, by a slot formed by the length of a single rib of a stiffening portion on the inner side of the housing toward at least one fuel cell stack. Depending on the length of the single rib, a free space is maintained between the outer side of at least one fuel cell stack and the inner side of the housing, forming the channel for ventilation flow.

[0012] In an extended embodiment of the solution proposed according to the present invention, an insulating layer may be extended between the inner side of the housing and the outer side of at least one fuel cell stack.

[0013] In the solution proposed according to the invention, when implementing the channel for ventilation flow, it is possible for the channel to be represented by a notch in a single rib of the stiffening portion, such that the ventilation flow passes through the channel from the single rib of the stiffening portion to the single rib, wherein individual cavities can be formed between the single ribs.

[0014] In an extended embodiment of the solution proposed according to the invention, at least one fuel cell stack is constructed of bipolar plates and an electrolyte membrane, wherein each bipolar plate may have a protrusion that protrudes toward the inside of the housing without contacting the inside.

[0015] In the solution proposed according to the invention, within at least one fuel cell stack, every second to tenth bipolar plate has the aforementioned protrusion. Thus, the ventilation channel between the inner side of the housing and the outer side of the fuel cell stack is formed, in a kinematically reversed manner, not by stiffeners extending on the inner side of the housing, but by individual protrusions extending from every second to tenth bipolar plate toward the inner side of the housing without contacting the housing or the insulation layer disposed there. This ensures that a gap, or free space, is always maintained for ventilation flow.

[0016] In the solution proposed according to the invention, the bipolar plate within the protrusion can be constructed with an enhanced material thickness, thereby resisting short circuits caused by bending of the bipolar plate.

[0017] Furthermore, the present invention relates to the application of a housing in a fuel cell having at least one fuel cell stack for driving an electrically driven vehicle.

[0018] The solution proposed according to the invention can significantly reduce the maximum explosion pressure within the casing of a fuel cell having at least one fuel cell stack. In the ideal case where the surface area is ideally large, the solution proposed according to the invention can eliminate the explosion and convert it into simple combustion with a lower pressure level. This also presents the possibility of using a casing with lower pressure resistance, thereby saving weight and materials.

[0019] The reduced pressure level also allows for the installation of a closed enclosure for the equipment, free from ventilation devices and inlets and outlets to the fan, H2 sensor, and explosion-proof fan. This significantly reduces equipment costs, in addition to the existing ventilation flow through the fuel cell.

[0020] According to the solution proposed in this invention, the inner side of the shell can be provided with stiffeners, which can extend in the transverse, longitudinal, or diagonal direction; on the other hand, it is possible for each bipolar plate in the stack structure of at least one fuel cell stack to have protrusions, thereby significantly increasing the surface area. The larger the surface area of ​​the shell on its inner side, or on the outer side of at least one fuel cell stack, the lower the explosion pressure can be achieved.

[0021] To avoid electrical contact between the individual bipolar plates and the inner side of the casing in at least one fuel cell stack, an insulating layer may be provided. Ventilation flow can be formed through its circulation channels, either through a notch in a single rib of the stiffener or through a single rib of a shortened structure of the stiffener, such that a gap is maintained between the end of the corresponding single rib and the outer side of the fuel cell stack opposite that end, through which ventilation flow can pass.

[0022] The solution proposed according to the invention can achieve, for example, explosion pressure levels from 5.4 barg to 2.8 barg, which helps to manufacture the casing of at least one fuel cell stack for receiving fuel cells significantly more advantageously, i.e. easier and less costly.

[0023] The housing can be reinforced by stiffening sections on its inner side, which advantageously allows the housing to function as a support structure for the entire fuel cell system. The gas volume is reduced by the stiffening sections on the inner side, which further helps to reduce explosion pressure. In cases where the alternatingly projecting bipolar plates within the fuel cell stack structure are not in electrical contact with the housing and are stably implemented, for example, with a large material thickness, the forces of the fuel cell stack can be transferred to the housing. Fuel cell stacks with multiple cells arranged horizontally tend to bend and are more sensitive to vibrations occurring during vehicle operation. This uneven bending and vibration loads the seals of these cells, potentially leading to unsealing. With the solution proposed according to the invention, this unsealing is largely mitigated by removing the flammable H2-air mixture. Attached Figure Description

[0024] Embodiments of the invention will be explained in more detail with reference to the accompanying drawings and the following description.

[0025] The attached diagram shows:

[0026] Figure 1 The inner side of a shell having a stiffened portion extending in the longitudinal direction;

[0027] Figure 2 A composite consisting of a fuel cell stack and a housing, wherein longitudinal stiffeners are provided on the inner side of the housing;

[0028] Figure 3 A top view of a fuel cell stack, which has stiffening sections extending longitudinally in the drawing plane within the casing;

[0029] Figure 4 A variant of the fuel cell stack in which each bipolar plate has a protrusion.

[0030] Figure 5 An enlarged view of a fuel cell stack having bipolar plates with protrusions that protrude toward the inside of the casing. Detailed Implementation

[0031] In the following description of embodiments of the present invention, the same or similar elements are denoted by the same reference numerals, and in some cases, repeated descriptions of these elements are omitted. The accompanying drawings are only schematic illustrations of the present invention.

[0032] Figure 1 The housing 10 is shown, with reinforcing ribs 14 provided on the inner side 12 of the housing. From the... Figure 1 As can be seen from the diagram, a reinforcing portion 14 having multiple individual ribs 33 extending in the longitudinal direction 16 extends on the inner side 12 of the housing 10. The reinforcing portion 14 extends from the upper side 22 to the lower side 24 of the housing 10 on the inner side 12 of the housing 10.

[0033] Figure 2 A composite consisting of at least one fuel cell stack 20 is shown, which is received in a housing 10 having a reinforcing section 14. Figure 2 As shown, on the inner side 12 of the housing 10, the individual ribs 33 of the stiffening portion 14 extend at equal intervals, particularly along the longitudinal direction 16. Alternatively, it is possible that the stiffening portion 14 extends not along the longitudinal direction 48, but also perpendicular to that longitudinal direction along the transverse direction 44 or along the diagonal direction 46, with a corresponding elongation on the inner side 12 of the housing 10, as shown. Figure 1 As shown in the image.

[0034] Figure 3 A top view of a fuel cell stack 20 is shown, which is received within a housing 10. To achieve an increase 40 in its inner surface 38, a stiffening portion 14 is constructed on the inner side 12 of the housing 10. This stiffening portion extends along the longitudinal direction 16, i.e., perpendicularly along the longitudinal direction 48 according to… Figure 3Extending in the drawing plane. Corresponding to the longitudinal extension of the individual ribs 33 of the stiffener 14 toward at least one fuel cell stack 20, a gap 26 is maintained between the outer sides of at least one fuel cell stack 20 comprising a plurality of bipolar plates 34 and an electrolyte membrane 54, which are received overlapping each other, and through which a ventilation flow 28 can pass. The ventilation flow 28 is primarily ambient air. The function of the ventilation flow 28 is to expel any possible gaseous leakage of gaseous hydrogen from the housing 10 to avoid the formation of an explosive mixture. From according to Figure 3 As shown in the diagram, cavities 30 are formed between the individual ribs 33 of the reinforcing portion 14 extending longitudinally 16. These cavities 30 are traversed by a ventilation flow 28 flowing in the ventilation direction 42, and any gaseous hydrogen that may accumulate there is removed from the respective cavities 30, which are part of a ventilation channel 56 to prevent the formation of an explosive mixture. The ventilation channel 56 connecting the cavities 30 to each other can be formed through various notches 52 in the individual ribs 33 of the reinforcing portion 14 on the inner side 12 of the housing 10. The ventilation flow 28, i.e., the ambient air, flows through the ventilation channel 56 in the ventilation direction 42, and allows any escaping hydrogen gas to leak out.

[0035] In addition, from Figure 3 As can be seen from the diagram, at least one fuel cell stack 20 includes a plurality of bipolar plates 34 and an electrolyte membrane 54. These bipolar plates and electrolyte membranes are arranged in a stacked manner in at least one fuel cell stack 20. Sealing elements, not shown in detail here, are provided between the individual bipolar plates 34 or electrolyte membranes 54.

[0036] An empirical correlation has been established between the actual surface area of ​​the shell and the volume of the enclosed gas. The maximum pressure is calculated as follows:

[0037] p max = -0.146O / V + 8.32.

[0038] Where, p max = Maximum explosion pressure (barg)

[0039] O = Total internal surface area (m²) 2 ),and

[0040] V = the volume of the enclosed gas (m³) 3 ).

[0041] For design reference, the fuel cell stack 20 and housing 10 can be considered to have the following dimensions: a stack with 400 cells and end plates, height x width x depth = 500 x 500 x 150 mm. 3 The casing 10 surrounding the fuel cell stack 20 has a height x width x depth of 520 x 520 x 170 mm. 3The surface area (rounded) of fuel cell stack 20 is 0.8 m². 2 The surface area (interior, rounded) of shell 10 is 0.9 m². 2 ; and the volume of the enclosed gas (rounded) = 0.85m 3 Considering the above values, the maximum explosion pressure is 5.4 barg. For this reason, the casing 10 must be designed for an explosion pressure of at least 5.4 barg, which will result in high material usage and correspondingly high weight.

[0042] If we now examine the shell 10 having the stiffener 14 proposed according to the present invention, we obtain the following values:

[0043] A fuel cell stack 20 with 400 individual cells and end plates, with a height x width x depth of 500 x 500 x 150 mm. 3 The casing 10 surrounding the fuel cell stack 20 has a height x width x depth of 520 x 520 x 170 mm. 3 The reinforcing part 14 has a transverse spacing x height x thickness = 10 x 10 x 1 mm. 3 The surface area of ​​the heap (rounded) is 0.8 m². 2 The internal surface area (rounded) of the shell 10 plus the stiffening part 14 is 2.2 m². 2 The volume of the enclosed gas minus the reinforced section 14 (rounded) = 0.79m. 3 .

[0044] Using the above data, a reduction in maximum explosion pressure of only 2.8 barg was obtained. This demonstrates significant potential for improvement, as the casing 10 can now be constructed to be significantly lighter, resulting not only in a significant reduction in weight used but also in a significant reduction in the cost of the materials used.

[0045] From the basis Figure 4 The illustration shows an embodiment of the fuel cell stack 20, which is constructed of multiple bipolar plates 34 and an electrolyte membrane 54. Figure 4 As shown, each bipolar plate in the stacked bipolar plates 34 has a protrusion 36. Figure 3 In contrast, by reversing the movement, a ventilation channel 56 between the inner side 12 of the housing 10 and the outer side of the fuel cell stack 20 can be achieved within the fuel cell stack 20 through corresponding protrusions 36 on every second to tenth bipolar plates 34 (see...). Figure 3The protrusions 36 are formed precisely by the bipolar plates 34. Each protrusion 36 of every second to tenth bipolar plate 34 may, for example, be provided with a notch 52, such that a ventilation channel 56 for a ventilation flow 28 can be formed between the inner side 12 of the housing 10 and the outer side of at least one fuel cell stack 20, the ventilation flow flowing in the ventilation direction 42. The ventilation channel 56 can also be constructed by leaving a gap 26 between the ends of each protrusion 36 of the bipolar plate 34 and the inner side 12 of the housing 10, through which cavities 30 are formed between the protrusions 36 of the bipolar plates 34, through which the ventilation flow 28 passes. This ensures, in this embodiment of the solution proposed according to the invention, the passage of the ventilation flow 28 is also ensured and the gaseous hydrogen that may accumulate in the cavities 30 is quickly removed without forming an explosive H2 / air mixture.

[0046] Figure 5 An enlarged illustration shows bipolar plates 34, each with a protrusion 36, within at least one fuel cell stack 20. Depending on the design of the at least one fuel cell stack 20, every second to tenth bipolar plate 34 may have a protrusion 36, forming a cavity 30. To avoid electrical short circuits, there is a possibility that the protrusions 36 are constructed with a greater material thickness, thus preventing bending of these protrusions and short circuits with adjacent bipolar plates 34. Furthermore, there is a possibility that at least one insulating layer 50 is pulled into the housing 10 between the inner side 12 of the housing 10 and the ends of the protrusions 36, or the ends of the bipolar plates 34, to prevent electrical short circuits. Figure 5 The top view also shows that an electrolyte membrane 54 is received between each bipolar plate 34 within at least one fuel cell stack 20. Figure 5 A gap 26 exists in cavity 30 shown in the figure (see according to Figure 3 (as illustrated), the cavity is defined by the construction of bipolar plates 34 to various protrusions 36 in the extra-long portion, the gap being passable by ventilation flow 28 along ventilation direction 42 and thus allowing gaseous hydrogen to be transported from the housing 10 in which at least one fuel cell stack 20 is arranged.

[0047] As another element for increasing surface area, corrugated sheet components, mesh, metal mesh, or honeycomb panels can be installed into the free gas volume, thereby significantly increasing the surface area. Simultaneously, the remaining free gas volume is significantly reduced. However, in this variation, the reinforcement effect of the housing 10 is omitted, and it can be applied as an additional measure to the above-described embodiment. Furthermore, it is possible to install, for example, an adhesively bonded honeycomb structure on the inner side 12 of the housing 10, thereby substantially reinforcing the housing 10.

[0048] This invention is not limited to the embodiments described herein and the aspects highlighted therein. Rather, numerous modifications within the scope of conventional techniques in the art can be made within the range given by the claims.

Claims

1. Housing (10) for receiving at least one fuel cell stack (20), which fuel cell stack comprises a plurality of bipolar plates (34) and electrolyte membranes (54) arranged on top of one another, the housing having an inner side (12) facing the at least one fuel cell stack (20), characterized in that A stiffening portion (14) is constructed on the inner side (12) of the housing (10) to increase the surface area of ​​the housing, wherein, on the inner side (12) of the housing (10), individual ribs (33) of the stiffening portion (14) extend across the entire surface at equal intervals, or, within the at least one fuel cell stack (20), each bipolar plate (34) has a protrusion (36) pointing toward the inner side (12) of the housing (10), and wherein corrugated sheet components, mesh, metal mesh or honeycomb panels are installed as additional elements to increase the surface area in the free gas volume between the housing (10) and the fuel cell stack (20), or a honeycomb structure is installed on the inner side (12) of the housing (10).

2. The housing (10) according to claim 1, characterized in that, The reinforcing part (14) extends along the longitudinal direction (48) from the upper side (22) to the lower side (24) of the inner side (12) of the shell (10).

3. The housing (10) according to claim 1, characterized in that, The reinforcing part (14) extends in the transverse direction (44) on the inner side (12) of the shell (10) about the upper side (22) of the shell (10).

4. The housing (10) according to claim 1, characterized in that, The reinforcing portion (14) of the inner side (12) of the housing (10) extends diagonally (46) from the upper side (22) of the housing (10) to the lower side (24) of the housing (10).

5. The housing (10) according to any one of claims 1 to 4, characterized in that, A ventilation channel (56) is formed between the inner side (12) of the housing (10) and the outer side of the at least one fuel cell stack (20) to enable ventilation flow (28).

6. The housing (10) according to claim 5, characterized in that, The ventilation channel (56) is formed by a gap (26) along the length (32) of a single rib (33) of the reinforcing part (14) toward the at least one fuel cell stack (20).

7. The housing (10) according to any one of claims 1 to 4 and 6, characterized in that, An insulating layer (50) extends between the inner side (12) of the housing (10) and the outer side of the at least one fuel cell stack (20).

8. The housing (10) according to claim 5, characterized in that, The ventilation channel (56) is formed by a notch (52) in a single rib (33) of the reinforcing part (14).

9. The housing (10) according to any one of claims 1 to 4, 6 and 8, characterized in that, The at least one fuel cell stack (20) consisting of bipolar plates (34) and an electrolyte membrane (54) includes bipolar plates (34) having protrusions (36) that extend toward the inside (12) of the housing (10) without contacting the inside.

10. The housing (10) according to claim 9, characterized in that, In the at least one fuel cell stack (20), every second to tenth bipolar plate (34) has the protrusion (36).

11. The housing (10) according to claim 9, characterized in that, The protrusion (36) on the bipolar plate (34) is implemented with a material thickness greater than that of the bipolar plate (34).

12. The use of the housing (10) according to any one of the preceding claims in a fuel cell having at least one fuel cell stack (20) for driving an electric vehicle.

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