CN115763923A - End plate of fuel cell and cell stack - Google Patents

Abstract

The present invention proposes an end plate for a fuel cell, the end plate being intended to be arranged at one end of a stack of fuel cells, the end plate comprising: an end plate body (1) formed with an external inlet (11), an external outlet (12) and first (13) and second (14) openings for connection to the cells of the stack; and a rack and pinion mechanism (2) having a first operating state and a second operating state, wherein the rack and pinion mechanism (2) is configured such that in the first operating state the outer inlet (11) is connected to the first opening (13) and the outer outlet (12) is connected to the second opening (14); in a second operating state, the outer inlet (11) is connected to the second opening (14) and the outer outlet (12) is connected to the first opening (13). A stack of fuel cells is also presented. By means of the invention, the direction of flow of the fluid within the cell stack can be changed by means of the gear rack mechanism of the end plate.

Description

End plate of fuel cell and cell stack

Technical Field

The present invention relates to the field of fuel cells, in particular hydrogen fuel cells, and in particular to an end plate for a fuel cell and a stack for a fuel cell.

Background

The new energy automobile and energy conservation and emission reduction become urgent matters of the automobile industry in the face of severe challenges of global warming, air pollution and energy depletion, and the traditional internal combustion engine automobile is promoted to be transformed to a new energy electric automobile which is more green and environment-friendly. In electric vehicles, fuel cells, particularly proton exchange membrane cells (PEMFCs), have received much attention as a promising efficient and environmentally friendly power source. The proton exchange membrane fuel cell generally uses hydrogen as fuel, oxygen or air as oxidant, and converts chemical energy into electric energy in an electrochemical mode, and the emission is water, so that zero emission in the true sense is realized. Moreover, the proton exchange membrane fuel cell has the advantages of high energy conversion rate, low-temperature starting, no electrolyte leakage and the like due to the adoption of the solid polymer membrane as the electrolyte.

A stack of a proton exchange membrane fuel cell generally includes end plates arranged at both ends and a plurality of cell units stacked between the end plates. The end plates are important components of the pem fuel cell and function primarily to hold the cells in place, to allow fluid to flow into and out of the cells. For example, the end plate may be used to introduce fuel gas, oxidant, and coolant, and to discharge anode off-gas, cathode off-gas, and coolant.

Taking the end plate arranged on the cathode side as an example, an oxidant, such as fresh air, is introduced into the cathode side of the cell unit through an external inlet of the end plate and electrochemical reaction occurs, and the resulting cathode off-gas is discharged through an external outlet of the end plate. Along the air flow path within the stack, the closer to the external outlet, the lower the oxygen content and the higher the water content. In the case where the end plates are used to introduce and discharge the coolant, the temperature is higher the closer to the external outlet along the flow path of the coolant within the stack.

During fuel cell operation, fuel gas, oxidant or coolant is unevenly distributed within the stack. This imbalance can also lead to inconsistent aging of various portions of the stack after extended operation of the fuel cell.

Disclosure of Invention

It is an object of the present invention to provide an improved end plate for a fuel cell and a cell stack for changing the direction of fluid flow within the cell stack through the end plate.

According to a first aspect of the present invention, there is provided an end plate of a fuel cell, the end plate being for arrangement at one end of a stack of fuel cells, the end plate comprising: an end plate body formed with an external inlet port for introducing a first fluid into the cell stack, an external outlet port for discharging a second fluid from the cell stack, and first and second openings for connection to the battery cells of the cell stack; and a rack and pinion mechanism having a first operating state and a second operating state, wherein the rack and pinion mechanism is configured to enable the external inlet to communicate to the first opening and the external outlet to communicate to the second opening in the first operating state; in a second operating state, the outer inlet is connected to the second opening and the outer outlet is connected to the first opening.

According to a second aspect of the present invention, a stack of fuel cells is provided, wherein the stack comprises two end plates and at least one cell unit arranged between the end plates, at least one of the end plates being an end plate according to the present invention.

The invention has the positive effects that: the direction of flow of the fluid within the end plate can be changed by changing the communication state of the external inlet and the external outlet with the first opening and the second opening by the rack and pinion mechanism of the end plate, so that the first fluid flowing in from the external inlet can selectively flow into the battery cells of the battery stack via one of the first opening and the second opening, and correspondingly the second fluid from the battery cells flows from the other of the first opening and the second opening to the external outlet and is discharged. In turn, the direction of fluid flow within the cells of the stack is changed. This breaks the original uneven distribution of fluid within the stack. In addition, inconsistent aging of various parts of the stack due to fixed fluid flow directions can be avoided.

Drawings

The principles, features and advantages of the present invention may be better understood by describing the invention in more detail below with reference to the accompanying drawings. The drawings comprise:

fig. 1 schematically shows, in a cross-sectional view, an end plate of a fuel cell according to an exemplary embodiment of the invention, wherein a rack and pinion mechanism is in a first operating state;

fig. 2 schematically shows, in a cross-sectional view, an end plate of a fuel cell according to an exemplary embodiment of the invention, with a rack and pinion mechanism in a second operating state;

fig. 3 schematically shows an end plate of a fuel cell according to an exemplary embodiment of the invention in a perspective view

Fig. 4A schematically illustrates, in cross-section, an end plate according to an exemplary embodiment of the invention, with a rack and pinion mechanism in a first operational state;

FIG. 4B shows the end plate shown in FIG. 4A in perspective view, with the second plate not shown for clarity;

FIG. 4C schematically illustrates a partial enlarged view of FIG. 4A;

FIG. 5A schematically illustrates, in cross-section, an end plate according to an exemplary embodiment of the present invention, with the rack and pinion mechanism in a second operational state; and

fig. 5B shows the end plate shown in fig. 5A in a perspective view, wherein the second plate is not shown for clarity.

Detailed Description

In order to make the technical problems, technical solutions and advantageous effects of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings and exemplary embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the scope of the invention.

It is to be understood that in this document the expressions "first", "second" etc. are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or as implying a number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. As used herein, "plurality" means at least two, e.g., two, three, etc., unless explicitly specified otherwise.

The principle of the present invention will be described in detail below by taking PEMFCs as an example. However, it will be appreciated by those skilled in the art that the present invention is not only applicable to PEMFCs, but is also applicable to other types of fuel cells in which fluids are introduced and discharged through end plates, particularly fuel cells for powering vehicles.

Fig. 1 schematically shows an end plate of a fuel cell according to an exemplary embodiment of the present invention in a cross-sectional view.

The PEMFC has a cell stack including end plates disposed at both ends of the cell stack and a plurality of unit cells stacked on each other between the end plates. For example, a cell stack for a PEMFC for a vehicle may have hundreds or even more of cells stacked on each other. The cell unit generally includes bipolar plates, an anode diffusion layer, a Membrane Electrode Assembly (MEA), and a cathode diffusion layer, which are sequentially stacked. The membrane electrode assembly comprises an anode catalyst layer, a proton exchange membrane and a cathode catalyst layer. At the bipolar plates, anode and cathode fluids are introduced into the respective anode and cathode flow channels, and the current produced by the cell is collected.

Typically, the anode fluid is a fuel gas (hydrogen in this embodiment) and the cathode fluid is an oxidant (oxygen-containing air in this embodiment). Of course, other suitable anode and cathode fluids may be used. The introduced anode fluid and cathode fluid are diffused at the anode diffusion layer and the cathode diffusion layer, respectively, and transferred to the anode catalyst layer and the cathode catalyst layer, respectively. Further, the fuel gas undergoes an electrochemical reaction at the anode catalyst layer, which may be represented by the following chemical reaction equation in the present embodiment:

the generated protons reach the cathode catalyst layer through the proton exchange membrane and electrochemically react with the oxidant at the cathode catalyst layer, which can be expressed by the following chemical reaction equation in this embodiment:

thereby, the chemical energy of the reaction gas is converted into electric energy.

Anode and cathode fluids may be introduced into the stack through end plates, and anode and cathode exhaust gases may also be exhausted through the end plates.

The electrochemical reaction is accompanied by a release of heat, and the temperature of the stack will rise accordingly. In order to maintain the stack at an appropriate operating temperature, internal coolant channels for flowing a coolant therethrough may be formed in the stack so as to cool the stack with the coolant flowing through the internal coolant channels during operation of the stack. Coolant may be introduced into the stack through the end plates and coolant flowing through the internal coolant channels may also be exhausted through the end plates.

As shown in fig. 1, the end plate includes an end plate body 1, the end plate body 1 being formed with: an outer inlet 11 and an outer outlet 12; and a first opening 13 and a second opening 14 for connection to the battery cells of the stack. The end plate further comprises a rack and pinion mechanism 2 having a first operating state and a second operating state. The rack and pinion mechanism 2 is configured such that the outer inlet 11 communicates to the first opening 13 and the outer outlet 12 communicates to the second opening 14 in the first operating state; in the second operating state, the outer inlet 11 is made to communicate with the second opening 14 and the outer outlet 12 is made to communicate with the first opening 13.

By changing the communication state of the external inlet 11 and the external outlet 12 with the first opening 13 and the second opening 14, the flow direction of the fluid within the end plate can be changed, so that the first fluid flowing in from the external inlet 11 can selectively flow into the battery cells of the stack via one of the first opening 13 and the second opening 14, and correspondingly the second fluid from the battery cells flows from the other of the first opening 13 and the second opening 14 to the external outlet 12 and is discharged. In turn, the direction of fluid flow within the cells of the stack is changed. Thereby, an uneven distribution of fluid within the stack may be broken. In addition, inconsistent aging of various parts of the stack due to fixed fluid flow directions can be avoided.

The external inlet 11 may be used to direct a first fluid so that the first fluid can participate in reactions or heat exchange within the stack. The first fluid may be fuel gas, an oxidant or a coolant. The external outlet 12 may be used to direct the second fluid out of the stack. The second fluid may be anode exhaust gas, cathode exhaust gas, or a coolant in superheat exchange with the stack.

Exemplarily, the end plate may comprise a motor for driving the gear rack mechanism 2, which motor may be arranged on the outside of the end plate body 1 or within the end plate body 1. Thus, the rack mechanism 2 can be driven by the motor as needed to change the communication state of the external inlet 11 and the external outlet 12 with the first opening 13 and the second opening 14 during the operation of the fuel cell or at the time of maintenance or repair of the fuel cell. Alternatively or additionally, the end plate may comprise a manual drive unit for driving the rack and pinion mechanism 2, which may be arranged at least partially outside the end plate body 1, such that a user can operate the rack and pinion mechanism 2 by the manual drive unit to change the communication state of the external inlet 11 and the external outlet 12 with the first opening 13 and the second opening 14.

In the embodiment shown in fig. 1, the end plate body 1 is formed with at least four main passages including a first main passage MP1 connecting the external inlet 11 and the first opening 13, a second main passage MP2 connecting the external outlet 12 and the second opening 14, a third main passage MP3 connecting the external inlet 11 and the second opening 14, and a fourth main passage MP4 connecting the external outlet 12 and the first opening 13. In the first operation state, the rack and pinion mechanism 2 opens the first main passage MP1 and the second main passage MP2, and closes the third main passage MP3 and the fourth main passage MP 4; in the second operation state, the rack and pinion mechanism 2 closes the first and second main passages MP1 and MP2, and opens the third and fourth main passages MP3 and MP4. Fig. 1 shows only the rack and pinion mechanism 2 in the first operating state, in which the first and second main passages MP1 and MP2, which are open, are indicated by solid lines with arrows, and the third and fourth main passages MP3 and MP4, which are closed, are indicated by broken lines with arrows. Thus, when the rack and pinion mechanism 2 is in the first operating state, the first opening 13 serves as an internal inlet for supplying fluid to the battery cell, and the second opening 14 serves as an internal outlet for drawing fluid from the battery cell; conversely, when the rack and pinion mechanism 2 is in the second operational state, the first opening 13 serves as an internal outlet for drawing fluid from the battery cell, and the second opening 14 serves as an internal inlet for supplying fluid to the battery cell.

Fig. 2 schematically shows an end plate of a fuel cell according to an exemplary embodiment of the present invention in a cross-sectional view, in which the rack and pinion mechanism 2 is in a second operating state. In fig. 2, the opened third and fourth main channels MP3 and MP4 are indicated by solid lines with arrows, and the closed first and second main channels MP1 and MP2 are indicated by broken lines with arrows.

As shown in fig. 1 and 2, the end plate body 1 may have a loop-shaped annular passage, and the outer inlet 11, the first opening 13, the outer outlet 12, and the second opening 14 may be sequentially connected to the annular passage at different circumferential positions of the annular passage, thereby forming a first main passage MP1, a second main passage MP2, a third main passage MP3, and a fourth main passage MP4. The rack and pinion mechanism 2 may be arranged substantially centrally in the annular channel.

The rack and pinion mechanism 2 includes a pinion 21, a first rack 22, and a second rack 23. The first rack 22 and the second rack 23 can be driven by the gear 21 to reciprocate, thereby switching the rack and pinion mechanism 2 between the first operating state and the second operating state. In a first operating state of the rack and pinion mechanism 2, the first rack 22 is located at least partially in the fourth main channel MP4 and blocks the fourth main channel MP4, and the second rack 23 is located at least partially in the third main channel MP3 and blocks the third main channel MP3. In a second operating state of the rack and pinion mechanism 2, the first rack 22 is located at least partially in the first main passage MP1 and blocks the first main passage MP1, and the second rack 23 is located at least partially in the second main passage MP2 and blocks the second main passage MP2. Only the rotation gear 21 is needed to synchronously drive the first rack 22 and the second rack 23 to change the open and closed states of the respective main passages. Such a rack and pinion mechanism 2 can reliably cause the open and closed states of the first main passage MP1 and the second main passage MP2 to be changed in synchronization, and cause the open and closed states of the third main passage MP3 and the fourth main passage MP4 to be changed in synchronization, by a simple operation.

The first rack 22 and the second rack 23 may be respectively disposed at both sides of the gear 21 and moved in opposite directions by the gear 21. The first rack 22 and the second rack 23 may extend into the annular channel to block the respective main channels.

The first rack 22 and the second rack 23 may respectively include a rack body and a sealing strip for reinforcing a blocking effect to the corresponding main channel. The weather strip may be made of an elastic material and embedded in the rack body or adhered to the rack body. Alternatively, the weather strip is formed on the rack body by spraying the sealant to the rack body. It should be understood that the sealing strip is not necessary in view of the basic idea of the invention, since the main channel does not have to be interrupted in a completely gas-tight manner, but only if the interruption is able to achieve the desired sealing level.

As shown in fig. 1 and 2, the end plates may, for example, have a centrosymmetric configuration, which is advantageous for saving production and assembly costs.

Fig. 3 schematically shows an end plate of a fuel cell according to an exemplary embodiment of the present invention in a perspective view. As shown in fig. 3, the end plate body 1 may comprise a first plate 15 and a second plate 16 stacked on each other (only the outer contour of the second plate 16 is schematically shown in dashed lines), the rack and pinion mechanism 2 being arranged between the first plate 15 and the second plate 16. The first main passage MP1, the second main passage MP2, the third main passage MP3, and the fourth main passage MP4 may be at least partially formed collectively by grooves formed in the first plate 15 and the second plate 16, respectively. The part of the structure of the first plate 15 that should be obscured by the second plate 16 is shown schematically here to more clearly show the configuration of the end plates.

Fig. 4A schematically shows in a cross-sectional view an end plate according to an exemplary embodiment of the invention, wherein the rack and pinion mechanism 2 is in a first operating state. Fig. 4B shows the end plate shown in fig. 4A in a perspective view, wherein the second plate 16 is not shown for clarity.

In this embodiment, the first and third main passages MP1 and MP3 are configured to guide a fuel gas or an oxidant, for example, so that the fuel gas or the oxidant can participate in a reaction within the cell stack. The second and fourth main passages MP2 and MP4 are, for example, configured to guide anode off-gas or cathode off-gas generated in the stack to exit the stack.

As shown in fig. 4A and 4B, the end plate body 1 may be formed with a first circulation bypass passage RP1 connecting the external inlet 11 and the second opening 14, the first circulation bypass passage RP1 forming a bypass passage of the third main passage MP3 and having a smaller minimum through-flow sectional area than the third main passage MP3, the first circulation bypass passage RP1 being in an open state when the rack and pinion mechanism 2 is in the first operating state. It is to be understood that "minimum flow cross-sectional area" of the passage means the flow cross-sectional area of the section of the passage where the flow cross-sectional area is smallest in the open state. The minimum flow cross-sectional area of the first circulation bypass passage RP1 is, for example, less than 50%, preferably 30%, particularly 10%, of the minimum flow cross-sectional area of the third main passage MP3, and this ratio can be set according to the specific application. Optionally, the first recirculation bypass passage RP1 has a variable minimum cross-sectional flow area, which can be varied as desired. The opening degree of a specific section of the first circulation bypass passage RP1 can be changed, for example, by means of the rack and pinion mechanism 2 to change the minimum flow-through sectional area of the first circulation bypass passage RP 1.

Here, the first fluid flows from the external inlet 11 into the end plate and flows through the second opening 14 toward the battery cell, and the second fluid from the battery cell mostly flows through the second opening 14 toward the external outlet 12 and is discharged. Another part of the second fluid will be collected into the first fluid flowing from the external inlet 11 toward the battery cell through the first circulation bypass passage RP1 and be reintroduced into the battery cell. Thus, "exhaust gas circulation" can be achieved by the structure of the end plate. This is particularly advantageous where the first fluid is an oxidant. The second fluid flowing out of the cell is generally high in humidity, and the first fluid (oxidant) can be humidified by bringing a part of the second fluid into the first fluid. The second fluid flowing out of the cell unit is generally lower in oxidant concentration, and the merging of a portion of the second fluid into the first fluid (oxidant) also reduces the oxide concentration in the first fluid, thereby reducing the voltage of the fuel cell. Particularly when the fuel cell is operated in a low current operating state, excessive voltages can be avoided. When the fuel cell performs a cold start, the fuel cell is thereby also operated at a desired low voltage, and the exhaust gas residual heat is fully utilized. By means of the first recirculation bypass RP1 and/or the second recirculation bypass RP2, a so-called "reactant starvation" effect can be achieved in a simple manner.

Fig. 5A schematically shows in a cross-sectional view an end plate according to an exemplary embodiment of the invention, wherein the rack and pinion mechanism 2 is in a second operational state. Fig. 5B shows the end plate shown in fig. 5A in a cross-sectional view, wherein the second plate 16 is not shown for clarity.

As shown in fig. 5A and 5B, the end plate body 1 may be formed with a second circulation bypass passage RP2 connecting the external inlet 11 and the first opening 13, the second circulation bypass passage RP2 forming a bypass passage of the first main passage MP1 and having a smaller minimum flow-through sectional area than the first main passage MP1, the second circulation bypass passage RP2 being in an open state when the rack and pinion mechanism 2 is in the second operating state. The minimum flow cross-sectional area of the second recirculation bypass RP2 is, for example, less than 50%, preferably 30%, in particular 10%, of the minimum flow cross-sectional area of the first main passage MP1, which ratio can be set according to the specific application. Alternatively, the second circulation bypass passage RP2 has a variable minimum flow cross-sectional area, which can be varied as desired. The opening degree of a specific section of the second circulation bypass passage RP2 can be changed, for example, by means of the rack and pinion mechanism 2 to change the minimum flow-through sectional area of the second circulation bypass passage RP2.

It can be seen that, when the rack and pinion mechanism 2 is in the second operating state, a part of the second fluid flowing out from the battery unit is merged into the first fluid flowing from the external inlet 11 toward the battery unit through the second circulation bypass passage RP2 and is reintroduced into the battery unit.

By the first circulation bypass passage RP1 and the second circulation bypass passage RP2, the "circulation of exhaust gas" can be realized regardless of whether the rack and pinion mechanism 2 is in the first operating state or the second operating state.

In further embodiments, the end plate body 1 may also be provided with only one of the first circulation bypass passage RP1 and the second circulation bypass passage RP2.

Fig. 4C schematically shows a partial enlarged view of fig. 4A. As shown in fig. 4A and 4C, the end plate includes: the first blocking mechanism 3 is matched with the rack and pinion mechanism 2, so that the first blocking mechanism 3 blocks the first circulation bypass channel RP1 when the rack and pinion mechanism 2 is in the second operation state, and the rack and pinion mechanism 2 can drive the first blocking mechanism 3 to open the first circulation bypass channel RP1 when the rack and pinion mechanism 2 is in the first operation state; and/or a second blocking mechanism 4, wherein the second blocking mechanism 4 is matched with the rack and pinion mechanism 2, so that the second blocking mechanism 4 blocks the second circulation bypass channel RP2 when the rack and pinion mechanism 2 is in the first operation state, and the second blocking mechanism 4 can be driven to open the second circulation bypass channel RP2 by opening the rack and pinion mechanism 2 when the rack and pinion mechanism 2 is in the second operation state. Thereby, it is possible to prevent a part of the first fluid from being undesirably sucked back through the second circulation bypass passage RP2 and the first circulation bypass passage RP1, respectively, when the rack and pinion mechanism 2 is in the first operating state and the second operating state.

Alternatively, the rack and pinion mechanism 2 can selectively cause the first blocking mechanism 3 to open or block the first circulation bypass passage RP1 when the rack and pinion mechanism 2 is in the first operating state, and/or the rack and pinion mechanism 2 can selectively cause the second blocking mechanism 4 to open or block the second circulation bypass passage RP2 when the rack and pinion mechanism 2 is in the second operating state. The "exhaust gas circulation" enabled state can thereby be made relatively independent of the state transition of the rack and pinion mechanism 2. For example, when the rack and pinion mechanism 2 is in the first operating state, the first blocking mechanism 3 may not be driven to open the first circulation bypass passage RP1, so that both the first circulation bypass passage RP1 and the second circulation bypass passage RP2 remain blocked. Accordingly, "exhaust gas recirculation" is not enabled.

Alternatively, the first blocking mechanism 3 and the second blocking mechanism 4 each comprise a recess 31 formed in the end body and a blocking piece 32 connected to the end plate body 1 at the edge of the recess 31 in a hinged manner. A first end of the blocking member 32 remote from the recess 31 is arranged to be able to close the corresponding first circulation bypass passage RP1 or second circulation bypass passage RP2, and a second end of the blocking member 32 near the recess 31 is arranged to be able to be pushed into the recess 31 by the rack and pinion mechanism 2, so that the blocking member 32 rotates and the first end of the blocking member 32 opens the corresponding first circulation bypass passage RP1 or second circulation bypass passage RP2. The blocking member 32 can be returned to a position blocking the corresponding first circulation bypass passage RP1 or second circulation bypass passage RP2, for example, by a spring. Thereby, it is possible to realize the operation of the first and second blocking mechanisms 3 and 4 by the rack and pinion mechanism 2 with a simple and reliable structure.

The recess 31 of the first blocking means 3 may be provided on the side wall of the third channel in alignment with the second rack 23, so that the second rack 23 can protrude into the recess 31 of the first blocking means 3. The recess 31 of the second blocking means 4 can be arranged on the side wall of the first channel in alignment with the first toothed rack 22, so that the second toothed rack 23 can project into the recess 31 of the second blocking means 4.

In an exemplary embodiment according to the present invention, the end plate includes a jet pump 5 at the external inlet 11, the jet pump 5 being arranged to be able to suck the second fluid flowing from the first circulation bypass passage RP1 or the second circulation bypass passage RP2 to the external inlet 11 with energy of the first fluid flowing from the external opening as a power source, so that the sucked second fluid flows toward the battery cells of the battery stack together with the first fluid. Therefore, no additional power source is needed to realize the exhaust circulation.

In this embodiment, the ejector pump 5 includes a contraction section and a diffusion section through which the fluid flows, and the first circulation bypass passage RP1 and the second circulation bypass passage RP2 are laterally connected to one end of the contraction section toward the diffusion section, respectively. The ejector pump 5 may be designed in other forms, and the present invention is not limited thereto as long as the function of the ejector pump 5 can be realized.

The ejector pump 5 may comprise an insert 52 partially inserted in the external inlet 11, said insert 52 comprising a cylindrical body 521 forming at least a constriction of the ejector pump 5 and a stop portion 522 projecting radially outwards from the periphery of the cylindrical body 521, said stop portion 522 being arranged so as to be able to prevent displacement of the insert 52 inside the external inlet 11. Alternatively, the ejector pump 5 may be integrally formed in the end plate body 1, i.e., constituted only by the end plate body 1 without additional components, thereby further simplifying the structure.

The barrel 521 of the insert 52 may comprise an outer section 523 located outside the outer inlet 11, said outer section 523 having a connection, for example a threaded connection, for connection with a conduit supplying the first fluid. Thereby, the connection of the end plate to other components can be facilitated.

In one exemplary embodiment according to the present invention, the end plate body 1 is further formed with: a first dilution bypass passage DP1 connecting the outer outlet 12 and the first opening 13, the first dilution bypass passage DP1 forming a bypass passage of the fourth main passage MP4, the first dilution bypass passage DP1 being in an open state when the rack and pinion mechanism 2 is in the first operating state; and/or a second dilution bypass passage DP2 connecting the outer outlet 12 and the second opening 14, the second dilution bypass passage DP2 forming a bypass passage of the second main passage MP2, the second dilution bypass passage DP2 being in an open state when the rack and pinion mechanism 2 is in the second operating state. Thereby, a portion of the first fluid may be introduced into the second fluid to be discharged, thereby diluting the second fluid. Take the first fluid as the oxidant and the second fluid as the cathode exhaust gas as an example. By introducing an oxidant (e.g., fresh air) into the cathode off-gas to be discharged, the cathode off-gas can be diluted with the oxidant to reduce the hydrogen content in the cathode off-gas, thereby improving safety.

The end plate may include a third blocking mechanism for the first dilution bypass passage DP1 and a fourth blocking mechanism for the second dilution bypass passage DP 2. The third blocking mechanism and the fourth blocking mechanism may have the same mechanism as the first blocking mechanism 3 and the second blocking mechanism 4. It should be understood that the third and fourth blocking mechanisms are not required. However, the third blocking mechanism and the fourth blocking mechanism are arranged to be beneficial to enable the end plate to have a central symmetrical configuration, which is beneficial to saving production and assembly cost.

Although specific embodiments of the invention have been described herein in detail, they have been presented for purposes of illustration only and are not to be construed as limiting the scope of the invention. Various substitutions, alterations, and modifications may be devised without departing from the spirit and scope of the present invention.

List of reference numerals

1. End plate main body

11. External inlet

12. External outlet

13. First opening

14. Second opening

15. First plate

16. Second plate

MP1 first main channel

MP2 second main channel

MP3 third main channel

MP4 fourth main channel

RP1 first circulation bypass channel

RP2 second circulation bypass channel

DP1 first dilution bypass

DP2 second dilution bypass channel

2. Gear rack mechanism

21. Gear wheel

22. First rack

23. Second rack

3. First blocking mechanism

31. Concave part

32. Blocking piece

4. Second blocking mechanism

5. Ejector pump

52. Insert piece

521. Barrel body

522. Position limiting part

523. Outer section

Claims (16)

1. An end plate of a fuel cell for arrangement at one end of a stack of fuel cells, wherein the end plate comprises:

an end plate main body (1) formed with:

an external inlet (11) for introducing a first fluid into the stack and an external outlet (12) for discharging a second fluid from the stack; and

a first opening (13) and a second opening (14) for connection to a battery cell of a battery stack; and

a rack and pinion mechanism (2) having a first operating state and a second operating state, wherein the rack and pinion mechanism (2) is configured such that in the first operating state the external inlet (11) is connected to the first opening (13) and the external outlet (12) is connected to the second opening (14); in a second operating state, the outer inlet (11) is connected to the second opening (14) and the outer outlet (12) is connected to the first opening (13).

2. The end plate of claim 1,

the end plate body (1) is formed with a first main passage (MP 1) connecting the external inlet (11) and the first opening (13), a second main passage (MP 2) connecting the external outlet (12) and the second opening (14), a third main passage (MP 3) connecting the external inlet (11) and the second opening (14), and a fourth main passage (MP 4) connecting the external outlet (12) and the first opening (13), wherein,

in a first operating state, the rack and pinion mechanism (2) opens the first main passage (MP 1) and the second main passage (MP 2), and closes the third main passage (MP 3) and the fourth main passage (MP 4);

in the first operating state, the rack and pinion mechanism (2) closes the first main passage (MP 1) and the second main passage (MP 2), and opens the third main passage (MP 3) and the fourth main passage (MP 4).

3. The end plate of claim 2,

the rack and pinion mechanism (2) comprises a gear (21), a first rack (22) and a second rack (23), wherein:

the first rack (22) and the second rack (23) can be driven by the gear (21) to reciprocate, so that the gear rack mechanism (2) is switched between a first operation state and a second operation state; and/or

In a first operating state of the rack and pinion mechanism (2), the first rack (22) is at least partially located in the fourth main channel (MP 4) and blocks the fourth main channel (MP 4), the second rack (23) is at least partially located in the third main channel (MP 3) and blocks the third main channel (MP 3); and/or

In a second operating state of the rack and pinion mechanism (2), the first toothed rack (22) is located at least partially in the first main channel (MP 1) and blocks the first main channel (MP 1), and the second toothed rack (23) is located at least partially in the second main channel (MP 2) and blocks the second main channel (MP 2).

4. The end plate of claim 2 or 3,

the first main channel (MP 1) and the third main channel (MP 3) are configured for guiding a first fluid such that the first fluid can participate in reactions or heat exchanges within the cell stack, and the second main channel (MP 2) and the fourth main channel (MP 4) are configured for guiding a second fluid out of the cell stack.

5. The end plate of claim 4,

the first fluid is an oxidant and the second fluid is a cathode exhaust gas generated by the stack.

6. The end plate of any of claims 2-5,

the end plate main body (1) is further formed with:

a first circulating bypass passage (RP 1) connecting the external inlet (11) and the second opening (14), the first circulating bypass passage (RP 1) forming a bypass passage of the third main passage (MP 3) and having a smaller minimum flow cross-sectional area than the third main passage (MP 3), the first circulating bypass passage (RP 1) being in an open state when the rack and pinion mechanism (2) is in the first operating state;

a second circulating bypass passage (RP 2) connecting the external inlet (11) and the first opening (13), the second circulating bypass passage (RP 2) forming a bypass passage of the first main passage (MP 1) and having a smaller minimum flow cross-sectional area than the first main passage (MP 1), the second circulating bypass passage (RP 2) being in an open state when the rack and pinion mechanism (2) is in the second operating state.

7. The end plate of claim 6,

the end plate includes:

the first blocking mechanism (3) is matched with the rack and pinion mechanism (2), so that the first blocking mechanism (3) blocks the first circulation bypass channel (RP 1) when the rack and pinion mechanism (2) is in the second operation state, and the rack and pinion mechanism (2) can drive the first blocking mechanism (3) to open the first circulation bypass channel (RP 1) when the rack and pinion mechanism (2) is in the first operation state;

and the second blocking mechanism (4) is matched with the gear rack mechanism (2), so that the second blocking mechanism (4) blocks the second circulation bypass channel (RP 2) when the gear rack mechanism (2) is in the first operation state, and the second blocking mechanism (4) can be driven to open the second circulation bypass channel (RP 2) by opening the gear rack mechanism (2) when the gear rack mechanism (2) is in the second operation state.

8. The end plate of claim 7,

the rack and pinion mechanism (2) is arranged to enable the first blocking mechanism (3) to selectively open or block the first circulation bypass passage (RP 1) in a first operating state; and/or

The rack and pinion mechanism (2) is arranged to enable the second blocking mechanism (4) to selectively open or block the second circulation bypass passage (RP 2) in the second operating state.

9. The end plate of claim 8,

the first blocking means (3) and the second blocking means (4) each comprise a recess (31) formed in the end body and a blocking piece (32) connected to the end plate body (1) in a hinged manner at the edge of the recess (31), wherein a first end of the blocking piece (32) remote from the recess (31) is arranged to be able to close the respective first or second circulation bypass channel (RP 1, RP 2), and a second end of the blocking piece (32) close to the recess (31) is arranged to be able to be pushed into the recess (31) by the rack and pinion mechanism (2), such that the blocking piece (32) rotates and such that the first end of the blocking piece (32) opens the respective first or second circulation bypass channel (RP 1, RP 2).

10. The end plate of any of claims 6-9,

the end plate comprises a jet pump (5) at the external inlet (11), the jet pump (5) being arranged to be able to suck the second fluid flowing from the first circulation bypass passage (RP 1) or the second circulation bypass passage (RP 2) to the external inlet (11) with the energy of the first fluid as a power source, so that the sucked second fluid flows together with the first fluid towards the battery cells of the battery stack.

11. The end plate of claim 10,

the jet pump (5) comprises an insert (52) partially inserted into the external inlet (11), said insert (52) comprising a barrel (521) forming at least a constriction of the jet pump (5).

12. The end plate of claim 11,

the insert (52) further comprises a stopper portion (522) projecting radially outwards from the outer periphery of the cylinder (521), the stopper portion (522) being arranged so as to be able to prevent the insert (52) from being displaced inwards of the external inlet (11); and/or

The barrel (521) of the insert (52) comprises an external section (523) located outside the external inlet (11), said external section (523) having a connection structure for connection with a conduit supplying the first fluid.

13. The end plate of any of claims 2-12,

the end plate body (1) is further formed with:

a first dilution bypass channel (DP 1) connecting the outer outlet (12) with the first opening (13), the first dilution bypass channel (DP 1) forming a bypass channel of the fourth main channel (MP 4), the first dilution bypass channel (DP 1) being in an open state when the rack and pinion mechanism (2) is in the first operating state;

a second dilution bypass channel (DP 2) connecting the outer outlet (12) with the second opening (14), the second dilution bypass channel (DP 2) forming a bypass channel of the second main channel (MP 2), the second dilution bypass channel (DP 2) being in an open state when the rack and pinion mechanism (2) is in the second operational state.

14. The end plate of any of claims 1-13,

the end plate body (1) comprises a first plate (15) and a second plate (16) stacked on each other, the rack and pinion mechanism (2) being arranged between the first plate (15) and the second plate (16).

15. The end plate of any of claims 1-14,

the end plate includes at least one of:

a motor for driving the gear rack mechanism (2), the gear rack mechanism (2) being drivable by the motor to effect a transition between a first operating state and a second operating state;

a manual drive unit for driving the rack and pinion mechanism (2), the manual drive unit being arranged at least partially outside the end plate body (1) such that the rack and pinion mechanism (2) can be manually driven to effect a transition between the first and second operating states.

16. A stack of fuel cells, wherein the stack comprises two end plates and at least one cell unit arranged between the end plates, at least one of the end plates being an end plate according to any of claims 1-15.

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