Contact assembly of bipolar plates and method for contacting bipolar plates

Abstract

The invention relates to a contact assembly of a bipolar plate, comprising two half sheets (2, 3) which are spaced apart parallel to one another and can be attributed to a bipolar plate (10), wherein each half sheet (2, 3) has an embossed element (4, 5) and the embossed elements (4, 5) of the two half sheets (2, 3) face one another, and wherein a connecting pin (6) inserted between the half sheets (2, 3) is in contact with the embossed elements (4, 5) of the half sheets (2, 3).

Description

Technical Field

[0001] This invention relates to contact assemblies for bipolar plates, which are particularly useful in fuel cells. The invention also relates to methods for contacting bipolar plates. Background Technology

[0002] A fuel cell bipolar plate is known from EP 1 900 052 B1, which has a socket for a measurement connector. The bipolar plate comprises two half-sheets connected together, referred to as a cathode bipolar half-plate and an anode bipolar half-plate. Each half-sheet includes a central active region and a circumferential portion with multiple cutouts. Furthermore, a socket, referred to as a hollow receiving portion, is provided on the circumferential portion of the bipolar plate, into which a pin-shaped electrical connection element can be inserted for measurement purposes. The socket is formed by two opposing ribs, each of which is located within the half-sheet.

[0003] WO 2008 / 145 221 A1 discloses a single fuel cell for a fuel cell stack. A nickel mesh is positioned inside the single fuel cell as an electrical contact element. Additionally, the use of a paste made of metallic and ceramic materials as a contact element is proposed.

[0004] DE 10 2018 213 688 A1 discloses a connector comprising a plurality of contact elements for a bipolar stack. Each contact element has a contact body extending along a longitudinal axis, by means of which a channel is formed for receiving a portion of a bipolar plate. A contact spring protrudes into the channel and contacts the bipolar plate. Furthermore, cut edges are provided that cut into the surface of the bipolar plate to ensure a firm contact, which is also intended to withstand vibration and shock loads.

[0005] DE 20 2005 019 195 U1 describes an interface board having circuitry for connection to a fuel cell. The interface board includes a printed circuit board with multiple interfaces that are respectively connected to the fuel cell and an electrical device, wherein the electrical device may be a test apparatus for testing the fuel cell.

[0006] Contact devices that can be used in the testing and monitoring of fuel cells are also known from documents WO 2014 / 060 727 A1, WO 2018 / 236 266 A1, WO 2013 / 041 869 A1 and WO2005 / 069 026 A1. Summary of the Invention

[0007] The problem addressed by this invention is that, compared with the prior art described above, particularly in terms of reasonable manufacturing and low installation space requirements, it provides further development options for contact with bipolar plates, wherein the reliability of the electrical connection is compromised as little as possible.

[0008] According to the present invention, this problem is solved by a contact assembly of a bipolar plate having the following characteristics. Similarly, this problem is solved by the following method for contacting the bipolar plate. The embodiments and advantages of the present invention described below in conjunction with the contact method are applied, with necessary modifications, to the device, i.e., the contact assembly, and the bipolar plate including such an assembly, and vice versa.

[0009] The contact assembly comprises two half-sheets spaced parallel to each other and belonging to a bipolar plate. Each half-sheet has an embossing element, and the embossing elements of the two half-sheets face each other. A connecting pin, also referred to simply as a contact element or pin, is inserted between the half-sheets and contacts the embossing element of the half-sheet. Specifically, the contact assembly can be designed such that the connecting pin contacts only the embossing element of the half-sheet and not the flat area of ​​the half-sheet outside the embossing element.

[0010] The embossing element of one or both halves of the bipolar sheet is specifically designed as a protrusion and can each be a portion of a larger protruding region. This protruding region can serve to guide fluid along the surface of the bipolar plate and simultaneously mechanically stabilize the bipolar plate. Similarly, variations of the bipolar plate can be implemented where no other protrusions exist besides those belonging to the contact assembly. In any case, a small distance between the parallel halves of the sheet is sufficient for the bonding of the contact assembly.

[0011] Because the distance between the bipolar plates of a fuel cell arranged in a stack is not perfectly constant and deviations from the nominal value of the distance can increase, the conceivable wiring strips extending across multiple bipolar plates in the stack may not precisely match the actual geometry of the stack in a mass-produced fuel cell stack in every case. The contact assembly according to this application avoids this problem because it is designed to contact only the two halves of the sheet that can be attributed to a single bipolar plate.

[0012] According to various possible implementations, the embossing elements of one half of the sheet belonging to the contact assembly are arranged offset relative to at least one embossing element of the other half of the sheet also belonging to the contact assembly, wherein the half of the sheet is viewed in a top view. Here, one half of the sheet has the task of laterally guiding the pin, for which at least two embossing elements are required.

[0013] Further improvements to the contact elements are possible in variations of the contact assembly, in which the connecting pin contacts four embossed elements of a first half-sheet and simultaneously contacts a single embossed element of a second half-sheet. The four embossed elements of the first half-sheet are arranged in a rectangular pattern and formed as protrusions, while the single embossed element of the second half-sheet is formed as a recess. In this respect, in each case, the connecting pin can be tangent to the rectangularly arranged protrusions of a sheet in a lateral region of the protrusions, the lateral region of the protrusions being positioned at an angle of at least 5° and at most 60°, particularly at an angle of 45° ± 15°, relative to the plane on which the half-sheets are arranged. Instead of a rectangular arrangement of the protrusions of a half-sheet, for example, a trapezoidal arrangement of these protrusions can also be used.

[0014] In addition to the lateral regions, i.e., the bevels, of the four protrusions on one of the two sheets, the connecting pin also contacts a recess in the other sheet, wherein the recess—again, in the top view of the sheet—may be arranged within a rectangle defined by the four protrusions of the first half-sheet. Specifically, the recess may be located at the center of the rectangle. In particular, the recess is formed to be mirror-symmetrical with respect to a central plane that passes longitudinally through the pin and intersects the two half-sheets orthogonally.

[0015] Regarding the elasticity within the contact assembly, various possibilities exist: on the one hand, the contact element can be designed as a spring-like tongue. If this spring-like tongue is inserted between the half-sheets during assembly, it will at least slightly bend. Similarly, the elastic mounting of the contact element between the half-sheets can be achieved by designing the embossed element of at least one half-sheet as an elastic abutment of a connecting pin, wherein the contact element in this case can be an inherently rigid pin. In particular, this variation, in which the spring action present within the force-fit contact assembly is provided solely by the embossed half-sheet, is characterized by the fact that the pin is always arranged parallel to the plane given by the half-sheet, regardless of the force acting perpendicular to the pin.

[0016] Regardless of the extent of the spring action exerted by the half-sheets and / or contact elements, the imprinted elements of the two half-sheets can be at least approximately dome-shaped. During the assembly of the contact assembly, the contact element is inserted between the half-sheets such that it contacts a plurality of imprinted elements of the half-sheets, particularly a plurality of dome-shaped imprinted elements. The contact element may initially be placed on one half-sheet and thereby laterally guided by the plurality of imprinted elements of that half-sheet. Only in a further step of the contact method is the contact element loaded by a single imprinted element of the second half-sheet. In this method, there is no further contact between the connecting pin and the second half-sheet at any time. No connector housing is provided.

[0017] Contact components are particularly well-suited for performing voltage measurements on bipolar plates. This means that the individual voltages of each cell in a fuel cell stack can be monitored. Additionally, contact components are also suitable for drawing power from electrochemical cells with bipolar plates. Attached Figure Description

[0018] In the following description, exemplary embodiments of the invention are illustrated in more detail with reference to the accompanying drawings. In the drawings:

[0019] Figure 1 The contact assembly of the bipolar plate is shown in a top view.

[0020] Figure 2 It shows Figure 1 The side view of the component shown.

[0021] Figure 3 It shows Figure 1 A three-dimensional view of the components shown. Detailed Implementation

[0022] A contact assembly, generally indicated by reference numeral 1 in the accompanying drawings, is provided for use in the bipolar plate 10 of the fuel cell, which is shown only in its basic form. For details regarding the primary function of the bipolar plate in the fuel cell, refer to the prior art cited at the beginning.

[0023] The bipolar plate 10 is composed of two parallel half-sheets 2 and 3, each half-sheet 2 or 3 having an embossing element 4 or 5. The embossing elements 4 or 5 have a basic flattened dome shape. In the case of half-sheet 2, the embossing element 4 is formed as a protrusion. Conversely, the embossing element 5, visible in the figures, of half-sheet 3 is a recess. Apart from the embossing element 5, other structures of half-sheet 3 are not shown in the figures. The embossing elements 4 or 5 of the various half-sheets 2 and 3 face each other and may be components of further extended protruding areas that also have fluid-feature functions.

[0024] In the top view of contact assembly 1, four embossed elements 4, formed by half-sheets 2, define a rectangle with width d1 and height d2. Dimensions d1 and d2 refer to the center of the protrusion 4, denoted by M. A recess 5 is arranged within the rectangle defined by the center M of the protrusion 4, which is also denoted by M. All five embossed elements 4 and 5 contact a connecting pin 6, which is also commonly referred to as a contact element and is designed in this case as a spring tongue. The connecting pin 6, which protrudes laterally beyond half-sheets 2 and 3, has a maximum width BA and tapers towards a tip segment denoted by 8. The tip segment 8 is thicker than the rest of the entire plate-shaped connecting pin 6. The minimum thickness of the connecting pin 6 is denoted by dA.

[0025] During the assembly of contact assembly 1, connecting pin 6 is first placed on half sheet 2 such that connecting pin 6 laterally contacts four protrusions 4 in each case. The protrusions 4 may belong to the embossing structure 9 of half sheet 2, which may include other embossing elements. All embossing elements 4 protrude from the flat base surface of half sheet 2. The thickness of half sheet 2, expressed in dB, will be measured outside the embossing elements 4, i.e., in the flat area of ​​half sheet 2.

[0026] The connecting pin 6 is spaced apart from the flat areas of the half-sheets 2 and 3, even when the contact assembly 1 is fully assembled. The two lateral edges of the connecting pin 6 contact only the side surface 7 of the protrusion 4. In the example shown, the side surface 7 of the embossed element 4, i.e., the inclined area, is inclined at an angle α of 45° ± 15° relative to the plane where the half-sheet 2 is located. The height of each embossed element 4, 5 is denoted by H and is at least twice and at most eight times the sheet thickness dB. This applies to the bottom half-sheet 2 and the top half-sheet 3 in the arrangement shown. The arrangement of the half-sheets 2 and 3 shown in the figures does not imply any statement regarding the actual orientation of the bipolar plate 10 in space. In particular, the bipolar plate 10 may be vertically oriented in the fuel cell stack.

[0027] In an exemplary embodiment, the embossing elements 4 and 5 have a uniform diameter DP, which is at least 1.5 times and at most 2.5 times the width BA of the connecting pin 6. In contrast to the protrusion 4, the embossing element 5, formed as a recess in the half-sheet 3, contacts the connecting pin 6 centrally between the two lateral edges of the connecting pin. Therefore, unlike the embossing element 4, the embossing element 5 applies a vertical force to the connecting pin 6. In general, this provides five-point support for the connecting pin 6.

[0028] This support may cause slight bending of the connecting pin 6, which has at least a slight elastic property, but no contact is established between the connecting pin 6 and the flat areas of the half-sheets 2 and 3. In any case, a spring action is provided by the elastic deformation of the embossing elements 4, which serve as abutments for the connecting pin.

[0029] In an exemplary embodiment, the minimum thickness of the connecting pin 6, expressed in dB—the connecting pin being uniform except for the tip segment 8—is at least twice but no more than four times the sheet thickness dB. The elastic properties of the embossing elements 4 and 5 contribute even more to the stable holding of the connecting pin 6 between the halves of the sheets 2 and 3 than the elasticity of the connecting pin 6. The connecting pin 6 is used for metering purposes. Furthermore, by means of the connecting pin 6 and other elements not shown, electricity can be drawn from the fuel cell to which the bipolar plate 10 can be attributed.

[0030] List of reference numerals

[0031] 1 Contact component

[0032] 2 half-sheet

[0033] 3 half-sheet

[0034] 4 Imprinted elements, raised parts

[0035] 5 Imprinted elements and recesses

[0036] 6 Connecting pins and contact elements

[0037] 7. Side of the embossed element

[0038] 8. The tip section of the connecting pin

[0039] 9 Imprinted Structure

[0040] 10 bipolar plates

[0041] α Lateral angle

[0042] Maximum width of BA connecting pin

[0043] d1 Distance between the centers of the two protrusions

[0044] d2 is the distance between the centers of the two protrusions.

[0045] Minimum thickness of dA connecting pin

[0046] dB sheet thickness

[0047] Diameter of DP embossed element

[0048] The height of the H embossed element

Claims

1. A contact assembly for a bipolar plate, the contact assembly comprising two half-sheets spaced parallel to each other and belonging to a bipolar plate (10), wherein, Each half-sheet has an embossing element, and the embossing elements of the two half-sheets face each other, wherein a connecting pin (6) inserted between the half-sheets contacts the embossing element of the half-sheet, the connecting pin (6) contacts four embossing elements of the first half-sheet (2) and a single embossing element of the second half-sheet (3), the four embossing elements of the first half-sheet being arranged in a rectangular pattern and formed as protrusions (4), and the single embossing element of the second half-sheet being formed as a recess (5), wherein the recess (5) of the second half-sheet (3) is arranged within a rectangle defined by the four protrusions (4) of the first half-sheet (2).

2. The contact assembly according to claim 1, characterized in that, In a top view of the bipolar plate (10), the embossing element of the first half sheet (2) is offset relative to at least one embossing element of the second half sheet (3).

3. The contact assembly according to claim 1, characterized in that, In each case, the connecting pin (6) is tangent to the protrusion (4) arranged in a rectangular pattern in the lateral region and centrally contacts the recess (5) of the second half sheet (3), the lateral region being positioned at an angle of at least 5° and at most 60° relative to the plane on which the half sheet is arranged.

4. The contact assembly according to any one of claims 1 to 3, characterized in that, The connecting pin (6) contacts only the embossing element of the half sheet, and does not contact the flat area outside the embossing element of the half sheet.

5. The contact assembly according to any one of claims 1 to 3, characterized in that, The connecting pin (6) is designed as a spring tongue.

6. The contact assembly according to any one of claims 1 to 3, characterized in that, The embossing element of at least one half of the half sheet is designed as an elastic abutment of the connecting pin (6).

7. Use of a contact assembly according to any one of claims 1 to 6 for performing voltage measurements on a bipolar plate (10) and for drawing power from an electrochemical cell having said bipolar plate (10).

8. A method for contacting a bipolar plate (10) composed of two half-sheets, wherein, Contact elements are inserted between the half-sheets such that the contact elements elastically contact a plurality of approximately dome-shaped embossing elements of the half-sheets, and the contact elements contact four embossing elements of the first half-sheet (2) and a single embossing element of the second half-sheet (3). The four embossed elements of the first half sheet are arranged in a rectangular pattern and formed as protrusions (4), and the single embossed element of the second half sheet is formed as a recess (5), wherein the recess (5) of the second half sheet (3) is arranged within a rectangle defined by the four protrusions (4) of the first half sheet (2).

9. The method according to claim 8, characterized in that, The contact element is initially placed on the first half sheet (2) and is thereby laterally guided by a plurality of imprinting elements of the first half sheet (2), and in another step the contact element is loaded by a single imprinting element of the second half sheet (3).

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