Valve device for a fuel cell system, and fuel cell system

Abstract

The invention relates to a valve device for a fuel cell system and to a fuel cell system having such a valve device. The valve device comprises a valve housing, a first valve seat and a second valve seat which has a larger valve diameter than the first valve seat. The valve device further comprises a valve closing body, which is movably guided in the valve housing along a longitudinal axis, wherein the valve closing body is designed to close the first valve seat in a closed state, and a servo piston unit, which is guided so as to be movable along the longitudinal axis relative to the valve closing body and through the valve closing body. The first valve seat is arranged in the servo piston unit, and the servo piston unit and the valve closing body interact in such a way that the second valve seat is closed by the servo piston unit and the valve closing body in a closed state.

Description

[0001] Description

[0002] title

[0003] Valve device for a fuel cell system and fuel cell system

[0004] The present invention relates to a valve device for a fuel cell system. Furthermore, the present invention relates to a fuel cell system with such a valve device.

[0005] State of the art

[0006] Conventional fuel cell systems require atmospheric oxygen and hydrogen for the chemical reaction. A fuel cell consists of an anode and a cathode. During operation, the anode is supplied with hydrogen, and the cathode with the oxidizer, i.e., the oxygen from the air. Many PEM fuel cells have a connection between the stack's anode outlet and inlet. The gas in the anode is recirculated through this connection. This allows unused hydrogen to be returned to the system, increasing efficiency. Furthermore, a metering valve is integrated into the anode circuit to compensate for the hydrogen consumed in the fuel cell, allowing fresh hydrogen to be added. A technical device, typically a pump or fan, is required to maintain this recirculation within the anode circuit.Commonly used pumps include jet pump systems, but also positive displacement pumps or blowers. Combinations are also frequently used. Systems exclusively with a jet pump, so-called jet pump-only systems, represent a very cost-effective and easy-to-operate option. However, such systems have some limitations. The regulation or metering of hydrogen in the anode circuit is usually achieved via one or more metering valves. This allows the desired pressure to be set.

[0007] Additionally, a shut-off valve is often used, connected in series upstream of the metering or control valve. This ensures a reliable shutdown of the hydrogen supply from the tank. The shut-off valve creates a pressure drop, thus reducing the pressure available to the metering valve. Furthermore, the pressure drop of the shut-off valve increases the required operating pressure range of the control valve, thereby reducing its control performance.

[0008] For example, DE 10 2022 200 494 A1 discloses a valve device, such as that used in particular for controlling a gas flow, for example for controlling a gas flow for the supply of gas to a fuel cell in a fuel cell arrangement. With only one such valve device and with only one electric actuator, both the fuel cell stack area can be shut off and a bypass, i.e. the connection to the exhaust system area, can be opened.

[0009] In a fuel cell system, a jet pump is often used in the anode circuit to enable the necessary recirculation of the anode gas.

[0010] The jet pump's drive nozzle requires the highest possible pressure to achieve good recirculation performance. A pressure loss in the shut-off valve reduces the pressure at the jet pump and thus the recirculation performance.

[0011] Disclosure of the invention

[0012] The invention provides a valve device for a fuel cell system with the features of claim 1 and a fuel cell system with the features of claim 10. According to a first aspect of the invention, a valve device for a fuel cell system is provided. The valve device comprises a valve housing, a first valve seat, and a second valve seat having a larger valve diameter than the first valve seat. Furthermore, the valve device comprises a valve closing element that is slidably guided in the valve housing along a longitudinal axis, the valve closing element being configured to close the first valve seat in a closed state. The valve device also comprises a servo piston unit that is slidably guided along the longitudinal axis relative to and through the valve closing element.The first valve seat is located in the servo piston unit, and the servo piston unit and the valve closing element work together in such a way that the second valve seat is closed by the servo piston unit and the valve closing element in a closed state.

[0013] According to a second aspect of the invention, a fuel cell system is provided. The fuel cell system comprises a fuel cell stack with an anode and a cathode, as well as a recirculation circuit for recirculating a recirculation medium at the anode. Furthermore, the fuel cell system includes a fuel line for supplying the fuel cell stack with hydrogen and a metering valve device connected to the fuel line and the recirculation circuit. The fuel cell system also includes a valve device according to the first aspect of the invention, wherein the valve device is connected to the fuel line.

[0014] One of the underlying ideas of the present invention is to provide a valve or valve assembly with a two-stage valve seat, wherein the servo piston unit for the second valve seat is guided on the moving valve closing element of the first valve seat. In this way, a cost-effective design of the valve assembly can be achieved.

[0015] For example, the valve closing element can be designed as a magnetic armature. Furthermore, the valve housing can have at least one bushing for guiding the valve closing element. This bushing can be made of, for example, plastic or a similar material. The valve assembly can also include a magnetic actuator that exerts a magnetic force on the valve closing element designed as a magnetic armature, thereby opening the first valve seat. To close the first and / or second valve seat, the valve closing element can be coupled to a closing spring assembly that is supported in the valve housing. This means that the closing spring assembly acts to close the valve closing element and the first and / or second valve seat.

[0016] The first valve seat, due to its smaller diameter, can be opened with a smaller magnetic actuator. Opening the first valve seat results in flow through it and pressure builds up in the outlet section of the valve assembly. This outlet section can be at least partially enclosed by a nozzle component. Once the pressure in the outlet section reaches the same level as in the inlet section of the valve assembly, the second valve seat is pressure-balanced. In this pressure-balanced state, the second valve seat requires only a small opening force. The open second valve seat allows for a large opening cross-section of the valve assembly. In particular, this enables the valve assembly to exhibit a very low pressure drop.Despite the large opening cross-section, the valve device can be switched with a small magnetic actuator due to the servo piston unit according to the invention.

[0017] The valve device can be used, for example, as a shut-off valve for gaseous substances. Advantageously, the valve device can be used as a shut-off valve in a medium-pressure section of an anode system of a fuel cell.

[0018] The valve device can be controlled by a control unit, in particular by the fuel cell control unit.

[0019] Advantageous embodiments and further developments are described in the dependent claims and in the description with reference to the figures in the drawing. According to a further development of the invention, the servo piston unit at least partially delimits a lower end region of the valve closing element. In this way, the guidance of the servo piston unit by the valve closing element can be designed close to the second valve seat, particularly in the region of the second valve seat. This allows the servo piston unit to align itself with the second valve seat and thus compensate for tolerances. This results in simple and cost-effective manufacturing, which provides high tightness and reliability.

[0020] According to a further embodiment of the invention, the servo piston unit has at least one opening for the flow of fuel. Thus, the fuel, in particular hydrogen, can flow from the inlet area to the outlet area of ​​the valve device when the first valve seat is open and the second valve seat is closed. The at least one opening can be arranged on a cylindrical surface of the servo piston unit.

[0021] According to a further embodiment of the invention, the servo piston unit is slidably guided through the valve closing body by means of a guide bushing, wherein the guide bushing is in contact with the servo piston unit on its outer surface and with the valve closing body on its inner surface.

[0022] According to a further embodiment of the invention, the servo piston unit is designed and slidably guided by the valve closing element such that the servo piston unit has a predetermined tilting clearance relative to the valve closing element. The servo piston unit can thus align itself with the second valve seat. In this way, even with a relatively large valve diameter, a plane-parallel position of the second valve seat, and in particular a plane-parallel position of the valve closing element or sealing element with respect to the nozzle component, can be achieved. Thus, a high degree of sealing can be provided with low spring force.

[0023] According to a further embodiment of the invention, the valve device also comprises an opening spring device for opening the second valve seat, wherein the opening spring device is configured to move the servo piston unit in the direction of the valve closing element. Thus, after pressure equalization between the inlet and outlet areas, the second valve seat can be opened by the opening spring device. The opening spring device can be supported against the nozzle component, which may have the outlet of the valve device.

[0024] The nozzle component may also include the second valve seat. The opening spring assembly may have a lower spring force than the closing spring assembly so that both the first and second valve seats are closed when the valve device is deactivated. The opening spring assembly and / or the closing spring assembly may be designed as a helical compression spring or similar.

[0025] According to a further embodiment of the invention, the opening spring device is designed such that the second valve seat remains open during flow.

[0026] According to a further embodiment of the invention, the valve device also comprises a drive mechanism for opening the second valve seat, wherein the drive mechanism is designed and positively connected to the valve closing element and the servo piston unit such that the valve closing element and the servo piston unit interact when the second valve seat is opened. The drive mechanism may have connecting pins that are fixed to the valve closing element and engage in the servo piston unit for a positive connection.

[0027] According to a further embodiment of the invention, the positive-locking connection between the drive unit and the servo piston unit has a free stroke, so that the servo piston unit is driven by the valve closing element after the free stroke. This free stroke allows the first valve seat to be opened with a small magnetic force. After pressure equalization in the outlet area B2, the second valve seat can also be opened with a small magnetic force. Due to the pressure equalization between the inlet area and the outlet area, a closing pressure force on the second valve seat is eliminated.

[0028] Optionally, the valve device can be located upstream of the metering valve assembly in the fuel line. For example, the recirculation medium from the fuel cell stack contains unused hydrogen as well as uncollected nitrogen.

[0029] Brief description of the drawings

[0030] The invention will now be explained with reference to the figures in the drawings. The figures show:

[0031] Fig. 1 shows a schematic view of a fuel cell system according to an embodiment of the invention;

[0032] Fig. 2 shows a schematic sectional view of a valve device for a fuel cell system according to a further embodiment of the invention; and

[0033] Fig. 3 shows a schematic sectional view of a valve device for a fuel cell system according to a further embodiment of the invention.

[0034] In the figures, the same reference symbols denote identical or functionally equivalent components, unless otherwise stated. The numbering of process steps is for clarity and generally does not imply a specific chronological order. In particular, several process steps can be performed simultaneously.

[0035] Description of the exemplary implementations

[0036] Further advantages, features, and details of the invention will become apparent from the following description, in which various embodiments are described in detail with reference to the drawing. Fig. 1 shows a schematic view of a fuel cell system 10 according to an embodiment of the invention. In particular, an anode system of the fuel cell system 10 is shown.

[0037] The fuel cell system 10 comprises, by way of example, a fuel cell stack 11. The fuel cell stack 11 has an anode 11a and a cathode 11b. The fuel cell system 10 also includes a recirculation circuit 12 for recirculating a recirculation medium at the anode 11a. The anode 11a is supplied with hydrogen via a fuel line 13. At the inlet of the fuel line 13, for example, there is a high-pressure tank and a pressure regulating valve. Further components can be arranged in the fuel line 13 to supply the anode 11a of the fuel cell stack 11 with fuel as needed. Excess fuel, as well as certain flow rates of water and nitrogen that diffuse through the cell membranes onto the anode 11a, are returned to the recirculation circuit 12 and mixed with the metered fuel from the fuel line 13.

[0038] Furthermore, the fuel cell system 10 includes, by way of example, a metering valve assembly 14, which is connected to the fuel line 13 and to the recirculation circuit 12. The metering valve assembly 14 is arranged at a transition between the fuel line 13 and the recirculation circuit 12.

[0039] Various components, such as a jet pump 17 and / or a recirculation blower 21, can be installed to drive the flow in the recirculation circuit 12.

[0040] Furthermore, in the anode system, for example, a pressure regulator 18 is arranged upstream of the metering valve device 14, i.e. in the fuel line 13, and a pressure measurement 19 is arranged in the anode system.

[0041] The metering valve assembly 14 meters the hydrogen, thereby regulating the pressure of the anode system of the fuel cell system 10. Water, hydrogen, and / or nitrogen can be drained from the recirculation circuit 12 via a drain valve 20. For example, the metering valve assembly 14 can be a hydrogen metering valve or a proportional valve. Alternatively, the metering valve assembly can be configured as either a hydrogen metering valve or a proportional valve.

[0042] Furthermore, the fuel cell system 10 comprises a valve assembly 1. The valve assembly 1 includes a valve housing, a first valve seat, and a second valve seat. The second valve seat has a larger valve diameter than the first valve seat. The valve assembly 1 also includes a valve closing element, which is slidably guided in the valve housing along a longitudinal axis. The valve closing element is designed to close the first valve seat in a closed state. The valve assembly 1 further includes a servo piston unit, which is slidably guided along the longitudinal axis relative to and through the valve closing element. The first valve seat is located in the servo piston unit. The servo piston unit and the valve closing element interact such that the second valve seat is closed by the servo piston unit and the valve closing element in a closed state.

[0043] Furthermore, the fuel cell system 10 can, for example, include a control device 15, in particular a fuel cell control unit (not shown), which is connected to the metering valve device 14 and / or the valve assembly 1. The control device 15 can be configured to provide pilot control of a control current for the metering valve device 14 or may include a pilot control unit 16 for pilot control of the control current.

[0044] Fig. 2 shows a schematic sectional view of a valve device 1 for a fuel cell system 10 according to a further embodiment of the invention.

[0045] The valve device 1 comprises a valve housing K1, a first valve seat S1, and a second valve seat S2. The second valve seat S2 has a larger valve diameter than the first valve seat S1. For example, the valve closing element K2 can be designed as a magnetic armature.

[0046] Furthermore, the valve device 1 comprises a valve closing element K2, which is slidably guided in the valve housing K1 along a longitudinal axis X. The valve closing element K2 is designed to close the first valve seat S1 in a closed state. The valve housing K1 can also have at least one bushing K4 for guiding the valve closing element K2. The at least one bushing K4 can be made of, for example, plastic or the like. The valve device 1 can also include a magnetic actuator K3, which acts magnetically on the valve closing element K2, designed as a magnetic armature, and can thus open the first valve seat S1. To close the first and / or second valve seat S1, S2, the valve closing element K2 can be coupled to a closing spring device F1, which is supported in the valve housing K1.This means that the closing spring device F1 acts to close the valve closing element K2 and the first and / or second valve seat.

[0047] The first valve seat S1 can be opened with a smaller magnetic actuator due to its smaller valve diameter. When the first valve seat S1 opens, flow occurs through it, and pressure builds up in a discharge area B2 of the valve device 1. Once the pressure in the discharge area B2 equals that in an inlet area B1 of the valve device, the second valve seat S2 is pressure-balanced. In this pressure-balanced state, the second valve seat S2 requires only a small opening force. The open second valve seat S2 allows for a large opening cross-section of the valve device. In particular, the valve device 1 can thus exhibit a very low pressure drop. Despite the large opening cross-section, the valve device can be switched with a small magnetic actuator thanks to the servo piston unit K10 according to the invention.

[0048] Furthermore, the valve device 1 comprises a servo piston unit K10, which is guided slidably along the longitudinal axis X relative to and through the valve closing element K2. The first valve seat S1 is arranged in the servo piston unit K10. The servo piston unit K10 and the valve closing element K2 interact such that the second valve seat S2 is closed by the servo piston unit K10 and the valve closing element K2 in a closed state. For example, the servo piston unit K10 at least partially encloses a lower end region of the valve closing element K2, as illustrated in Fig. 2. In this way, the guidance of the servo piston unit through the valve closing element can be designed close to the second valve seat, particularly in the region of the second valve seat S2. This allows the servo piston unit K10 to align itself with the second valve seat S2 and thus compensate for tolerances.

[0049] Optionally, the servo piston unit K10 can have at least one opening 2 for the flow of fuel. Thus, the fuel, in particular hydrogen, can flow from the inlet area B1 to the outlet area B2 of the valve device when the first valve seat S1 is open and the second valve seat S2 is closed. The at least one opening 2 can be arranged on a surface of the servo piston unit. Figure 2 shows, by way of example, two openings 2 arranged opposite each other on the surface of the servo piston unit.

[0050] The servo piston unit K10 can be slidably guided through the valve closing element K2 by means of a guide bushing K12, wherein the guide bushing K12 is in contact with the servo piston unit K10 on its outer surface and with the valve closing element K2 on its inner surface. For example, the servo piston unit K10 can be designed and slidably guided through the valve closing element K2 such that the servo piston unit K10 has a predetermined tilting clearance relative to the valve closing element K2. The servo piston unit K10 can thus align itself with the second valve seat S2. In this way, even with a relatively large valve diameter, a plane-parallel position of the second valve seat S2, and thus in particular a plane-parallel position of the valve closing element or sealing element K2 with respect to the nozzle component K11, can be achieved.

[0051] By way of example, the valve device 1 here comprises an opening spring assembly F2 for opening the second valve seat S2, wherein the opening spring assembly F2 is configured to move the servo piston unit K10 towards the valve closing element K2. Thus, after pressure equalization between the inlet area B1 and the outlet area B2, the second valve seat S2 can be opened by the opening spring assembly F2. The opening spring assembly F2 can be supported against the nozzle component K11, which can have the outlet of the valve device 1.

[0052] The nozzle component K1 can further include the second valve seat S2. The opening spring assembly F2 can have a lower spring force than the closing spring assembly F1, so that the first valve seat S1 and the second valve seat S2 are closed when the valve device is deactivated. The opening spring assembly F2 can be designed such that the second valve seat S2 remains open during flow.

[0053] The first valve seat S1 or the second valve seat S2 or both valve seats S1, S2 can be designed as a flat seat in the servo piston unit K10 and equipped with a

[0054] Elastomeric seal K5 interacts with the valve closing element K2. The elastomeric seal K5 can, for example, be positioned on an end face of the lower end region of the valve closing element K2. To increase the tightness, the first and / or second valve seat S1, S2 can have a sealing edge.

[0055] Fig. 3 shows a schematic sectional view of a valve device 1 for a fuel cell system 10 according to a further embodiment of the invention.

[0056] The valve device 10 shown here as an example has essentially the same features as the valve device 10 according to Fig. 2, wherein here the servo piston unit K10 is opened by a drive device K20 from the valve closing body K2 instead of the opening spring device F2.

[0057] The drive mechanism K20 can be configured, in particular, to open the second valve seat S2. Furthermore, the drive mechanism K20 can be configured and positively connected to the valve closing element K2 and the servo piston unit K10 such that the valve closing element K2 and the servo piston unit K10 interact when the second valve seat S2 is opened. The drive mechanism K20 can have connecting pins K30 that are fixed to the valve closing element K2 and engage in the servo piston unit K10 to form a positive connection.

[0058] The positive-locking connection between the drive unit K20 and the servo piston unit K10 can, for example, have a free stroke H1, so that the servo piston unit K10 is driven by the valve closing element K2 after the free stroke H1. The free stroke H1 thus allows the first valve seat S1 to be opened with a small magnetic force. After pressure equalization in the outlet area B2, the second valve seat S2 can also be opened with a small magnetic force. Due to the pressure equalization between the inlet area B1 and the outlet area B2, a closing pressure force on the second valve seat S2 is eliminated.

[0059] Although the present invention has been explained above by way of example embodiments, it is not limited to these, but can be modified in many ways. In particular, combinations of the preceding embodiments are also conceivable.

Claims

Claims 1. Valve device (1) for a fuel cell system (10), the valve device (1) comprising: - a valve body (K1); - a first valve seat (S1) and a second valve seat (S2) which has a larger valve diameter than the first valve seat (S1); - a valve closing element (K2) which is slidably guided in the valve housing (K1) along a longitudinal axis (X), wherein the valve closing element (K2) is configured to close the first valve seat (S1) in a closed state; and - a servo piston unit (K10) which is guided displaceably along the longitudinal axis (X) relative to the valve closing element (K2) and through the valve closing element (K2), wherein the first valve seat (S1) is arranged in the servo piston unit (K10), and wherein the servo piston unit (K10) and the valve closing element (K2) interact in such a way that the second valve seat (S2) is closed in a closed state by the servo piston unit (K10) and the valve closing element (K2).

2. Valve device according to claim 1, wherein the servo piston unit (K10) at least partially delimits a lower end region of the valve closing body (K2).

3. Valve device according to claim 1 or 2, wherein the servo piston unit (K10) has at least one opening (2) for the flow of fuel.

4. Valve device according to one of the preceding claims, wherein the servo piston unit (K10) is slidably guided through the valve closing body (K2) by means of a guide bushing (K12), wherein the guide bushing (K12) is in contact with the servo piston unit (K10) at its outer surface and is in contact with the valve closing body (K2) at its inner surface.

5. Valve device according to one of the preceding claims, wherein the servo piston unit (K10) is designed and guided displaceably by the valve closing body (K2) such that the servo piston unit (K10) has a predetermined tilting clearance relative to the valve closing body (K2).

6. Valve device according to one of the preceding claims, further comprising an opening spring device (F2) for opening the second valve seat (S2), wherein the opening spring device (F2) is configured to move the servo piston unit (K10) in the direction of the valve closing body (K2).

7. Valve device according to claim 6, wherein the opening spring device (F2) is designed such that the second valve seat (S2) remains open during flow.

8. Valve device according to one of the preceding claims, further comprising a drive device (K20) for opening the second valve seat (S2), wherein the drive device (K20) is designed and positively connected to the valve closing body (K2) and the servo piston unit (K10) such that the valve closing body (K2) and the servo piston unit (K10) cooperate when opening the second valve seat (S2).

9. Valve device according to claim 8, wherein the positive locking connection between the drive device (K20) and the servo piston unit (K10) has a free stroke (H1) so that the servo piston unit (K10) is carried along by the valve closing element (K2) after the free stroke (H1).

10. Fuel cell system (10) comprising: - a fuel cell stack (11) with an anode (11a) and a cathode (11b); - a recirculation circuit (12) for recirculating a recirculation medium at the anode (11a); - a fuel line (13) for supplying the fuel cell stack (11) with a fuel, in particular hydrogen; - a metering valve device (14) which is connected to the fuel line (13) and to the recirculation circuit (12); and - a valve device (1) according to one of the preceding claims, wherein the Valve device (1) is connected to the fuel line (13)

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