WO2021170732A1

WO2021170732A1 - Method for aligning thin-film elements, and device

Info

Publication number: WO2021170732A1
Application number: PCT/EP2021/054713
Authority: WO
Inventors: Andreas Walter; Joachim Benkenstein; Holger Stanik
Original assignee: Thyssenkrupp System Engineering Gmbh; Thyssenkrupp Ag
Priority date: 2020-02-26
Filing date: 2021-02-25
Publication date: 2021-09-02
Also published as: DE102020202480B4; EP4111519A1; DE102020202480A1

Abstract

The invention relates to a device for mutually aligning two thin-film elements, in particular fuel-cell stack elements, in the correct position, said device comprising a component-receiving portion for receiving two thin-film elements with different designs, in a vertical stack one above the other.

Description

Method for aligning thin-film elements and device

The invention relates to a method for positionally accurate and mutual alignment of two thin-film elements, in particular fuel cell rod elements, with a construction part mount for vertically stacked mounting of two thin-film elements with different properties, and a device.

In simplified terms, a fuel cell rod consists of several individual fuel cells stacked one on top of the other, an upper cover plate and a lower cover plate. A fuel cell stick is referred to in English with the term “stack”. Membrane-electrode units - abbreviated MEA - and bipolar plates - abbreviated BPP - are stacked alternately between the upper and lower cover plates. The process of stacking is expediently carried out in the vertical direction; A horizontal juxtaposition of BPP and MEA is also conceivable. The number of stacked fuel cells depends on the output of the “stack” to be achieved and can be in the order of 600 parts with a height of around 680 mm. The MEA and the BPP are of different types, which is expressed in particular in the fact that the MEA is very pliable or flexible and the BPP, in contrast, has a much higher flexural rigidity, which is due to the fact that the BPP is made of a metallic material exists and is usually thicker than the MEA. Alternatively, a BPP can also be made from a graphite-like material and the MEA from a silicone-like material.

The production of fuel cell stacks can conventionally be carried out using two different processes. On the one hand, stacking, pressing and subsequent tension element assembly can take place in one device. The fuel cell stack is then removed from the device and transported to the remaining assembly. On the other hand, the fuel cell stacks can be stacked in one device. The fuel cell stacks are then transferred to a press that is attached to a handling device such as a robot. The stacks, including the press, are then passed on to a device for the assembly of tension elements. Then the transport takes place in the remainder of the month. In both processes, the BPP and the MEA are stacked alternately until the required “stack” height is reached. Every time the MEA is handled, it is necessary to observe its low inherent stability in order not to damage it. In addition, when stacking the MEA on the BPP, or optionally vice versa, both of them must be brought into a reference position to one another. Both the MEA and the BPP are flat. The width and length of the MEA is greater than the corresponding width and length of the BPP. The reference position from MEA to BPP is reached when the MEA is in a defined th position is positioned opposite the face of the BPP. As a rule, BPP and MEA have a common reference edge that is placed next to one another so that BPP and this reference edge are aligned in pairs. In summary, the stacking of MEA and BPP to form the “stack” and the simultaneous alignment of the MEA and the BPP in reference position to one another requires a comparatively high level of equipment and process engineering effort, which runs counter to the overriding goals of increasing the number of items with a simultaneous reduction in cycle times. Against this background, it would be desirable to simplify the conventionally integrated but technically complex stacking process and to subdivide it into individual sub-processes in order to then be able to carry out each individual process with simplified means.

Based on this, the object of the present invention is to provide a simplified sub-process for aligning MEA to BPP in the reference position to one another in the sense of what has been described above.

The object is achieved by a method for positionally accurate and mutual alignment of two thin-film elements, in particular fuel cell rod elements, in which two thin-film elements with different properties are stacked vertically on top of one another, the first thin-film element, which is provided with a greater flexural strength than the second thin-film element, via a device-side provided Ansaugele element is brought into a starting position, the second thin-film element is held in a floating position relative to the first thin-film element by means of a blowing device provided on the device side, the first and second thin-film elements are brought into a reference position relative to one another by positioning elements provided on the device side, and the first and the second second thin-film element are adhesively connected to one another in the reference position.

The basic idea of the method according to the invention is that first of all the main process of stacking is separated from the part process of precisely positioned and mutual alignment of two thin-film elements, or the stacking elements MEA and BPP, and then the alignment is carried out as a separate and self-sufficient process. This alignment process can then take place within the required tolerances and quality requirements. According to the invention it is provided that the MEA and the BPP, after they have been brought into the reference position to one another, are adhesively connected to each other at least for the period of time until both are stacked as a connected unit in the plaupting process. A connection that extends beyond this time is usually not absolutely necessary, but it can certainly be provided. By connecting the MEA to the BPP in this separate process according to the invention, the low flexural rigidity and flexibility of the MEA no longer plays a role in the subsequent stacking process, it can only be limited to gripping or handling the BPP, which allows significantly less effort. This simplifies the stacking process. Due to the manufacturing process, a BPP has a minimal curvature that would be a hindrance in the later “stack”, so that the method according to the invention achieves that the thin-film element with the greater flexural rigidity, i.e. the BPP in this case, is held in the starting position via the suction element that the initial curvature is equalized.

An advantageous embodiment of the method provides that the first and second thin-film elements are brought into the reference position via mutual alignment by the positioning elements. This ensures that the respective movement of each individual thin-film element can be smaller, so that the risk of damage is reduced. In a specific embodiment of the method, the first and second thin-film elements are brought into the reference position via mutual alignment by the positioning elements.

An advantageous embodiment of the method provides that after the floating position of the second thin-film element has been resolved, the first and the second thin-film element are adhesively connected to one another in the reference position. It can either be provided that the floating state is dissolved over the entire surface of the second thin-film element, which is preferably achieved by terminating the function of the blowing device, or the floating position is released by opposing, punctiform pressing of the two thin-film elements against one another.

The object is also achieved by a device for the positionally accurate and mutual alignment of two thin-film elements, in particular fuel cell rod elements, with a component holder for holding two thin-film elements of different types stacked vertically on top of each other, a suction element for causing an air flow to be drawn in in a substantially vertical one Direction in the area of the construction part recording, for exerting a vertical force on one of the thin-film elements via the air flow sucked in, a blowing device for causing a blown air flow in the area of the component recording, for exerting a vertical force of the other of the thin-film elements by means of the blown air flow, positioning elements, the are movable between an initial position and a horizontally delivered position against each other in order to be in the delivered position with the two thin-film elements in a Wi rkverbin tion to stand and to hold the two thin-film elements in a reference position to each other and an adhesion device for the adhesive connection of the first and second thin-film elements located in the reference position to each other. The basic idea of the device according to the invention is to initially receive or hold the two thin-film elements in a stacked manner, then to transfer them to a position in which almost forceless movement in space is possible, in order to then move into the reference position to undertake. By connecting the MEA and BPP, these elements are each prepared as a unit for later stacking, so that the cycle time for the actual stacking can be reduced. Halving the cycle time is possible. The softer, more pliable MEA is connected to the BPP, so that the actual stacking can only take place by handling the BPP. The device allows the alignment process to be carried out in a dedicated manner without further boundary conditions, so that the alignment accuracy between BPP and MEA can be increased compared to the conventional integrated stacking process.

In a preferred embodiment, the adhesion device has at least one laser welding unit. Using the laser welding units, several connection points can be set over the scope of the BPP and MEA as required and precisely positioned, which hold the BPP and MEA against each other. It can be sufficient here if these connection points only form a temporary connection between the BPP and MEA, which connection lasts at least until the BPP and MEA are processed in the stacking process. The connection between BPP and MEA is therefore preferably an adhesion between the two elements and not a material connection, which of course can also be provided for certain areas of application. It is also conceivable to establish the adhesion between BPP and MEA via water or a water-soluble medium.

In a preferred embodiment, several laser welding units are arranged along a circumference in the area of the component receptacle. It is thus possible to establish all connection points between MEA and BPP synchronously.

In a preferred embodiment, an acted upon pressure unit is provided in order to bring about a vertically directed pressure force on the two thin-film elements against the component receptacle. This makes it possible to act on the BPP and the MEA directly starting from the floating state of the MEA against the BPP in order to then undertake the adhesion.

In a preferred embodiment, the component receptacle is mounted in a floating manner with respect to a frame element of the device. It can be provided here that an alignment unit of the device can be advanced in a stamp-like manner with respect to the component receptacle.

With regard to the blowing device, two configurations are conceivable. In the first embodiment, the blowing device has two blowing nozzles arranged in the same vertical position, wherein the blower nozzles blow essentially horizontally into the region of the component receptacle from opposite directions during operation. In the second embodiment, the blowing device is integrated into the component receptacle in such a way that a floor area for accommodating the thin-film elements is air-permeable in order to blow the respective thin-film element with the air flow generated by the blowing device and passed through the floor area.

The invention is explained below with further features, details and advantages on the basis of the accompanying figures. The figures illustrate only exemplary embodiments of the invention. Show in it

FIG. 1 an alignment device according to the invention in a starting position;

FIGS. 2 to 4 show the alignment device according to FIG. 1 in further positions and FIG. 5 shows a detail of the alignment device according to FIG. 1.

FIG. 1 shows a possible embodiment of a device 10 according to the invention for the precise positioning and mutual alignment of two fuel cell rod elements, which can be designed, for example, as an MEA and as a BPP. In the present case, the device is not intended to be described in its entirety and in all details. Rather, only essential components and their interaction are to be described.

The device initially has a frame element 44, which can also be referred to as a base plate, and which, among other things, carries the adhesion device 50 with a plurality of laser welding units 52. A hold-down frame 46 is arranged below the frame element 44 and can be moved vertically opposite or on the frame element 44 in a suitable manner. The hold-down frame 46 comprises a pressing unit 42, which in turn forms a plurality of resiliently mounted pressing rams 48. On the frame element 44, a Ausrichtrah menelement 54 is arranged below, which can also be moved vertically opposite or on the frame element 44 in a suitable manner and thus also be able to perform a relative movement with respect to the hold-down frame 46. The alignment frame element 54 comprises positioning elements 40 and a pneumatic unit, which in the present case comprises a suction element 20 and a blowing device 30.

As the lowest component, the device has a component receptacle 12, which is designed to receive the fuel cell rod elements, that is to say the BPP and the MEA, in a stacked manner. The component holder 12 is made in two parts and comprises a floating section. The component receptacle 12 can be designed like a drawer in relation to the other components of the device, so that they can be moved out in a horizontal plane can. The component receptacle 12 also has counter-holder elements 56 as counterparts for the pressure rams 48 of the hold-down frame 46.

FIG. 1 shows the device 10 in a basic position in which the hold-down frame 46 and the alignment frame element 54 are in the vertically upper position. In this position, the component holder 12 can move out laterally like a drawer and then retract it again. The extended position is intended to equip the component holder with fuel cell rod elements, that is to say the BPP and the MEA, in this position. In the basic position, the positioning elements 40 are in a starting position in which they are moved apart in a horizontal direction. If the floating section of the component receptacle 12 is equipped with the BPP and the MEA, then the BPP and MEA are pre-aligned between the lateral and frontal boundaries in such a way that the positioning elements 40 can engage in specially provided grooves of the BPP and the MEA during later alignment nen.

FIG. 2 shows a position of the device 10 in which the hold-down frame 46 and the alignment frame element 54 have been moved vertically downwards via a suitably designed drive of the frame element 44. During the vertical downward movement, the alignment frame element 54 hits a stop so that it is aligned in the vertical direction with respect to the component receptacle 12. Alignment pins on the alignment frame element 54 align the component receptacle 12 together with the resilient pressure plungers 48 with respect to the frame element 44 when it is lowered. In this position, which can be characterized as a storage position, the positioning elements 40, the suction element 20 and the blowing device 30 are delivered in the required position. It can be provided here that the suction element 20 and the blowing device 30 are made ready for operation when the storage position is reached.

FIG. 3 shows a position of the device 10 in which the hold-down frame element 46 has been moved further downward in the vertical direction. In this position, the actual alignment of the BPP and the MEA with one another can take place. For this purpose, the BPP is gripped via the suction element 20 or held in a sucked-in position and pulled upward in the vertical direction against the counter-holder elements 56. As a result, any design-related bending of the BPP is pulled straight and a small gap is created between the raised BPP and the component holder 12. The suction force of the suction element 20 is so low that the BPP is nevertheless in the horizontal plane of the component holder 12, i.e. in X and Y direction, can be moved during the later alignment process. Within this gap between the BPP and the component holder 12, the MEA now goes into a floating state or a floating position as a result of the blowing off of the blowing device 30, so that a Partial gap between BPP and MEA and a partial gap between MEA and component holder 12 is created. If this state of the sucked-in BPP and the MEA held in the floating position is reached, the positioning elements 40 are actuated via suitable actuators, so that the BPP and the MEA are aligned with one another in the reference position.

FIG. 4 shows a position of the device 10 in which the positioning elements 40 have been advanced against one another in a horizontal direction, so that the BPP and the MEA are in the reference position to one another and assume a defined position with respect to the component receptacle 12. In this state, the resilient pressure stamps 48 come into contact with the BPP and the BPP and the MEA are pressed against the counter-holder element 56 of the component receptacle 12 without a gap, at least in the area of the contact areas. After reaching this contacting position, all elements are aligned with one another and have a gap-free contact and the BPP can be adhesively connected to the MEA, which in the present case takes place via the laser welding units 52.

FIG. 5 shows a detailed view of the component receptacle 12 and a section of the alignment frame element 54 with the suction element 20 and the blowing device 30 of the pneumatic unit. The BPP and the MEA can be seen, which are positioned on the component receptacle 12 and, as described above, form air gaps to one another due to the function of the suction element 20 and the blowing device 30. The air flow blown off by the blowing device 30 is symbolized by the reference numeral 32. For this purpose, the blowing device 30 has two blowing nozzles 34 arranged in the same vertical position, the blowing nozzles 34 blowing horizontally into the region of the component holder 12 from opposite directions during operation. The MEA is placed in a state of suspension in the vertical direction by the two opposite blowing nozzles 34. In this floating state, the MEA can be moved or positioned in the horizontal plane with an extremely low expenditure of force, ie without friction. In its state sucked in by the suction element 20, the BPP can also be moved or positioned in the horizontal plane with little effort. After reaching the respective correct position of the MEA and the BPP in the horizontal plane, the BPP and MEA are in the reference position to each other and are brought into gap-free contact with the pressure unit 48 and its pressure stamp 48 and the counter-holder elements 56. The BP and MEA can then be connected to one another with the laser welding units 52. List of reference symbols

2 thin film element

4 thin film element

10 alignment device

12 Component holder

14 floor area

20 suction element

30 blowing device

32 airflow

34 air nozzles

40 positioning element

42 pressure unit

44 frame element

46 Hold-down frame

48 pressure stamp

50 adhesion device

52 laser welding unit

54 alignment frame element

56 Counterholder element

Claims

1. A method for the positionally accurate and mutual alignment of two thin-film elements (2, 4), in particular of fuel cell rod elements, in which two thin-film elements (2, 4) of different properties are stacked vertically on top of one another, with a greater flexural strength than the second thin-film element (2, 4) equipped first thin-film element (2) is brought into a starting position via a suction gel element (20) provided on the device side, the second thin-film element (2) via a blowing device (2) provided on the device side opposite the first thin-film element (4) in is held in a floating position, the first and the second thin-film element (4) are brought into a reference position to one another via positioning elements (40) provided on the device side and the first and the second thin-film element (2, 4) are adhesively connected to one another in the reference position.

2. The method according to claim 1, wherein the first and the second thin-film element are brought into the reference position via mutual alignment by the positioning elements (40).

3. The method as claimed in claim 1 or 2, in which, after the floating position of the second thin-film element (4) has been resolved, the first and second thin-film elements (2, 4) are adhesively connected to one another in the reference position.

4. The method according to claim 3, in which the floating position is resolved by pressing the two thin-film elements (2, 4) against one another at specific points in opposite directions.

5. Device (10) for the positionally accurate and mutual alignment of two thin-film elements (2, 4), in particular of fuel cell rod elements, comprising a component holder (12) for holding two thin-film elements (2, 4), which are stacked vertically, one on top of the other Suction element (20) for bringing about a sucked-in air flow in an essentially vertical direction in the area of the component holder (12), for exerting a vertical force on one of the thin-film elements (2, 4) via the sucked-in air flow, a blowing device (30) for producing a blown air flow in the area of the component receptacle (12), for exerting a vertical force on the other of the thin-film elements (2, 4) by means of the blown air flow,

Positioning elements (40), which are movable between a starting position and a horizontally delivered position against each other, in order to be in operative connection with the two thin-film elements (2, 4) in the delivered position and the two thin-film elements (2, 4) in to hold a reference position to one another and an adhesion device (50) for the adhesive connection of the first and second thin-film elements (2, 4) located in the reference position to one another.

6. Device (10) according to claim 5, characterized in that the Adhäsionsvorrich device (50) comprises at least one laser welding unit (52).

7. The device (10) according to claim 6, characterized in that a plurality of laser welding units (52) are arranged along a circumference in the region of the component receptacle (12).

8. Device (10) according to one of claims 5 to 7, characterized in that an acted upon pressure unit (42) is provided in order to be a vertically directed pressure force on the two thin-film elements (2, 4) against the component holder (12) works.

9. Device (10) according to one of claims 5 to 8, characterized in that the component receptacle (12) is mounted floating relative to a frame element (44) of the device.

10. Device (10) according to one of claims 5 to 9, characterized in that an alignment unit (46) is provided, which can be advanced in a stamp-like manner with respect to the component receptacle (12).

11. The device (10) according to any one of claims 5 to 10, characterized in that the blowing device (30) has two blow nozzles (34) arranged in the same vertical position, the blow nozzles (34) essentially in operation from opposite directions horizontally in the Blow off the area of the component holder (12).

12. Device (12) according to one of claims 5 to 10, characterized in that the blowing device (30) is integrated into the component holder (12) in such a way that a bottom area (14) of the component holder (12) for receiving the thin-film elements ( 2, 4) is made air-permeable in order to match that generated by the blowing device (30) and through the floor area (2, 4) passed air flow to blow the respective thin-layer element (2, 4).