Bipolar plate, connection system and fuel cell system
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- ROBERT BOSCH GMBH
- Filing Date
- 2024-07-15
- Publication Date
- 2026-05-20
AI Technical Summary
In fuel cell stacks, existing plug-in connections for cell voltage monitoring systems are prone to dislodgment due to vibrations and relative movements, compromising the reliability of electrical connections and requiring secure, long-lasting contact solutions.
A bipolar plate with a plug receptacle design featuring an insertion section and a holding section, where the holding section is wider than the insertion section, generating a clamping force to secure the plug contact, and an elevation to enhance resistance against dislodgment, ensuring stable electrical connections.
The design effectively prevents plug contact migration during vibrations and relative movements, ensuring reliable and secure electrical connections within the fuel cell system, enhancing both safety and operational efficiency.
Smart Images
Figure EP2024070007_23012025_PF_FP_ABST
Abstract
Description
[0001] Description
[0002] title
[0003] Bipolar plate, connection system and fuel cell system
[0004] Description
[0005] The invention relates to a bipolar plate having the features of independent patent claim 1, a connection system having the features of independent patent claim 8 and a fuel cell system having the features of independent patent claim 11.
[0006] It is already known from the state of the art that fuel cell stacks consist of many individual fuel cells connected in series to form a larger array. To monitor, control, or regulate these systems, it is advantageous to know not only the operating parameters of the entire cell stack, but also the operating parameters of each individual cell within that stack. So-called CVM systems (Cell Voltage Monitor Systems) are used to measure the voltage or other operating parameters of individual fuel cells within a fuel cell stack.
[0007] Plug connections are often used to connect the cells to the CVM system, with metallic pins being inserted into the cell stack.
[0008] The contact establishes an electrically conductive connection between the evaluation electronics of the cell monitoring system and the bipolar plates of a fuel cell stack, enabling cell voltages to be measured. Due to sealing requirements and accessibility in motor vehicles, the connectors must remain in the cell stack for the entire service life of the stack. Therefore, it is important to ensure that the contacts are reliably prevented from migrating out of their sockets due to vibrations or other relative movements.
[0009] The above object is achieved by a bipolar plate having the features of independent patent claim 1, by a connection system having the features of independent patent claim 8, and by a fuel cell system having the features of independent patent claim 11. Further features and details of the invention emerge from the subclaims, the description, and the drawings. Features and details described in connection with the bipolar plate according to the invention naturally also apply in connection with the connection system according to the invention and / or in connection with the fuel cell system according to the invention, and vice versa, so that with regard to the disclosure of the individual aspects of the invention, reference is or can always be made reciprocally.
[0010] A first aspect of the invention is a bipolar plate for a fuel cell stack of a fuel cell system, comprising a first separator plate and a second separator plate, with at least one distribution region for distributing the reaction gases into an active region. The at least one distribution region has at least one plug receptacle for a plug contact of a cell voltage monitoring unit.
[0011] The at least one plug receptacle has an insertion section for inserting a plug contact, in particular a plug loop, and a holding section for holding the plug contact, wherein the holding section is arranged downstream of the insertion section in an insertion direction of the plug contact, and wherein a maximum insertion width of the insertion section corresponds to a maximum of 100%, preferably a maximum of 99%, preferably a maximum of 90%, more preferably a maximum of 70%, of a maximum holding width of the holding section. In special embodiments, it is also conceivable for the holding section to be smaller than the insertion section. The holding section of the plug receptacle is designed such that a plugged-in plug contact is in contact with a transition region of the holding section. Particularly advantageously, the plug contact and the holding section are designed such that a clamping force is exerted on a plug contact in the plugged-in state.
[0012] In this case, the maximum holding width of the holding section refers to the maximum extension of the holding section along the width of the bipolar plate. Accordingly, the maximum insertion width of the insertion section corresponds to the maximum extension of the insertion section along the width of the bipolar plate. To ensure secure retention of the plug contact or plug loop in the plug receptacle, the maximum holding width of the holding section is greater than the maximum insertion width of the insertion section.
[0013] There is a transition section between the holding section and the insertion section. It is particularly advantageous if the holding section widens in this transition area.
[0014] This is particularly advantageous for plug loops, since they widen after being inserted through the insertion section into the holding section, so that the clamping force on the plug loop is generated at a transition between the holding section and the insertion section of the plug receptacle due to the resulting constriction.
[0015] In order to release or detach the connector loop, the clamping force must be overcome. This is because the connector loop must first be compressed before it can be removed from the connector receptacle. This has a positive effect on the behavior of the electrical connection between the connector loop and the bipolar plate, as it prevents or impedes the plug contact from moving out in the event of vibration or other relative movement of the fuel cell system, or during operation of the vehicle with the fuel cell system. The clamping force that occurs at the transition between the insertion section and the holding section must be overcome in order to remove the plug contact from the connector receptacle and thus release the electrical connection.
[0016] The connector receptacle is particularly easy to manufacture because the separator plates are embossed for bipolar plates. The connector receptacles can be embossed as a recess into the separator plates during the general embossing process.
[0017] This connector receptacle with the insertion section and the holding section not only has a positive effect on the safety of the electrical connection to be created or to be created, but also on the costs and the general function of the fuel cell.
[0018] To insert the plug loop into the insertion section of the plug receptacle, the latter is designed in such a way that there is an opening so that the plug loop can be inserted.
[0019] Within the scope of the invention, it may be advantageous for the holding section of the plug receptacle to have a circular or oval or square or polygonal base area.
[0020] It is conceivable that the base area of the holding section, in combination with the base area of the insertion section, has a spoon-like basic shape. This makes it particularly easy to create the criterion that the maximum holding width of the holding section is greater than the maximum insertion width of the insertion section.
[0021] By means of these shapes of the base area of the holding section, it is particularly easy to design the maximum holding width of the holding section in relation to the maximum width of the insertion section so that it is larger and at the same time is easy to manufacture by the stamping process without having to introduce additional forces into the bipolar plate.
[0022] Within the scope of the invention, it is conceivable that the holding section of the plug receptacle has at least one widening, wherein the widening has an expansion angle of 1° to 80°, preferably 10° to 60°, preferably 15° to 45°, to the insertion section.
[0023] The expansion angle can be viewed from the central axis or the longitudinal axis of the connector receptacle. The longitudinal axis can then extend along the length of the bipolar plate, with the length corresponding to the maximum extension of the bipolar plate.
[0024] It is therefore advantageous if the holding section or the connector receptacle generally has a mirror symmetry around the longitudinal axis of the connector receptacle. This ensures that the plug contact or the connector loop is or can be held on both sides using the same clamping force.
[0025] Within the scope of the invention, it can be provided that the insertion section of the plug receptacle has a rectangular or trapezoidal base area.
[0026] Particular care must be taken to ensure that the maximum insertion width of the insertion section is smaller than the maximum holding width of the holding section. A trapezoidal base has proven particularly advantageous. The parallel sides of the trapezoid are arranged so that one side of the opening is used to insert the plug loop into the insertion section and the other side is positioned in the transition area between the holding section and the insertion section. It is particularly advantageous if the smaller of the two parallel sides of the trapezoid corresponds to the transition area. This enables particularly easy insertion of the plug or plug loop into the insertion section via a wider opening and at the same time generates a sufficiently large holding force or clamping force at the transition to the holding section.
[0027] It is also conceivable for the first separator plate or the second separator plate to have a raised portion in the base area of the holding portion of the connector receptacle. This raised portion can be easily created during the stamping process, since the raised portion only needs to be provided in the stamping shape of the bipolar plate.
[0028] The elevation in the base of the holding section serves as additional security against the plug or the plug loop wandering out or becoming loose from the plug receptacle due to vibration and relative movements.
[0029] When inserting the plug or plug loop through the insertion section into the holding section, the plug contact or plug loop is pushed over the raised portion, so that in the event of vibration or other relative movement, not only the clamping force but also the insertion resistance over the raised portion must be overcome to prevent the plug from becoming loose or dislodged. This thus simply increases the security against the plug or plug loop becoming loose or dislodged from the plug receptacle during operation of the fuel cell system.
[0030] It is also conceivable for the elevation in the base area of the holding section of the plug receptacle to be symmetrical or asymmetrical. In this case, symmetrical means an elevation shaped like a spherical cap. Whereas asymmetrical means that the elevation has a circular or oval basic shape, and the gradient of the elevation is asymmetrical with respect to the insertion direction and the withdrawal direction opposite the insertion direction. It is advantageous if the gradient of the elevation in the insertion direction of the plug contact or the plug loop is less than the gradient in the withdrawal direction of the plug contact. As a result, the resistance or force required to insert the plug contact is less than the resistance or force required to move out or release the plug contact.
[0031] By varying the slope of the raised portion in the base of the holding section, the force can be adjusted depending on the direction of movement. It is also conceivable to create an undercut, allowing the raised portion to be shaped like a hook.
[0032] Within the scope of the invention, it is optionally possible for a height of the elevation in the base area of the holding section to correspond to 5% to 100%, preferably 10% to 80%, more preferably 15% to 50% of a separator plate height of the first separator plate or the separator plate height of the second separator plate.
[0033] By adjusting the height of the bump, the resistance can be easily adjusted both when inserting and releasing the connection.
[0034] A second aspect of the invention is a connection system for a fuel cell system with at least one plug contact of a cell voltage monitoring unit and with at least one bipolar plate according to the first aspect of the invention. The plug contact is a plug loop that is inserted into the plug receptacle of the bipolar plate. A maximum loop width of the plug loop in the holding section corresponds to at least 105%, preferably at least 110%, more preferably at least 115% of the maximum insertion width of the insertion section of the plug receptacle.
[0035] This is particularly advantageous because the connector loop expands in the holding section, or can expand due to the geometric design of the connector receptacle. This expansion of the connector loop, or the fact that the maximum loop width is greater than the maximum insertion width of the insertion section, simplifies and ensures the secure mounting and connection of the cell voltage monitoring unit in the bipolar plate.
[0036] Furthermore, within the scope of the invention, it can be provided that the connector loop is partially in contact with the holding section in a transition area. The holding area, and respectively the connector loop, is designed to exert a clamping force on the connector loop in the transition area. This ensures in a simple manner that the electrical connection is and can be established and that the connector loop does not detach from the connector receptacle due to vibration and relative movement, or can only be detached by overcoming the clamping force.
[0037] With regard to the invention, it is conceivable that the plug loop is pushed over the elevation of the first separator plate or the second separator plate in a holding position.
[0038] When inserting the connector loop into the connector receptacle, the resistance created by the narrower insertion section must first be overcome. To further improve or optimize the retention, the connector loop must be pushed over the raised portion. This additional resistance when inserting the connector loop, in turn, leads to increased resistance to loosening or migration due to vibrations and other relative movements. Holding the connector loop behind the raised portion thus provides greater security against the connector loop becoming detached from the connector receptacle due to vibrations and other relative movements.
[0039] A third aspect of the invention is a fuel cell system comprising a fuel cell stack having a plurality of bipolar plates according to the first aspect of the invention and the cell voltage monitoring unit having a plurality of plug contacts, wherein the bipolar plates and the plug contacts are connected via a connection system according to the second aspect of the invention.
[0040] Advantages described in detail for the bipolar plates according to the first aspect of the invention also apply to the connection system according to the second aspect of the invention and to the fuel cell system according to the third aspect of the invention.
[0041] Further advantages, features, and details of the invention will become apparent from the following description, which describes several embodiments of the invention in detail with reference to the drawings. The features mentioned in the claims and in the description may be essential to the invention individually or in any combination. The invention is illustrated in the following figures:
[0042] Figure 1 is a schematic representation of a bipolar plate with a plug receptacle or a plurality of plug receptacles in a plan view,
[0043] Figure 2 is a schematic representation of a section of a connector receptacle of a bipolar plate in a plan view,
[0044] Figure 3 is a schematic representation of a section of a connector receptacle of a bipolar plate in a sectional view,
[0045] Figure 4 is a schematic representation of a connection system for a fuel cell system in a plan view,
[0046] Figure 5 is a schematic representation of a fuel cell system in a sectional view.
[0047] Figures 1 to 3 depict a bipolar plate. Figures 2 and 3 depict the section shown in Figure 1.
[0048] The bipolar plate 10 for a fuel cell stack 12 of a fuel cell system 14 according to Figure 1 has a first separator plate 16 and a second separator plate 18. The bipolar plate 10 is formed by assembling the first separator plate 16 and the second separator plate 18. The bipolar plate 10 has at least one distributor region 20 for distributing the reaction gases in an active region 22. When the bipolar plate is in use, the reaction of the supplied gases, in particular air and hydrogen, takes place at the proton exchange membrane in the active region 22. The at least one distributor region 20 has at least one plug receptacle 24 for a plug contact 26 and a cell voltage monitoring unit 30. The at least one plug receptacle 24 is divided into an insertion section 32 for inserting a plug contact 26, in particular a plug loop 28, and a holding section 34 for holding the plug contact 26.The holding section 34 is arranged downstream of the insertion section 32 in an insertion direction 36, the plug contact 26. The maximum insertion width BE of the insertion section 32 corresponds to a maximum holding width BH of the holding section 34 at a maximum of 100%, preferably a maximum of 990%, preferably a maximum of 90%, more preferably a maximum of 70%.
[0049] In the present embodiment, the maximum insertion width BE of the insertion section 32 corresponds to a maximum of 90% of the maximum holding width BH of the holding section.
[0050] The holding section 34 of the plug receptacle 24 has an oval base 38. The base 38 can also be circular, square, or polygonal.
[0051] As can be seen particularly in Figure 2, the holding section 34 of the plug receptacle 24 has at least one widening 40. The widening 40 has an expansion angle α. In the present exemplary embodiment, this expansion angle lies in a range between 1° and 80° and is relative to the insertion section 32. It can be seen in Figure 2 that the widening directly adjoins the insertion section. Accordingly, the holding section 34 immediately widens to its maximum holding width BH, starting from the end of the insertion section 32.
[0052] The insertion section 32 of the plug receptacle 24 has a rectangular base 38. A trapezoidal base 38 would also be conceivable at this point.
[0053] As can be seen in Figure 3, the first separator plate 16 has a raised portion 44 in the base surface 38 of the holding portion 34 of the plug receptacle 24. In an embodiment not shown here, it is also possible for the second separator plate 18, instead of the first separator plate 16, to have the raised portion 44 in its base surface 38 of the holding portion 34 of the plug receptacle 24. In this case, the raised portion 44 of the base surface 38 of the holding portion 34 of the present embodiment is designed symmetrically. This means that the same force must be exerted both when inserting a plug in the insertion direction and when withdrawing the plug contact 26 in the opposite direction to the insertion direction.
[0054] The elevation 44 has an elevation height HE. The elevation height HE lies between 5% and 100% of a separator plate height H_SP1 of the first separator plate 16. If the elevation 44 is provided in the second separator plate 18, the elevation height HE corresponds to 5% to 100% of the separator plate height H_SP2.
[0055] Figure 4 shows a connection system 46 for a fuel cell system 14 with at least one plug contact 26 of a cell voltage monitoring unit 30 and with at least one bipolar plate 10 according to one of Figures 1 to 3. The plug contact 26 is designed as a plug loop 28 and is inserted into the plug receptacle 24 of the bipolar plates 10.
[0056] As can be seen in Figure 4, the maximum loop width BS of the plug loop 28 in the holding section 34 is greater than the maximum insertion width BE of the insertion section 32 of the plug receptacle 24. In the illustrated embodiment, the maximum loop width BS of the plug loop 28 corresponds to at least 105% of the maximum insertion width BE of the insertion section 32.
[0057] The plug loop 28 is designed such that it is in contact with the holding section 34 in sections in a transition region 48. This transition region 48 can also be regarded as a transition region between the insertion section 32 and the holding section 34. This transition region 48 is particularly advantageous if the holding section 34 has the widening angle α in this region. As a result, the plug loop, after being pushed through the insertion section 32 into the holding section 34, can widen to assume its maximum loop width BS. To assume a particularly secure position, the plug loop 28 is pushed over the elevation 44 of the first separator plate 16.As a result, the plug loop 28 is held in its holding position HP both by the clamping force FK in the transition region 48 and by the elevation 44, so that migration out due to vibrations or other relative movements during operation of the fuel cell or the fuel cell stack is prevented.
[0058] Figure 5 shows a fuel cell system 14 with a fuel cell stack 12 having a plurality of bipolar plates 10. In addition, the fuel cell system 14 includes a cell voltage monitoring unit 30 with a plurality of plug contacts 26. The bipolar plates 10 and the plug contacts 26 of the voltage monitoring unit 30 are connected to one another via the connection system 46, as shown in Figure 4.
[0059] This ensures that the electrical connection between the plug contacts 26 and the plurality of bipolar plates 10 of the fuel cell stack 2 remains intact even during operation, so that monitoring of the fuel cell stack 12 is guaranteed.
Claims
Claims 1. Bipolar plate (10) for a fuel cell stack (12) of a fuel cell system (14), with a first separator plate (16) and a second separator plate (18), with at least one distributor region (20) for distributing the reaction gases into an active region (22), wherein the at least one distributor region (20) has at least one plug receptacle (24) for a plug contact (26) of a cell voltage monitoring unit (30), characterized in that the at least one plug receptacle (24) has an insertion section (32) for inserting a plug contact (26), in particular a plug loop (28), and a holding section (34) for holding the plug contact (26), wherein the holding section (34) is arranged downstream of the insertion section (32) in an insertion direction (36) of the plug contact (26), and wherein a maximum insertion width (BE) of the insertion section (32) is a maximum of 100%, preferably a maximum 99%, preferably a maximum of 90%, more preferably a maximum of 70%,a maximum holding width (BH) of the holding section (34).
2. Bipolar plate (10) according to claim 1, characterized in that the holding section (34) of the plug receptacle (24) has a circular or oval or square or polygonal base area (38).
3. Bipolar plate (10) according to claim 1 or 2, characterized in that the holding section (34) of the plug receptacle (24) has at least one widening (40), wherein the widening (40) has an widening angle (α) of 1° to 80°, preferably 10° to 60°, more preferably 15° to 45°, to the insertion section (32).
4. Bipolar plate (10) according to one of the preceding claims, characterized in that the insertion section (32) of the plug receptacle (24) has a rectangular or trapezoidal base area (42).
5. Bipolar plate (10) according to one of the preceding claims, characterized in that the first separator plate (16) or the second separator plate (18) has an elevation (44) in the base surface (38) of the holding section (34) of the plug receptacle (24).
6. Bipolar plate (10) according to claim 5, characterized in that the elevation (44) in the base surface (38) of the holding section (34) of the plug receptacle (24) is symmetrical or asymmetrical.
7. Bipolar plate (10) according to one of claims 5 or 6, characterized in that an elevation height (HE) of the elevation (44) in the base area (38) of the holding section (34) corresponds to 5% to 100%, preferably 10% to 80%, more preferably 15% to 50%, of a separator plate height (H_SP1) of the first separator plate (16) or the separator plate height (H_SP2) of the second separator plate (18).
8. Connection system (46) for a fuel cell system (14) with at least one plug contact (26) of a cell voltage monitoring unit (30) and with at least one bipolar plate (10) according to one of the preceding claims, wherein the plug contact (26) is a plug loop (28) which is pushed into the plug receptacle (24) of the bipolar plate (10), wherein a maximum loop width (BS) of the plug loop (28) in the holding section (34) corresponds to at least 105%, preferably at least 110%, more preferably at least 115%, of the maximum insertion width (BE) of the insertion section (32) of the plug receptacle (24).
9. Connection system (46) according to claim 8, characterized in that the plug loop (28) is in partial contact with the holding section (34) in a transition region (48).
10. Connection system (46) according to claim 8 or 9, characterized in that the plug loop (28) is pushed over the elevation (44) of the first separator plate (16) or the second separator plate (18) in a holding position (HP).
11. Fuel cell system (14) with a fuel cell stack (12) with a A plurality of bipolar plates (10) according to one of claims 1 to 7 and the cell voltage monitoring unit (30) having a plurality of plug contacts (26), wherein the bipolar plates (10) and the plug contacts (26) are connected via a connection system (46) according to one of claims 8 to 10.