Patent ID: 12212028

DETAILED DESCRIPTION

In the following same or similar functioning elements are indicated with the same reference numerals.

FIG.1shows a perspective view of a manufacturing arrangement1for manufacturing a fuel cell stack2by stacking a plurality of assembled fuel cell units4. As illustrated, the manufacturing arrangement comprises a first alignment station6and a second alignment station8. In the illustrated embodiment, there are two manipulating devices10and12, which are adapted to handle the fuel cell elements. The manufacturing arrangement1further comprises a fastening station14and a handling device16for transferring the fuel cell elements from the alignment station6to the fastening station14. The handling device16of the embodiment shown inFIG.1is a rotatable table.

As is further depicted inFIG.1, the fastening station14comprises a welding manipulator18, which is adapted to fasten or weld a membrane electrode assembly26to a bipolar plate22. Further, the manufacturing arrangement1comprise an aligning manipulator20for aligning the membrane electrode assembly26to the bipolar plate22.

In the following the operation of the manufacturing arrangement1will be described. In a first step, the handling manipulator10transfers a bipolar plate22to a first alignment structure24, e.g. a fixture, which is arranged on the rotating table16. Then the table16is rotated so that the bipolar plate22which is arranged in the alignment structure24is transported to the first alignment station6, where the aligning manipulator20places a membrane electrode assembly (MEA)26on one side of the bipolar plate22, i.e. in the illustrated embodiment ofFIG.1on top of the bipolar plate22. However, it is also possible that the MEA is placed underneath the bipolar plate and/or the first alignment structure is arranged subsequently to the second alignment structure.

The aligning of the MEA26on one side of the bipolar plate22may be performed by any suitable alignment method, regardless whether the MEA or the bipolar plate are handled first. For example, it is possible that the aligning manipulator20comprises a camera, which serves as second aligning structure and determines the position of the bipolar plate22, and based on the determined position, the manipulator orientates/places the MEA26on the bipolar plate. Alternatively or additionally, it is also possible that there is a mechanical second alignment structure, which provides a predetermined spatial orientation for the MEA26in relation to the bipolar plate22, when the MEA26is placed on top of the bipolar plate22. Of course, any other alignment procedure is also possible.

After the MEA26is placed on top of the bipolar plate22, a so-called pre-assembly fuel cell unit28is provided, which is transferred to the fastening station14by means of the rotating table16. At the fastening station14, the MEA26is fastened to the bipolar plate22. This fastening may be done by ultrasonic welding, but any other suitable fastening method may be used, such as gluing, heat combining of thermoplastics, soldering etc. However, ultrasonic welding provides a fast and cheap fastening method, for which no added or special material is needed.

After the fastening station14, the spatial orientation of the MEA26to the bipolar plate22is fixed, so that the now assembled fuel cell unit4, may be removed from the first aligning station for further processing.

In the illustrated embodiment, the assembled fuel cell unit4is removed from the rotating table16by means of the second handling manipulator12and transported to the second alignment station8(stacking). It should be noted that, it is not necessary that the second alignment station8is arranged in close proximity to the first alignment station6. Since the spatial orientation of MEA26and bipolar plate22is fixed due to the fastening step, the assembled fuel cell unit4may be transported to a remote location for the stacking process. It is also possible to put the assembled fuel cell units4on stock and perform the stacking process later on.

However, in the depicted embodiment ofFIG.1, the second alignment station8is arranged in close proximity to the first alignment station so that the assembled fuel cell units4may be transferred directly to the third alignment structure30, which is adapted to align the fuel cell units4to provide the fuel cell stack2. Thereby, the third alignment structure30may be adapted to align the periphery of the fuel cell units4, only, which allows for a fast but precise arrangement of the fuel cell units4. This is due to the fact that the spatial orientation of bipolar plate22and MEA26is fixed by fasting the MEA26to the bipolar plate22.

Consequently, this allows for a fuel cell unit design in which the MEA26overlaps the bipolar plate22in at least one region34(seeFIG.2), wherein this region34is used for aligning the fuel cell units4. This also ensures, that any contact of the third alignment structure with the bipolar plate may be avoided. Further, it is possible to provide a fuel cell unit design, in which the MEA26overlaps the bipolar plate22everywhere. In this embodiment, the third alignment structure30is adapted to align the fuel cell units4solely based on the periphery of the MEA26. Thereby, a fuel cell stack2may be provided in which the risk of a short circuit resulting from contacting adjacent bipolar plates22may be avoided as the membrane of the MEA26reliably isolates the adjacent bipolar plates22.

FIG.2depicts, in a detailed view, the assembled fuel cell unit4having a bipolar plate22and a MEA26, which are fastened together by an ultrasonic weld seam32. It can be further seen that the MEA26overlaps the bipolar plate22in at least the region34, so that only the MEA26contacts the third alignment structure30.

It is further advantageous that the bipolar plate22remains untouched by any device during the alignment of the fuel cell units of the fuel cell stack, which allows for a quick but precise alignment of the fuel cell units.

FIG.3illustrates a further embodiment of the manufacturing arrangement1. As can be seen, in the alternative embodiment aligning and fastening are performed at a combined assembling station36, where two manipulator arms38and40are handling, aligning and fastening the bipolar plates22and the MEA26for providing the assembled fuel cell unit4. In contrast to the manufacturing arrangement ofFIG.1, there is no rotating table, so the risk of misaligning the bipolar plate22and MEA26due to the rotating movement of the table is reduced.

After the fastening, the assembled fuel cell unit4is transferred to the second alignment station8comprising the alignment structure30for stacking the fuel cell units4to the fuel cell stack2.

By separating the alignment of the individual fuel cell elements and the stacking of the fuel cell units into at least two different steps or stations, the alignment and stacking process may be accelerated and automated. Further, by fastening the MEA to the bipolar plate at the fastening station and in the fastening step, respectively, the spatial orientation of the fuel cell elements may be preserved. This in turn allows for a fuel cell unit design in which the MEA overlaps the bipolar plate, and allows equally for a fast and precise stacking process, as the stacking (or second aligning) may be performed based on the orientation of the MEA only. The spatial orientation of the bipolar plate itself can thus be disregarded, as it is already defined by the orientation of the MEA. It is further advantageous that by placing the MEA on one side of the bipolar plate and handling in the further steps the MEA only, the bipolar plate does not need to be contacted in the further assembling process, which ensures a quick and precise stacking procedure.

REFERENCE NUMERALS

1manufacturing arrangement2fuel cell stack4fuel cell unit6first alignment station8second alignment station10,12handling device14fasting station16rotating table18fasting manipulator20aligning manipulator22bipolar plate24first alignment structure26membrane electrode assembly (MEA)28preassembled fuel cell unit30third alignment structure32weld seam34region where MEA extends over bipolar plate36combined assembling station38,40manipulator arms