Connecting device for connecting a fuel cell stack to a testing unit

Abstract

The invention relates to a connecting device for connecting a fuel cell stack (18) to a testing unit (10). The connecting device has an interface unit (22) connected to the testing unit (10) and comprising a main part (30), which has at least one through-opening (32), and at least one connecting part (36), which is secured to the main part (30) and has a connecting plate (38) provided with at least one fluid medium opening (40). The connecting device additionally has a movable support (26), to which the fuel cell stack (18) is secured and which is provided with a connecting surface (54) having a plurality of fluid medium inlets (58) and fluid medium outlets (60) that are fluidically connected to the fuel cell stack (18), and the connecting surface (54) of the support (26) can be moved against the at least one connecting plate (38) of the interface unit (22), or the connecting plate (38) of the interface unit (22) can be moved against the connecting surface (54) of the support (26). The at least one fluid medium opening (40) in the at least one connecting plate (38) corresponds to one of the fluid medium inlets (58) and / or fluid medium outlets (60) in the connecting surface (54) of the support (26) such that when the connecting surface (54) of the support (26) rests against the connecting plate (38), a fluidic connection is produced between the fluid medium inlet (58) and / or fluid medium outlet (60) in the connecting surface (54) and the at least one fluid medium channel (42) in the connecting part (36), said connecting plate (38) being at least indirectly resiliently secured to the main part (30).

Description

[0001] Connecting device for connecting a fuel cell stack to a test unit

[0002] The invention relates to a connecting device for connecting a fuel cell stack to a test unit.

[0003] Test units for testing fuel cells or fuel cell stacks typically include, in particular, an anode gas supply unit, a cathode gas supply unit, a conditioning unit, a control unit, and an evaluation unit, via which measured values ​​from the fuel cell or fuel cell stack can be recorded. Anode gas recirculation units for reducing anode gas consumption can also be part of the test unit.

[0004] Such test units are used, for example, for performance characterization, model validation, durability testing, degradation determination, quality assurance in production, or design verification. They can also be used to optimize fuel cell control. Cold start behavior, start-stop behavior, dynamic behavior, energy and thermal management, and fuel cell aging can be tested in different cycles. To be able to make such diverse statements, a defined supply of the appropriate media to the individual fuel cells or the fuel cell stacks under test must be ensured. These media must be regulated within a narrow pressure, temperature, humidity, and mass flow range depending on the operating point.

[0005] These test units simulate the entire periphery of the fuel cell, so only the fuel cell or fuel cell stack needs to be connected. However, the conventional methods of connecting the fuel cell stack to the test unit are very complex. Typically, the fuel cell stack is mounted on a support and contains an adapter plate on which the inlets and outlets for the anode and cathode gases are located. These are routed via flexible tubes to a docking plate and secured there. This connection between the fuel cell stack and the docking plate must be established and tested in a preparation zone.The docking plate must then be attached with its opposite side to a docking plate of the test unit, which in turn is connected to the test unit via piping, so that the flexible pipes coming from the fuel cell stack must be placed at the correct connections of the docking plates. However, this also means that the entire piping between the support or the fuel cell stack and the test unit must be tested and numerous connections must be made, resulting in long setup times and increased material and labor costs.

[0006] The task therefore arises to provide a connection device for connecting a fuel cell stack to a test unit that can reduce setup effort on the test bench and thus improve test bench utilization, allowing more test cycles to be performed per shift. At the same time, it is important to ensure that all connections are reliably sealed, while preventing setup errors. Furthermore, it is desirable to manufacture all media connections and all electrical connections with minimal effort. Costs due to labor and material expenditure should be reduced accordingly.

[0007] This object is achieved by a connecting device for connecting a fuel cell stack to a test unit with the features of main claim 1. The connecting device according to the invention for connecting a fuel cell stack to a test unit has an interface unit connected to the test unit via media pipes, for example in the form of hoses. The test unit typically has an anode gas supply unit and a cathode gas supply unit. These serve to provide and convey the hydrogen and the air or oxygen, respectively. Furthermore, the test unit has a conditioning unit, via which the fuel cell stack can be cooled to defined temperatures and, if necessary, also heated.A control unit is used to control and regulate the test unit, and an evaluation unit records and evaluates measured values ​​taken from the fuel cell or fuel cell stack. Of course, measured values ​​from a downstream energy storage unit or from additional pressure, temperature, or humidity sensors in the test unit can also be evaluated. The interface unit can either be permanently installed in the test unit or be arranged so that it can be moved relative to it. It consists of a base body, which can be plate-shaped in particular, and which has at least one through-hole.Furthermore, the interface unit consists of at least one connecting part that is attached to the base body and has a connecting plate in which at least one media opening is formed, which is fluidically connected to a media channel that is at least partially formed in the connecting part, but can also be partially formed by the through-opening in the base body. The at least one media channel extends from the media opening of the connecting plate facing the fuel cell stack, through the connecting plate and the at least one through-opening in the base body to the side of the base body facing away from the fuel cell stack, and is then connected to the test unit via the continuing media pipes.The media channel can either be formed only in the connecting piece, whereby the media channel extends through the through-openings but these do not directly define the media channel, or the connecting piece can terminate tightly at the through-openings, so that the media channel is subsequently defined by the through-openings. The rear connections of the media pipes are located either at the through-openings or directly at the connecting pieces.

[0008] Furthermore, the connecting device consists of a movable carrier to which the fuel cell stack is attached and on which a connection surface is formed, on which a plurality of media inlets and outlets are formed, which are fluidically connected to the fuel cell stack. These media inlets and outlets are, in particular, an anode gas inlet, an anode gas outlet, a cathode gas inlet, and a cathode gas outlet. If the test unit also has an anode gas recirculation blower, an additional anode gas outlet and an additional anode gas inlet can be provided. The carrier can be moved with its connection surface against the at least one connection plate of the interface unit, or the connection plate of the interface unit can be moved against the connection surface of the carrier. In particular, the carrier can be pulled towards the interface unit with the fuel cell stack guided.The at least one media opening of the at least one connection plate corresponds to one of the media inlets and / or media outlets of the connection surface of the carrier. By corresponding is meant that the shapes of the media inlets and outlets on the connection surface correspond to the shapes of the media openings on the connection part at least to the extent that when the connection surface moves against the interface unit, a tight fluidic connection is established between each media channel and exactly one of the media inlets or outlets. The movement of the carrier creates a state in which the carrier rests firmly against the connection plate with its connection surface. This firm contact establishes the fluidic connection between the media inlet and / or media outlet of the connection surface of the carrier and the at least one media opening or the at least one media channel of the interface unit.Of course, several connection parts can be formed on the base body, which in turn can each have several media channels, so that several fluidic connections can be established by docking the carrier with its connection surface to the connection parts.

[0009] According to the invention, the connecting plate is at least indirectly elastically attached to the base body. This means that at least the connecting plate or the entire connecting part can be moved elastically relative to the base body, in particular tilted. The attachment can be achieved, for example, via elastic damping elements, which can be arranged both between the connecting plate and the base body and between the base body and the other sections of the connecting part. Furthermore, additional parts can be arranged between the connecting part or the connecting plate and the base body, which enable this elastic movement of the connecting plate relative to the base body.

[0010] This elastic fastening dampens the docking process, protecting the fuel cell stack and preventing it from being subjected to shocks. Furthermore, alignment errors in all directions are corrected in the event of angular inaccuracies, ensuring a tight connection with adjustable contact pressure.

[0011] The connecting device according to the invention eliminates the need for expensive multi-coupling plates with various integrated couplings and additional equipment. Setup effort is significantly reduced because the connections can be established in a single setup step. This reduces the labor required and thus the labor costs for setting up the test bench, as well as the setup times, allowing significantly more test cycles to be achieved per shift. The required setup material and the testing effort for checking the connections are also reduced. In addition, the space required for both the test bench itself and the space required for the setup material are reduced. The reduced setup and test cycle times enable higher utilization of the test bench, thus reducing individual test costs.

[0012] The interface unit preferably has a plurality of connection plates that are at least indirectly elastically attached to the base body. This allows a secure and tight connection of the media inlets and outlets of the fuel cell stack to a plurality of connection plates to be established in a single step. Leaks are reliably compensated for by the elastic or flexible arrangement of the connection parts to the base body. Furthermore, multiple fuel cell stacks can be connected via multiple connection plates if necessary.

[0013] It is also advantageous if several media openings are formed on each connection plate, each opening leading into a media channel, with each media opening of the connection plate being arranged to correspond to a media inlet or media outlet on the connection surface of the carrier. For example, two or three media openings can be provided per connection plate, the arrangement of which corresponds to the arrangement of the corresponding media inlets and media outlets on the connection surface of the carrier, so that several fluidic connections can be established via one connection part. This reduces the required installation space. The elastic fastening is preferably achieved via elastic damping elements, such as spring elements or elastic plastic elements, in particular made of an elastomer.

[0014] The elastic damping elements are preferably arranged between the connecting plate and the base body. This allows the connecting plates to be tilted slightly relative to the base body in all axes, reliably compensating for alignment errors or angular inaccuracies with the support's connecting surface. Nevertheless, the implementation of these damping elements is simple and cost-effective.

[0015] A particularly simple design is achieved when the connecting plate is at least indirectly attached to the base body by screws, with the elastic damping elements interposed. Accordingly, the same base body can also be designed for different connection configurations, since the screw connection allows for the exchange of connecting parts.

[0016] In a further embodiment, each screw is surrounded by an elastic damping element. This screw is tightened only enough to ensure the attachment to the base body, while still allowing the connecting surface to the base body to be elastically tilted.

[0017] In an alternative embodiment, an elastic damping element radially surrounding the media channel(s) of the connecting part is arranged between the base body and the connecting plate. The damping element is usually arranged between the rear side of the connecting plate and the surface of the base body or a part attached to the base body. The fastening can be carried out using screws or by means of a material bond, for example, by gluing. Here, too, the tiltability of the connecting plate to the

[0018] Angular misalignment compensation obtained.

[0019] In yet another alternative design, an elastic damping element is arranged radially between the base body and the connecting part in the through-hole of the base body, radially surrounding the media channel(s) of the connecting part. In this design, the connecting part is thus elastically mounted in the through-hole, thus allowing for the compensation of alignment errors. Additional fastening can be completely dispensed with in this design.

[0020] Preferably, a seal is arranged on the surface of the connection plate facing the fuel cell stack. This seal surrounds each individual media channel on the connection plate. The seal is also designed to be elastic, so that even small unevenness or dimensional inaccuracies in the connection surface can be compensated. Furthermore, by firmly tightening the connection surface against the seal, an axial deformation of the seal is achieved, which increases the tightness of the connection.

[0021] It is particularly advantageous if the connecting part consists of the connecting plate and a media guide section extending from the connecting plate through the through-opening of the base body, in which the media channel(s) are formed. This media guide section can also extend through the through-openings in the base body. This media guide section creates the space in which the damping elements can be arranged to compensate for tolerances.

[0022] In addition, the connecting part preferably has a flange plate that is attached to the base body and to which the connecting plate is secured with the interposition of at least one elastic damping element. This allows the entire connecting part, including the damping elements, to be preassembled and then, in particular, force-fitted to the base body. This reduces setup time on the test bench when changing to a carrier with a different connection surface.

[0023] In a further embodiment, the media guide section extends from the connecting plate through the opening in the flange plate. The connecting plate, together with the media guide section, is arranged so that it can be elastically tilted relative to the flange plate.

[0024] To ensure the correct lateral alignment of the carrier, and thus of the connection surface, to the base body and thus to the connection plates, guide pins arranged fixedly to the base body extend toward the connection surface of the carrier. Corresponding pin receptacles are formed on the connection surface, into which the guide pins engage when the carrier rests with its connection surface against the connection plate. These guide pins are preferably slightly conical, so that the lateral alignment correction occurs automatically when the carrier is tightened to the interface unit.

[0025] It is particularly preferred if a tightening device is formed on the base body, via which the carrier can be moved against the connecting plates. The carrier thus only needs to be moved up to the interface unit until the tightening device engages the carrier. The subsequent tightening then achieves alignment via the guide pins. Furthermore, the tightening device can generate a defined contact pressure for a fluid-tight connection. For this purpose, the tightening device has a hydraulic, electromotive, or pneumatic actuator via which it is actuated. These actuators can generate a defined contact pressure.

[0026] In a further embodiment, the tightening device has a driver, via which a positive connection to a driver receptacle on the carrier can be established at least in a direction perpendicular to the connection surface, wherein the driver can be moved in the direction of the base body by means of the actuator after engagement in the driver receptacle, whereby the carrier with its connection surface can be moved against the connection plate. The driver can, for example, be designed as a movable hook, the bent end of which engages behind a correspondingly shaped recess and thus establishes the positive connection in the direction perpendicular to the connection surface of the carrier. This means that a movement in this direction can be initiated by the tightening device due to the positive connection.By pulling in the hook, the carrier and thus the fuel cell stack can then be automatically pulled correctly to the interface unit.

[0027] In a further advantageous embodiment of the invention, an electrical contact unit is additionally formed on the base body, which corresponds to an electrical mating contact unit on the connection surface of the carrier. Thus, by tightening, not only the purely fluidic connection but also the electrical connection can be automatically and correctly established. The electrical contact unit can have contacts for both measurement and electrical supply.

[0028] Thus, by actuating the tightening device, the electrical contact unit can be moved into the electrical counter-contact unit, whereby an electrical connection can be easily established between the interface unit and thus the test unit and the fuel cell stack or the carrier.

[0029] Furthermore, it is advantageous if an additional interface unit can be moved from another side of the carrier against an additional connection surface of the carrier to establish fluidic or electrical connections. This can be done via a robot that docks, for example, to the rear of the fuel cell stack.

[0030] The carrier preferably has a carrier plate on which the fuel cell stack is fastened and to which an adapter plate is fastened, on which the connection surface is formed. The carrier can additionally have wheels for movement. The fuel cell stack is placed on the carrier plate and the internal connections of the fuel cell stack to the adapter plate can be made outside the test bench, allowing complete pre-installation. The adapter plate thus contains the connections to the fuel cell stack on the inside and the connection surface with the media inlets and outlets to the interface unit on the outside. In addition, the adapter plate can have the electrical connections to the fuel cell stack and, accordingly, the electrical mating contact unit.

[0031] In a further embodiment, additional media inlets and / or media outlets and / or electrical contact units are formed on the carrier plate, which can be connected to media lines or electrical contact units. If not all connections can be made via the adapter plate, additional connections can be made via the carrier plate, for example, using a robot.

[0032] This provides a connecting device for connecting a fuel cell stack to a test unit, replacing expensive multi-coupling plates with various integrated couplings and additional setup parts. Almost no setup effort is required on the test bench, and significantly more test cycles can be achieved per shift. Furthermore, no additional setup material is required. In addition, the testing effort, equipment, and setup release time are eliminated, as these are automated and errors are avoided. Pre-setup can be performed almost entirely off-site. Test cycle times are significantly reduced, resulting in higher throughput and thus lower test costs per fuel cell stack.The elastic damping element in the connection area on the test bench compensates for any slight angular misalignment that may occur during automatic docking, thus ensuring a correct and tight connection. Furthermore, the media connections on the fuel cell stack, which are sensitive to mechanical vibrations, are protected by the elastic damping element, as impacts to the fuel cell stack are dampened. In addition to this damping, alignment errors in all directions are prevented and angular inaccuracies are corrected, thus creating a tight connection with adjustable contact pressure.

[0033] An embodiment of a connecting device according to the invention for connecting a fuel cell stack to a test unit is shown in the figures and is described below.

[0034] Figure 1 shows a perspective view of the connecting device according to the invention for connecting a fuel cell stack to a test unit.

[0035] Figure 2 shows a schematic representation of a test system for fuel cells with a connecting device according to the invention. The test system according to the invention consists of a typically stationary test unit 10, which includes an anode gas supply unit 12 and a cathode gas supply unit 14, as well as at least one or more conditioning units 16 for regulating the pressure and temperature of the media gases.

[0036] The anode gas supply unit 12 and the cathode gas supply unit 14 have mass flow regulators, pressure regulating valves and temperature sensors (not shown) in order to be able to supply the anode gas and the cathode gas to a fuel cell stack 18 in a controlled and conditioned manner.

[0037] Correspondingly, several media pipes 20 protrude from the test unit 10, which extend from the test unit 10 to an interface unit 22, which is to be connected to the fuel cell stack 18 and via which the cathode gas and the anode gas can be conducted to the interface unit 22 and thus to the fuel cell stack 18, and from the fuel cell stack 18 via the interface unit 22 back to the test unit 10. Furthermore, the test unit 10 is connected to the interface unit 22 via electrical lines 24.

[0038] The interface unit 22, which is arranged fixedly to the test unit 10 on the test bench, forms the connecting device 28 according to the invention with a movable carrier 26.

[0039] The interface unit 20 consists of a plate-shaped base body 30, in which, in the present embodiment, two through-openings 32 are formed. A media guide section 34 of a connecting part 36 protrudes through each of these through-openings 32. These connecting parts 36 each terminate in the area facing the carrier 26 at a connecting plate 38, in which three media openings 40 are formed, each forming an inlet or outlet of a media channel 42 extending through the connecting part 36 or the media guide section 34. On the side facing the test unit 10, these media channels 42 are connected to the test unit 10 via the media pipes 20.

[0040] The connection parts 36 are attached to the base body 30 in an elastic manner, so that the connection parts 36 can tilt slightly in all directions relative to the permanently installed base body 30.

[0041] This is achieved in that the connecting parts 36 each have a flange plate 44 which has an inner opening 46 that essentially corresponds to the through-opening 32 on the base body 30. This flange plate 44 is screwed to the base body 30 so that the through-opening 32 essentially covers the inner opening 46. The connecting plate 38 with the adjoining media guide section 34 is screwed to this flange plate 44 so that the media guide section 34 extends through the through-opening 32 and the opening 46 in the flange plate 44 to the opposite side of the plate-shaped base body 30. However, this screw connection takes place with the interposition of elastic damping elements 48. In the present exemplary embodiment, the screws 50 with which the connecting plate 38 is fastened to the flange plate 44 are surrounded by these elastic damping elements 48.The connection plate 38 is thus arranged at a distance from the flange plate 44 and can be inclined at least slightly in any direction by elastic deformation of the damping elements 48. The damping elements 48 can be designed as spring elements or elastic plastic elements. Alternatively, for example, a single elastic damping element 48 per connection plate 38 can be arranged between the connection plate 38 and the flange plate 44 or directly between the connection plate 38 and the base body 30. It is also possible to insert an elastic damping element 48 inside between the media guide section 34 and the edge of the through-opening 32, via which elastic damping element 48 the connection part 36 is held elastically in the base body 30.

[0042] On a surface 51 of the connecting plate 38 facing the carrier 26 or the fuel cell stack 18, a seal 52 is additionally arranged, which surrounds each of the three media openings 40. During the test runs, the two connecting plates 38, with these seals 52, rest against a connecting surface 54 of the carrier 26.

[0043] This connection surface 54 is formed on an adapter plate 56 of the carrier 26, on which media inlets 58 and media outlets 60 corresponding to the media openings 40 of the connection plate 38 are formed, which are in fluid communication with the corresponding channels of the fuel cell stack 18. The latter is mounted on a carrier plate 62, which in turn is connected to the adapter plate 56.

[0044] In order for the connection surface 54 of the adapter plate 56 to be moved precisely and with a defined pressure against the connection plate 38 to create a tight connection, a tightening device 64 is attached to the base body 30. The tightening device has an actuator 66, for example in the form of an electric motor, and a driver 68 in the form of a hook that can be moved by means of the actuator 66. The actuator 66 is attached to the side of the base body 30 facing away from the carrier 26, while the driver 68 extends through a further, central opening 70 in the base body 30 towards the adapter plate 56. A driver receptacle 72 is formed on the adapter plate 56, into which a hook end 74 of the driver 68 engages, and which extends from the adapter plate 56 towards the interface unit 22.By actuating the actuator 66, the driver 68 is displaced toward the actuator 66, whereby the carrier 26 with the fuel cell stack 18 is also moved toward the base body 30 until the connection plate 38 rests against the connection surface 54 of the adapter plate 56. The contact pressure to be generated can be adjusted via the actuator 66.

[0045] To ensure that the media openings 40 of the connection plates 38 are aligned as precisely as possible with the media inlets 58 and media outlets 60 of the connection surface 54 during this tightening process, guide pins 76 extend from the interface unit 22 straight in the direction of the connection surface 54. In the present embodiment, these are formed on the tightening device 64 and extend through the opening 46 in the base body 30, but could also extend directly from the base body 30. Corresponding pin receptacles 78 are formed on the adapter plate 56 or on the carrier 26, into which the guide pins 76 are inserted with as much precision as possible when the tightening device 64 pulls the carrier 26 towards the interface unit 22.In order to ensure that the guide pins 76 can be inserted even if the alignment of the carrier 26 to the interface unit 22 is not entirely correct and that a position correction of the carrier 26 to the interface unit 22 takes place when tightening, the guide pins 76 are conical at least at their end pointing towards the adapter plate 56.

[0046] Additionally, an electrical contact unit 80 is formed on the interface unit 22 and is connected to the test unit 10 via the electrical lines 24. A corresponding electrical counter-contact unit 82 is formed on the adapter plate 56, via which, for example, the current generated in the fuel cell stack 18 can be transmitted to the test unit and measured in the test unit 10. When the carrier 26 is tightened by the tightening device 64, an electrical connection is automatically established between the fuel cell stack 18 and / or other electrical components on the carrier 26.

[0047] If a test run is to be performed for a fuel cell stack 18, the fuel cell stack 18 is first attached to the carrier 26 outside the test bench, and the necessary mechanical and electrical connections are made. The carrier 26 with the fuel cell stack 18 is then moved to the test bench and positioned in front of the interface unit 22 such that the connection surface 54 of the carrier 26 is arranged opposite the connection plates 38 of the interface unit 22 and the driver 68 engages the driver receptacle 72. By actuating the actuator 66, the carrier 26 with the fuel cell stack 18 is then pulled toward the interface unit 22, with the driver receptacle 72 being retracted into the opening 70.The guide pins 76 align the media inlets 58 and the media outlets 60 of the adapter plate 56 of the carrier 26, and thus of the fuel cell stack 18, with the media openings 40 of the connection plates 38 of the interface unit 22. Although this ensures reliable lateral and vertical alignment, an angular offset of the connection plates 38 relative to the connection surface 54 can occur, particularly due to manufacturing tolerances. However, this can be compensated for by the elastic fastening of the connection plates 38, since the connection plates 38 can be slightly tilted in all directions relative to the base body 30 and are thus aligned with the connection surface 54.In this way, a very uniform contact pressure can be produced over the entire circumference of the connection plates 38, which leads to a high degree of tightness over the entire circumference of the connection plates 38 and thus also to a tight connection of the media channels 42 to the media inlets 58 and media outlets 60 of the carrier 26. At the same time, the electrical connection of the carrier 26 or the fuel cell stack 18 to the interface unit and thus to the test unit 10 is established.

[0048] Of course, it is also possible to move additional interface units 84 or connections against corresponding connection surfaces of the carrier 26, which are shown only as boxes in Figure 2, from the side of the carrier plate 62 or from the side of the carrier 26 opposite the interface unit 22 by means of an ID robot or a 2D robot.

Claims

PATENT CLAIMS 1. A connecting device for connecting a fuel cell stack (18) to a test unit (10), comprising: - an interface unit (22) connected to the test unit (10) with a base body (30) having at least one through-opening (32), and with at least one connecting part (36) which is fastened to the base body (30) and has a connecting plate (38) in which at least one media opening (40) is formed, which is fluidically connected to a media channel (42), wherein the at least one media channel (42) extends from the media opening (40) facing the fuel cell stack (18) through the connecting plate (38) and the at least one through-opening (32) in the base body (30) to the side of the base body (30) facing away from the fuel cell stack (18), and is connected to the test unit (10) via continuing media pipes (20), - a movable support (26) to which the fuel cell stack (18) is attached and on which a connection surface (54) is formed, on which a plurality of media inlets (58) and media outlets (60) are formed, which are fluidically connected to the fuel cell stack (18), - wherein the carrier (26) is movable with its connection surface (54) against the at least one connection plate (38) of the interface unit (22) or the connection plate (38) of the interface unit (22) is movable against the connection surface (54) of the carrier (26), wherein the at least one media opening (40) of the at least one connection plate (38) corresponds to one of the media inlets (58) and / or media outlets (60) of the connection surface (54) of the carrier (26), so that in the state in which the carrier (26) rests with its connection surface (54) against the connection plate (38), a fluidic connection is established between the media inlet (58) and / or media outlet (60) of the connection surface (54) and the at least one media channel (42) of the connection part (36), wherein the connection plate (38) is at least indirectly elastically fastened to the base body (30).

2. Connecting device for connecting a fuel cell stack (18) to a test unit (10) according to claim 1, characterized in that the interface unit (22) has a plurality of connection plates (38) which are at least indirectly elastically fastened to the base body (30).

3. Connecting device for connecting a fuel cell stack (18) to a test unit (10) according to claim 1 or 2, characterized in that a plurality of media openings (40) are formed on each connecting plate (38), each opening into a media channel (42), wherein each media opening (40) of the connecting plate (38) is arranged to correspond to a media inlet (58) or media outlet (60) on the connecting surface (54) of the carrier (26).

4. Connecting device for connecting a fuel cell stack (18) to a test unit (10) according to one of the preceding claims, characterized in that the elastic fastening is effected via elastic damping elements (48) which are designed as spring elements or elastic plastic elements.

5. Connecting device for connecting a fuel cell stack (18) with a test unit (10) according to one of the preceding claims, characterized in that the elastic damping elements (48) are arranged between the connecting plate (38) and the base body (30).

6. Connecting device for connecting a fuel cell stack (18) to a test unit (10) according to claim 5, characterized in that the connecting plate (38) is fastened at least indirectly to the base body (30) by screws (50) with the elastic damping elements (48) interposed.

7. Connecting device for connecting a fuel cell stack (18) to a test unit (10) according to claim 6, characterized in that each screw (50) is surrounded by an elastic damping element (48).

8. Connecting device for connecting a fuel cell stack (18) to a test unit (10) according to one of claims 4 to 6, characterized in that an elastic damping element (48) radially surrounding the media channel(s) (42) of the connecting part (36) is arranged between the base body (30) and the connecting plate (38).

9. Connecting device for connecting a fuel cell stack (18) to a test unit (10) according to claim 4, characterized in that an elastic damping element (48) radially surrounding the media channel(s) (42) of the connecting part (36) is arranged radially between the base body (30) and the connecting part (36) in the through-opening (32) of the base body (30).

10. Connecting device for connecting a fuel cell stack (18) to a test unit (10) according to one of the preceding claims, characterized in that a seal (52) is arranged on the surface (51) of the connection plate (38) facing the fuel cell stack (18) or on the connection surface (54) of the carrier (26).

11. Connecting device for connecting a fuel cell stack (18) to a test unit (10) according to one of the preceding claims, characterized in that the connecting part (36) consists of the connecting plate (38) and a media guide section (34) extending from the connecting plate (38) through the through-opening (32) of the base body (30), in which the media channel(s) (42) are formed.

12. Connecting device for connecting a fuel cell stack (18) to a test unit (10) according to one of the preceding claims, characterized in that the connecting part (36) has a flange plate (44) which is fastened to the base body (30) and to which the connecting plate (38) is fastened with the interposition of the at least one elastic damping element (48).

13. Connecting device for connecting a fuel cell stack (18) to a test unit (10) according to claim 12, characterized in that the media guide section (34) extends from the connection plate (38) through an opening (46) of the flange plate (44).

14. Connecting device for connecting a fuel cell stack (18) to a test unit (10) according to one of the preceding claims, characterized in that guide pins (76) arranged fixedly to the base body (30) extend in the direction of the connection surface (54) of the carrier (26) and corresponding pin receptacles (78) are formed on the connection surface (54), into which the guide pins (76) engage in the state in which the carrier (26) rests with its connection surface (54) against the connection plate (38).

15. Connecting device for connecting a fuel cell stack (18) to a test unit (10) according to one of the preceding claims, characterized in that a tightening device (64) is formed on the base body (30), via which the carrier (26) can be moved against the connection plates (38).

16. Connecting device for connecting a fuel cell stack (18) to a test unit (10) according to claim 15, characterized in that the tightening device (64) has a hydraulic, electromotive or pneumatic actuator (66).

17. Connecting device for connecting a fuel cell stack (18) to a test unit (10) according to claim 16, characterized in that the tightening device (64) has a driver (68) via which a positive connection to a driver receptacle (72) on the carrier (26) can be produced at least in a direction perpendicular to the connection surface (54), wherein the driver (68) after engagement in the driver receptacle (72) by means of the actuator (66) in the direction is movable relative to the base body (30), whereby the carrier (26) with its connecting surface (54) can be moved against the connecting plate (38).

18. Connecting device for connecting a fuel cell stack (18) to a test unit (10) according to one of the preceding claims, characterized in that an electrical contact unit (80) is formed on the base body (30), which corresponds to an electrical counter-contact unit (82) on the connection surface (54) of the carrier (26).

19. Connecting device for connecting a fuel cell stack (18) to a test unit (10) according to claim 18, characterized in that by actuating the tightening device (64) the electrical counter-contact unit (82) can be moved into the electrical contact unit (80).

20. Connecting device for connecting a fuel cell stack (18) to a test unit (10) according to one of the preceding claims, characterized in that an additional interface unit (84) can be moved from another side of the carrier (26) against an additional connection surface (54) of the carrier (26) for establishing fluidic or electrical connections.

21. Connecting device for connecting a fuel cell stack (18) to a test unit (10) according to one of the preceding claims, characterized in that the carrier (26) has a carrier plate (62) on which the fuel cell stack (18) is fastened and to which an adapter plate (56) is fastened, on which the connection surface (54) is formed.

22. Connecting device for connecting a fuel cell stack (18) to a test unit (10) according to claim 21, characterized in that additional media inlets and / or media outlets are formed on the carrier plate (62), which can be connected to media lines.

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