Fuel cell system

Abstract

To provide a technique capable of continuously operating a fuel cell system even when abnormality of a valve is detected.SOLUTION: A fuel cell system includes: a fuel cell having a supply port into which an oxidant gas flows and a discharge port from which the oxidant gas flows out; a gas supply pipe connected to the supply port and a gas discharge pipe connected to the discharge port; a pressure sensor that measures gas pressure of the oxidant gas in the fuel cell; a pressure regulating valve that is provided in the gas discharge pipe and regulates gas pressure; and a control unit that controls an opening degree of the pressure regulating valve. The control unit controls the opening degree of the pressure regulating valve to any one of a target opening degree determined according to the gas pressure and a correction opening degree when abnormality occurs in a seal member of the pressure regulating valve and being larger than the target opening degree.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to fuel cell systems. [Background technology]

[0002] BACKGROUND ART Techniques are known that can detect valve abnormalities in fuel cell systems (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-218904 Summary of the Invention [Problem to be solved by the invention]

[0004] There was a need for technology that would allow fuel cell systems to continue operating even when a valve abnormality was detected. [Means for solving the problem]

[0005] The present disclosure has been made to solve the above-mentioned problems, and can be realized in the following forms.

[0006] According to an embodiment of the present disclosure, there is provided a fuel cell system comprising: a fuel cell having a supply port through which an oxidant gas flows and an outlet port through which the oxidant gas flows; a gas supply pipe connected to the supply port; a gas outlet pipe connected to the outlet port; a pressure sensor for measuring the gas pressure of the oxidant gas in the fuel cell; a pressure regulating valve provided in the gas outlet pipe for adjusting the gas pressure; and a control unit for controlling an aperture of the pressure regulating valve. The control unit controls the aperture of the pressure regulating valve to either a target aperture determined according to the gas pressure or a correction aperture greater than the target aperture in case an abnormality occurs in a sealing member of the pressure regulating valve. In this fuel cell system, if an abnormality occurs in the sealing member of the pressure regulating valve, the valve opening is increased, thereby alleviating the stress caused by contact between the valve and the sealing member, and therefore the fuel cell system can be operated while preventing the abnormality from becoming worse.

[0007] The present disclosure can be realized in various forms, for example, as a control unit for a pressure regulating valve, a control method for a fuel cell system, or the like. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram showing a schematic configuration of a fuel cell system; [Figure 2] 10 is a flowchart illustrating an example of an opening degree control process. [Figure 3] FIG. 10 is a diagram illustrating an example of a threshold opening degree. DETAILED DESCRIPTION OF THE INVENTION

[0009] A. Implementation: 1 is a diagram showing a schematic configuration of a fuel cell system 100 according to this embodiment. The fuel cell system 100 includes a fuel cell 10, a fuel gas supply unit 20, an oxidant gas supply unit 30, and a control unit 40. The fuel cell system 100 according to this embodiment is mounted on, for example, a fuel cell vehicle.

[0010] The fuel cell 10 is a polymer electrolyte fuel cell that generates electricity by receiving a supply of a fuel gas (e.g., hydrogen gas) and an oxidant gas (e.g., air) as reactant gases. The fuel cell 10 is configured by stacking a plurality of unit cells. The fuel cell 10 has an inlet 11 through which the oxidant gas flows in and an outlet 12 through which the oxidant gas flows out.

[0011] The fuel gas supply unit 20 supplies fuel gas to the fuel cell 10. In this embodiment, the fuel gas supply unit 20 supplies hydrogen gas to the fuel cell 10 from a fuel gas tank (not shown).

[0012] The oxidizing gas supply unit 30 supplies an oxidizing gas to the fuel cell 10. In this embodiment, the oxidizing gas supply unit 30 supplies air taken in from the outside to the fuel cell 10. The oxidizing gas supply unit 30 has a gas supply pipe 31, an air flow meter 32, a compressor 33, a pressure sensor 34, a sealing valve 35, a gas exhaust pipe 36, and a pressure regulating valve 37.

[0013] The gas supply pipe 31 is connected to the supply port 11. An air flow meter 32, a compressor 33, a pressure sensor 34, and a sealing valve 35 are provided in this order from upstream to downstream in the gas supply pipe 31.

[0014] The air flow meter 32 measures the flow rate of air taken in from outside through the gas supply pipe 31. The compressor 33 compresses the air taken in from outside in response to a control signal from the control unit 40 and supplies it to the fuel cell 10. The pressure sensor 34 measures the gas pressure of the oxidant gas inside the fuel cell 10. The pressure sensor 34 transmits the measured gas pressure to the control unit 40. In response to a control signal from the control unit 40, the sealing valve 35 seals the supply port 11 while the fuel cell system 100 is stopped. This prevents air from entering the fuel cell 10 and causing a decrease in performance due to carbon oxidation of the catalyst in the fuel cell 10.

[0015] The gas exhaust pipe 36 is connected to the exhaust port 12. A pressure adjusting valve 37 is provided in the gas exhaust pipe 36.

[0016] The pressure regulating valve 37 adjusts the gas pressure by adjusting its opening in response to a control signal from the control unit 40. Furthermore, the pressure regulating valve 37 seals the outlet 12 in response to a control signal from the control unit 40 while the fuel cell system 100 is stopped. This prevents air from entering the fuel cell 10 and causing a decrease in performance due to carbon oxidation of the catalyst in the fuel cell 10. In this embodiment, the pressure regulating valve 37 is a butterfly valve.

[0017] The control unit 40 is configured as a computer including a CPU, memory, and an interface circuit to which each component in the fuel cell system 100 is connected. The control unit 40 outputs a signal for controlling the aperture of the pressure regulating valve 37 so that the gas pressure becomes a target gas pressure. The control unit 40 controls the aperture of the pressure regulating valve 37 in accordance with the gas pressure by executing a control program stored in the memory. However, some or all of this function may be realized by a hardware circuit.

[0018] The control unit 40 controls the aperture of the pressure regulating valve 37 to a tentative target aperture determined in accordance with the target gas pressure. The control unit 40 then controls the aperture of the pressure regulating valve 37 to the target aperture determined in accordance with the gas pressure so that the gas pressure becomes the target gas pressure. For example, when the gas pressure is lower than the target gas pressure, the control unit 40 reduces the aperture of the pressure regulating valve 37 below the tentative target aperture. On the other hand, when the gas pressure is higher than the target gas pressure, the control unit 40 increases the aperture of the pressure regulating valve 37 above the tentative target aperture. After controlling the aperture of the pressure regulating valve 37 to the tentative target aperture, if the gas pressure becomes the target gas pressure, the target aperture remains the tentative target aperture. That is, the control unit 40 maintains the aperture of the pressure regulating valve 37 at the tentative target aperture.

[0019] Furthermore, when an abnormality occurs in the sealing member of the pressure regulating valve 37, the control unit 40 controls the opening of the pressure regulating valve 37 to a corrected opening. The corrected opening is the opening when an abnormality occurs in the sealing member of the pressure regulating valve 37. The corrected opening is an opening determined according to the target gas pressure and is larger than the target opening.

[0020] 2 is a flowchart showing an example of the opening degree control process. The opening degree control process is repeatedly performed while the fuel cell system 100 is in operation and the fuel cell 10 is generating power.

[0021] In step S100, the control unit 40 determines whether or not there is an abnormality in the sealing member of the pressure regulating valve 37. In this embodiment, the control unit 40 determines that there is an abnormality in the sealing member of the pressure regulating valve 37 when the opening degree of the pressure regulating valve 37 is equal to or less than a predetermined threshold opening degree. The threshold opening degree is a value determined according to the target gas pressure. The threshold opening degree can be determined in advance experimentally or empirically.

[0022] FIG. 3 is a diagram showing an example of the threshold opening. In the graph shown in FIG. 3, the horizontal axis represents the target gas pressure value. The vertical axis represents the actual opening of the pressure regulating valve 37. The opening when the sealing member of the pressure regulating valve 37 is normal is indicated by an open circle. The opening when there is an abnormality in the sealing member is indicated by a black circle. Regression line Gr1 is a regression curve of the opening when the sealing member is normal. Regression line Gr2 is a regression curve of the opening when there is an abnormality in the sealing member. Regression line Gr3 is a regression curve obtained by shifting regression line Gr1 downward in parallel by a predetermined threshold, and represents the threshold opening.

[0023] In this embodiment, the control unit 40 controls each component of the fuel cell system 100 so that the supply amount and gas pressure of the oxidant gas supplied to the fuel cell 10 increase as the required output current of the fuel cell 10 increases. Therefore, as the target gas pressure increases, the flow rate of the oxidant gas also increases, so the control unit 40 increases the valve opening as the target gas pressure increases. If there is an abnormality in the sealing member of the pressure regulating valve 37, more specifically, if the sealing member is peeled off, pressure loss occurs due to the sealing member, resulting in a decrease in gas pressure. Therefore, the control unit 40 decreases the opening of the pressure regulating valve 37 to increase the gas pressure to the target gas pressure. Therefore, the opening of the pressure regulating valve 37 when there is an abnormality in the sealing member is smaller than the opening of the pressure regulating valve 37 when the sealing member is normal.

[0024] If there is an abnormality in the sealing member, more specifically, if the opening degree of the pressure regulating valve 37 is equal to or less than the threshold opening degree, the control unit 40 proceeds to the process of step S110 (shown in FIG. 2). On the other hand, if there is no abnormality in the sealing member, more specifically, if the opening degree of the pressure regulating valve 37 is greater than the threshold opening degree, the control unit 40 proceeds to the process of step S125, does not change the opening degree of the pressure regulating valve 37, and ends the opening degree control process.

[0025] In step S110, the control unit 40 notifies the user via a notification device (not shown) that an abnormality has occurred in the sealing member. Note that the process of step S110 may be omitted.

[0026] In step S120, the control unit 40 sets the opening of the pressure regulating valve 37 to a corrected opening that is greater than the target opening.

[0027] According to the fuel cell system 100 of this embodiment described above, the control unit 40 increases the opening of the pressure regulating valve 37 when an abnormality occurs in the sealing member of the pressure regulating valve 37, thereby alleviating stress caused by contact between the pressure regulating valve 37 and the sealing member. As a result, the fuel cell system 100 can continue to operate while preventing the abnormality in the sealing member from becoming more severe.

[0028] B. Other Embodiments: (B1) In the above-described embodiment, the pressure sensor 34 is provided in the gas supply pipe 31 between the compressor 33 and the sealing valve 35. However, the present invention is not limited to this, and the pressure sensor 34 may be provided at any location upstream of the pressure adjustment valve 37.

[0029] (B2) In the above-described embodiment, the pressure regulating valve 37 is a butterfly valve. However, this is not limiting and any valve can be used as the pressure regulating valve 37. The pressure regulating valve 37 may be, for example, a ball valve.

[0030] (B3) In the above-described embodiment, the control unit 40 determines whether there is an abnormality in the sealing member based on whether the opening degree of the pressure regulating valve 37 is equal to or less than the threshold opening degree. This is not limiting, and the control unit 40 may determine whether there is an abnormality in the sealing member based on, for example, whether the opening degree of the pressure regulating valve 37 repeatedly increases and decreases a predetermined number of times or more within a predetermined period. Furthermore, the control unit 40 may determine whether there is an abnormality in the sealing member based on whether it has received a signal indicating an abnormality in the sealing member from a detection unit that detects an abnormality in the sealing member.

[0031] The present disclosure is not limited to the above-described embodiments and can be realized in various configurations without departing from the spirit thereof. For example, the technical features in the embodiments corresponding to the technical features in each aspect described in the Summary of the Invention section can be appropriately replaced or combined to solve the above-described problems or achieve some or all of the above-described effects. Furthermore, if a technical feature is not described as essential in this specification, it can be appropriately deleted. [Explanation of symbols]

[0032] 10... fuel cell, 11... supply port, 12... exhaust port, 20... fuel gas supply unit, 30... oxidant gas supply unit, 31... gas supply pipe, 32... air flow meter, 33... compressor, 34... pressure sensor, 35... valve, 36... gas exhaust pipe, 37... pressure regulating valve, 40... control unit, 100... fuel cell system

Claims

[Claim 1] 1. A fuel cell system, comprising: a fuel cell having a supply port through which an oxidant gas flows and a discharge port through which the oxidant gas flows; a gas supply pipe connected to the supply port; a gas exhaust pipe connected to the exhaust port; a pressure sensor that measures the gas pressure of the oxidant gas in the fuel cell; a pressure regulating valve provided in the gas exhaust pipe to adjust the gas pressure; a control unit that controls the opening degree of the pressure regulating valve, The control unit controls the opening degree of the pressure regulating valve to a target opening determined according to the gas pressure; a corrected opening degree when an abnormality occurs in the sealing member of the pressure regulating valve, the corrected opening degree being larger than the target opening degree.

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