Fuel cell shutdown system

Abstract

This invention relates to a fuel cell shut-off valve (36) having a valve shut-off body (5) that can be electromagnetically moved from a first state to a second state by energizing an electric coil (10) to close or release at least one medium passage of the fuel cell. To optimize the operation of the fuel cell system, the fuel cell shut-off valve (36) includes two permanent magnets (13, 14), which allow the valve shut-off body (5) to be held in both the first and second states when the electric coil (10) is de-energized.

Description

Technical Field

[0001] This invention relates to a fuel cell shut-off system having a valve shut-off body that can be electromagnetically moved from a first state to a second state by energizing an electric coil, thereby closing or releasing at least one medium passage of the fuel cell. The invention also relates to a method for operating such a fuel cell shut-off valve. Furthermore, the invention relates to a fuel cell system having at least one such fuel cell shut-off valve. Finally, the invention relates to a method for operating such a fuel cell system. Background Technology

[0002] A fuel cell control valve is known from German publication DE 10 2007 039 466 A1. The fuel cell control valve has a body having a channel defined by an inner surface and extending through the inner surface. The fuel cell control valve has a movable part for closing the channel. A fuel cell stack is known from German publication DE 10 2014 204 230 A1. The fuel cell stack has a cathode valve that is coupled to the outlet of the fuel cell stack to control the flow of the cathode stream to the fuel cell stack. A fuel cell system with a fuel cell stack is known from German publication DE 10 2015 011 275 A1. The fuel cell stack includes an anode and a cathode, wherein a shut-off device is arranged in the exhaust pipe of the cathode. A valve for a fuel cell system is known from European Patent Document EP 2 126 435 B1. The valve has a housing including an inlet channel, an outlet channel, and a valve body disposed within the housing and having a liquid intermediate channel providing a liquid connection between the inlet channel and the outlet channel. A valve for a fuel cell system is known from German Publication DE 10 2012 210 022 A1. The valve includes a body having a channel and a displacement element allowing liquid flow through the channel, the displacement element being disposed within the body. A method for generating a gas depleted of oxygen in a fuel cell system is known from German Publication DE 10 2010 053 632 A1, wherein a cathode exhaust valve is closed and the compressor is shut off. Summary of the Invention

[0003] The objective of this invention is to optimize the operation of fuel cell systems.

[0004] In a fuel cell shutdown system, the system includes a valve shut-off body that can be electromagnetically moved from a first state to a second state by energizing an electric coil, thereby closing or releasing at least one medium passage of the fuel cell. This task is accomplished by the fuel cell shutdown valve comprising two permanent magnets, which allow the valve shut-off body to be held in either the first or second state in the absence of current in the electric coil. The fuel cell shutdown valve is advantageously used to close the cathode side of the fuel cell as needed during operation of the fuel cell system equipped with the valve. This, for example, prevents oxygen from diffusing from the surrounding environment above the diaphragm of the fuel cell cathode to the anode. Depending on whether such a fuel cell shutdown valve is used, and if so, how many, the pre-described diffusion process can last for hours or days. Once air is present at the anode of the fuel cell, an air / air start-up is involved during fuel cell restart. Here, a very high potential difference is generated in the fuel cell. This potential difference leads to severe aging of the fuel cell catalyst. The claimed fuel cell shutdown system minimizes the number of air / air starts during the lifespan of the fuel cell. For this purpose, it is advantageous to arrange one fuel cell shut-off valve at the cathode inlet and another fuel cell shut-off valve at the cathode outlet of the fuel cell. The fuel cell shut-off valve is particularly advantageous in rare cases to achieve desired air / air start-up, utilizing a high potential difference to, for example, eliminate poisoning of the catalyst located in the fuel cell. The claimed fuel cell shut-off valve is simply constructed and can be cost-effectively manufactured. The fuel cell shut-off valve can advantageously be held in the open and closed positions without current by means of two permanent magnets.

[0005] A preferred embodiment of the fuel cell shut-off valve is characterized in that a valve shut-off body is combined with a guide rod on which a permanent magnet is mounted. The guide rod is advantageously used to guide the valve shut-off body reciprocating between two positions in which the valve shut-off body can occupy during operation of the fuel cell shut-off valve. Corresponding guide channels for the guide rod can be easily provided within the housing body of the fuel cell shut-off valve housing.

[0006] Another preferred embodiment of the fuel cell shut-off valve is characterized in that the valve shut-off body is implemented as a valve disc. The valve disc allows for the simple closing or opening of the relatively large media passage of the fuel cell. The valve disc is particularly advantageously mounted on the end of a guide rod. According to the embodiment, it is advantageous to connect the valve disc and the guide rod in a single piece.

[0007] Another preferred embodiment of the fuel cell shut-off valve is characterized in that the valve disc is equipped with a first seal and a second seal, the valve disc being sealingly abutting against the first seal in a first position and sealingly abutting against the second seal in a second position. The seals are advantageously implemented, for example, as O-ring seals.

[0008] In the method for operating the fuel cell shut-off valve described above, the aforementioned task is alternatively or additionally addressed by reversing the polarity of the voltage supply to the coil to switch the fuel cell shut-off valve between a first and a second position. Therefore, the claimed fuel cell shut-off valve can be arbitrarily switched on by energizing the coil, while simultaneously ensuring that the valve shut-off body is held in its current position by a permanent magnet in the absence of current in the coil.

[0009] In a fuel cell system having at least one of the aforementioned fuel cell shut-off valves, the aforementioned task is alternatively or additionally addressed by arranging the fuel cell shut-off valve as a cathode valve in the cathode path. The cathode valve is, for example, implemented as a two-position three-way valve.

[0010] A preferred embodiment of the fuel cell system is characterized in that the fuel cell system includes two cathode paths, each of which is equipped with a fuel cell shut-off valve implemented as a two-position three-way valve, as described above. Through these two two-position three-way valves, the cathode side of the fuel cell can be flowed through in opposite directions in a simple manner.

[0011] Another preferred embodiment of the fuel cell system is characterized by including an additional fuel cell shut-off valve, implemented as a two-position two-way valve, as described above. This additional two-position two-way valve provides, particularly advantageously, the additional function of separating the fuel cell from the ambient air at the fuel cell cathode during operation.

[0012] In the method for operating the fuel cell system described above, the aforementioned task is alternatively or additionally addressed by reversing the flow direction on the cathode side of the fuel cell. This reversal of the flow direction on the cathode side advantageously facilitates fuel cell humidification. The required arrangement of these two fuel cell shut-off valves, advantageously implemented as two-position three-way valves, eliminates the need for an external humidification device.

[0013] The present invention also relates to permanent magnets, valve closing bodies, particularly valve discs, guide rods, and / or coils for use in the fuel cell shut-off valves described above. The aforementioned components can be processed individually if necessary.

[0014] Further advantages, features and details of the present invention will become apparent from the following description, in which different embodiments are described in detail with reference to the accompanying drawings. Attached Figure Description

[0015] In the attached diagram:

[0016] Figure 1 A fuel cell shut-off valve with a valve shut-off body in the first state is shown in longitudinal section;

[0017] Figure 2 Show and Figure 1 The same cross-sectional view, showing the valve closing body in the second position; and

[0018] Figure 3 It shows two as in Figure 1 and 2 The diagram shows a schematic representation of a fuel cell system with a fuel cell shut-off valve. Detailed Implementation

[0019] exist Figure 3 The diagram schematically illustrates a fuel cell system having a fuel cell 30. The fuel cell 30 includes an anode side 31 and a cathode side 32. The fuel cell 30 has an anode inlet 33 and an anode outlet 34 on the anode side 31. The fuel cell 30 is supplied with hydrogen, for example, on the anode side 31. The fuel cell 30 is supplied with oxygen, for example, through a cathode inlet 40, on the cathode side 32, in the form of air.

[0020] As in Figure 3 As seen below the fuel cell 30, three fuel cell shut-off valves 36, 37, and 38 are arranged on the cathode side 32, each marked with a circular symbol. Fuel cell shut-off valves 36 and 37 are implemented as two-position three-way valves. Fuel cell shut-off valve 38 is implemented as a two-position two-way valve.

[0021] exist Figure 3 In the diagram, arrows 41 to 46 and 51 to 57 indicate the first cathode path, which can be generated by fuel cell shut-off valves 36 and 37 (darstellbar). Through the first cathode paths 41 to 46 and 51 to 57, the cathode side 32 of the fuel cell 30 can... Figure 3 The cathode gas flows from left to right through the center.

[0022] exist Figure 3 In the diagram, arrows 61 to 66 and 71 to 77, drawn with dashed lines, indicate the second cathode path. This second cathode path can be achieved through the corresponding switching of fuel cell shut-off valves 36 and 37. The second cathode paths 61 to 66 and 71 to 77 enable the cathode side 32 of fuel cell 30 to... Figure 3 The water flows from right to left through the middle.

[0023] exist Figure 1 and2 The longitudinal section shows in detail Figure 3 The fuel cell shut-off valve 36 in the middle, the fuel cell shut-off valve having a first state ( Figure 1 ) in the second position ( Figure 2 Valve closing body 5 in )

[0024] The fuel cell shut-off valve 36 includes a valve housing 1 having three media channels 2 to 4 converging within the valve housing 1. The valve shut-off body 5 is implemented as a valve disc 6.

[0025] exist Figure 1 In the middle, valve closing body 5 closes the medium channel 3, allowing cathode gas to reach the medium channel 4 from the medium channel 2, as in... Figure 3 As indicated by arrows 43 and 44. Figure 2 In the middle, valve closing body 5 closes the medium channel 2, allowing cathode gas to flow from medium channel 4 to medium channel 3, as in... Figure 3 As indicated by arrows 73 and 74 drawn with dashed lines.

[0026] A valve disc 6 is mounted on the end of a guide rod 7. The guide rod 7 guides the valve closing body 5 within a guide channel 9 of the housing body 8. The housing body 8 is integrally connected to the valve housing 1. An electrical coil 10 is arranged within the housing body 8. The electrical coil 10 surrounds the guide rod 7 within the housing body 8.

[0027] Through symbols 11 and 12 Figure 1 and 2 The specification states that the voltage supply of coil 10 can be polarized as needed.

[0028] Two permanent magnets 13 and 14 are fixed at defined locations on the guide rod 7. (The symbols are used to indicate this.) Figure 1 The text indicates that permanent magnets 13 and 14 have a north pole and a south pole, respectively.

[0029] Furthermore, two seals 15 and 16 are arranged in the valve body 1. The seals 15 and 16 are, for example, implemented as O-rings and received in suitable annular grooves in the valve body 1. Figure 1 In the middle, the valve disc 6 is sealed against the seal 16. Figure 2 In the middle, the valve disc 6 is sealed against the sealing element 15.

[0030] exist Figure 1 and 2 In this configuration, the fuel cell shut-off valve 36 is moved via two permanent magnets 13 and 14 and an electric coil 10. The voltage supply to the electric coil 10 surrounding the ferromagnetic core can selectively switch polarity. This generates an attractive or repulsive magnetic field that acts on the two permanent magnets 13 and 14.

[0031] Guided by the guide rod 7 in the guide channel 9 of the housing body 8, the valve disc 6 can be moved by the polarity change of the coil 10. Figure 1 and 2 The endpoint position is shown in the figure.

[0032] Two fuel cell shut-off valves, implemented as two-position two-way valves, are sufficient to prevent air / air start. This is achieved through... Figures 1 to 3 The two two-position three-way valves 36 and 37 shown advantageously create the possibility of reversing or changing the flow direction on the cathode side 32 of the fuel cell 30, as in Figure 3 As indicated by arrows 41 to 46, 51 to 57, 61 to 66, and 71 to 77.

[0033] The change in flow direction on the cathode side 32 is used, for example, to generate fuel cell humidification. This eliminates the need for external humidification, for example, by using a gas-to-gas humidifier. This change in flow direction on the cathode side 32 for fuel cell humidification primarily occurs in fuel cell vehicles with a sufficiently high degree of hybridization, because the fuel cell cannot produce, or can only produce, reduced power during the change in cathode flow direction. This means that for a short time, such as a few seconds, the drive power must come entirely or at least partially from the traction battery.

[0034] exist Figure 3 In this configuration, the fuel cell shut-off valve 38, preferably implemented as a two-position two-way valve, is advantageously used to separate the cathode side 32 of the fuel cell 30 from ambient air during shutdown. For this purpose, the fuel cell shut-off valve 38 is arranged at the cathode inlet 40. The arrangement of the fuel cell shut-off valve 38 at the cathode inlet 40 is preferred because the risk of product water formation and condensation is minimized in this area of ​​the fuel cell system.

Claims

1. A fuel cell shut-off valve (36; 37; 38) having a valve shut-off body (5) capable of electromagnetically moving from a first state to a second state by energizing an electric coil (10) to close or release at least one medium passage of a fuel cell (30), characterized in that, The fuel cell shut-off valve (36; 37; 38) includes two permanent magnets (13, 14). The valve shut-off body (5) is able to be held in the first position or the second position when the coil (10) is in a state without current by means of the permanent magnets. The valve shut-off body (5) is combined with a guide rod (7), on which the permanent magnets (13, 14) are mounted. The guide rod (7) is guided in the guide channel (9) of the housing body (8). The housing body (8) is integrally connected to the valve housing (1) and arranged in the medium channel of the valve housing (1). The coil (10) is arranged in the housing body (8) and surrounds the guide rod (7) in the housing body (8).

2. The fuel cell shut-off valve according to claim 1, characterized in that, The valve closing body (5) is implemented as a valve disc (6).

3. The fuel cell shut-off valve according to claim 2, characterized in that, The valve disc (6) is equipped with a first seal (16) and a second seal (15). In the first position, the valve disc (6) is sealed against the first seal, and in the second position, the valve disc (6) is sealed against the second seal.

4. A method for operating a fuel cell shut-off valve (36) according to any one of the preceding claims, characterized in that, The voltage supply polarity of the coil (10) is switched so that the fuel cell shut-off valve (36) switches between the first state and the second state.

5. A fuel cell system having a fuel cell shut-off valve (36; 37; 38) according to any one of claims 1 to 3, characterized in that, The fuel cell shut-off valves (36; 37; 38) are arranged as cathode valves in the cathode paths (41-46, 51-57; 61-66, 71-77).

6. The fuel cell system according to claim 5, characterized in that, The fuel cell system (26) includes two cathode paths (41-46, 51-57; 61-66, 71-77), and a fuel cell shut-off valve (36, 37) implemented as a two-position three-way valve is arranged in each cathode path.

7. The fuel cell system according to claim 6, characterized in that, The fuel cell system includes an additional fuel cell shut-off valve (38) implemented as a two-position two-way valve.

8. A method for operating a fuel cell system according to claim 6 or 7, characterized in that, The flow direction on the cathode side (32) of the fuel cell (30) is reversed.

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