fuel cell system

Abstract

To more appropriately suppress damage to piping, etc. in a gas supply route even when a relief valve on the upstream side of a gas supply route fails or is omitted in a fuel cell system.SOLUTION: A fuel cell system 2 includes a linear solenoid valve 12 that is provided on a supply path 6 that supplies gas to a fuel cell 4, and a relief valve 22 that is located downstream of the linear solenoid valve 12. When the pressure of the gas from the upstream side of the supply path 6 exceeds a predetermined value, the linear solenoid valve is configured to release gas downstream of the linear solenoid valve 12.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The technology disclosed in this specification relates to a fuel cell system. [Background technology]

[0002] The amount of fuel gas supplied when a fuel cell starts generating power is adjusted according to the power generation status of the fuel cell. For example, a system has been disclosed in which a regulator is placed upstream of a fuel gas supply line close to the fuel gas supply source and a relief valve is provided downstream nearby (Patent Document 1). With this system, when gas pressure rises, the relief valve opens to prevent damage to the piping. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-123471 Summary of the Invention [Problem to be solved by the invention]

[0004] Installing a relief valve upstream of the fuel gas supply line can prevent pipe damage under high pressure, but installing a relief valve increases costs, and if the relief valve fails, there is concern that the downstream hydrogen supply line may be damaged.

[0005] The technology disclosed in this specification provides a technology that can more appropriately prevent damage to the piping of the gas supply path in a fuel cell system, even if the relief valve upstream of the gas supply path fails or is omitted. [Means for solving the problem]

[0006] The fuel cell system disclosed in this specification includes a linear solenoid valve and a relief valve disposed downstream of the linear solenoid valve in a supply path that supplies gas to the fuel cell. The linear solenoid valve is configured to release the gas downstream of the linear solenoid valve when the pressure of the gas from the upstream side of the supply path reaches or exceeds a predetermined value.

[0007] According to this fuel cell system, since the linear solenoid valve is provided in the above-described form, the flow rate of gas can be adjusted by energizing the linear solenoid valve. At the same time, when pressure exceeds a predetermined value, the linear solenoid valve opens, suppressing an increase in gas pressure downstream of the supply path. In other words, it functions like a relief valve. Furthermore, by providing a relief valve downstream, gas from an opened linear solenoid valve can be released to the outside of the supply path. According to this fuel cell system, since the linear solenoid valve is provided in the above-described form, an increase in gas pressure can be appropriately suppressed with a simple structure, even if the upstream relief valve fails or is omitted. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 2 is a diagram showing an outline of an example of a gas supply path of a fuel cell system. [Figure 2] 1A and 1B are diagrams illustrating a usage pattern of a linear solenoid valve. DETAILED DESCRIPTION OF THE INVENTION

[0009] The fuel cell system of the present disclosure includes a linear solenoid valve on a gas supply path and a relief valve located downstream of the linear solenoid valve. The linear solenoid valve is configured to release gas from the upstream side of the supply path to the downstream side when the pressure of the gas passing through the supply path reaches a predetermined value or higher. The following embodiments can be adopted.

[0010] In other words, another embodiment of this fuel cell system includes a plunger that blocks or opens the upstream gas inlet, and a spring that biases the plunger to block the gas inlet, the spring having an elastic force that allows it to open the gas inlet by compressing when pressure exceeds the predetermined value. In this way, the linear solenoid valve automatically opens when pressure exceeds the predetermined value.

[0011] In another embodiment of any of the fuel cell systems described above, no relief valve is provided upstream of the linear solenoid valve, which allows for cost reduction.

[0012] In another embodiment of any of the above fuel cell systems, a delivery pipe is further provided upstream of the linear solenoid valve. By providing the delivery pipe, the rate at which the gas pressure increases and the increase in the gas pressure can be suppressed.

[0013] In another embodiment of any of the above fuel cell systems, the gas is fuel gas, and the system further includes an ejector downstream of the linear solenoid valve and upstream of the relief valve that sucks in off-gas from the fuel cell. By including the ejector, gas can be stably supplied to the fuel cell using exhaust gas from the fuel cell, and when the linear solenoid valve is opened, the fuel gas can be effectively caused to flow into the relief valve and released to the outside.

[0014] The following describes an example of a supply path for hydrogen as fuel gas in a fuel cell system disclosed in this specification. FIG. 1 shows an outline of an example of a fuel gas supply path for a fuel cell system, and FIG. 2 shows a usage form of a linear solenoid valve used in the fuel cell system. In this specification, the term "above a predetermined value" can be replaced with the expression "exceeding a predetermined value." In addition, the side of the supply path farther from the fuel cell may be simply referred to as "upstream," and the side closer to the fuel cell may be simply referred to as "downstream."

[0015] The fuel cell system described below includes a fuel cell, which is a stack of multiple fuel cell units stacked in series, a hydrogen supply path for fuel gas, and an air supply path (not shown) for supplying air as an oxidant gas. The hydrogen supply path and the air supply path are each an example of a gas supply path disclosed in this specification. The fuel cell system also includes a cooling system (not shown) including a cooling water pump, a cooling water flow path, and the like. Fuel cell systems are well known in the art and may include various fuel cells, including polymer electrolyte fuel cells (PEFCs). The fuel cell system is not particularly limited in its intended use. For example, it may be a mobile fuel cell system installed in a mobile object such as a vehicle or a ship, or a stationary fuel cell system used in stationary power generation facilities.

[0016] 1, a fuel cell system 2 (hereinafter simply referred to as system 2) includes a fuel cell 4, a hydrogen supply path 6 (hereinafter simply referred to as path 6), and an air supply path (not shown). Also, although not shown, the system 2 includes a control device that controls the flow rate, temperature, pressure, etc. of hydrogen and air in the system 2.

[0017] The line 6 is configured as a piping system equipped with several regulating elements. The line 6 is connected to a hydrogen storage unit located at the most upstream side. The hydrogen storage unit is, for example, a high-pressure hydrogen tank filled with hydrogen at high pressure.

[0018] The system 2 includes a regulator 8 on the path 6 immediately downstream of the hydrogen storage unit. The regulator 8 is a valve that adjusts high-pressure hydrogen to an appropriate pressure in the path 6 and the fuel cell 4. Specifically, the regulator 8 reduces high-pressure hydrogen, for example, of about 70 MPa, to a pressure of, for example, about 1 MPa, which is sufficiently lower than the minimum withstand pressure of the elements downstream of the path 6 and is suitable for flow rate control in the downstream linear solenoid valve 12.

[0019] The system 2 includes a delivery pipe section 10 downstream of the regulator 8. The delivery pipe section 10 is capable of adjusting the pressure of hydrogen in the path 6. The delivery pipe section 10 is generally configured to allow the hydrogen pressure to be lower than at other points in the path 6, and is, for example, made of a large-diameter pipe or has a large-volume cavity.

[0020] The system 2 is equipped with a linear solenoid valve 12 downstream of the delivery piping section 10. The linear solenoid valve 12 allows hydrogen to pass from the upstream side to the downstream side at a predetermined flow rate and a predetermined pressure according to the output required of the fuel cell 4 by a control device. Furthermore, when the pressure of the hydrogen reaching the linear solenoid valve 12 reaches or exceeds a predetermined value, the linear solenoid valve 12 releases hydrogen from the upstream side of the path 6 to its downstream side.

[0021] An example of a linear solenoid valve 12 is shown in Figure 2. As shown in Figure 2, the linear solenoid valve 12 generally includes an electromagnetic hollow coil 14, a plunger 16, and a spring 18 that biases the plunger 16 upstream. The plunger 16 is configured to be movable within the electromagnetic hollow coil 14, and is biased by the spring 18 so as to protrude upstream when not energized, and retracts by the required amount when energized.

[0022] When the electromagnetic hollow coil 14 is not energized, the spring 18 biases the plunger 16 upstream to block the hydrogen inflow path formed by the linear solenoid valve 12. The spring 18 also has an elastic force that contracts when the pressure of hydrogen from the upstream side of the path 6 reaches or exceeds a predetermined value, causing the plunger 16 to move backward and opening the hydrogen inflow path. The spring 18 also has an elastic force that allows it to open the hydrogen flow path when the pressure of hydrogen from the upstream side is sufficiently lower than the lowest pressure (withstand pressure) that could damage elements downstream of the linear solenoid valve 12. For example, the hydrogen pressure (predetermined value) is set to any pressure in the range of 200 to 300 kPa.

[0023] The system 2 includes an ejector 20 downstream of the linear solenoid valve 12. The ejector 20 normally draws in off-gas from the fuel cell 4 in accordance with the amount of hydrogen supplied from the linear solenoid valve 12. The ejector 20 draws in off-gas from the circulation path 7a, which circulates the off-gas from the fuel cell 4, and supplies it to the fuel cell 4 again.

[0024] The system 2 is provided with a relief valve 22 downstream of the ejector 20 and upstream of the fuel cell 4. When the pressure of the hydrogen reaching the relief valve 22 reaches or exceeds a predetermined value, the relief valve 22 automatically opens to release the pressure and discharge the gas in the path 6 to the outside. The pressure at which the relief valve 22 automatically opens is set to be the same as or higher (for example, 300 kPa or higher) than the pressure (for example, 200 to 300 kPa) at which the linear solenoid valve 12 begins to open due to the hydrogen pressure. This allows the pressure in the path 6 to be reduced quickly.

[0025] The system 2 includes a relief valve 22, for example, in a branch path 7b that branches off from the path 6 downstream of the ejector 20 and upstream of the fuel cell 4.

[0026] Next, we will explain what happens when regulator 8 in system 2 breaks down and the hydrogen pressure in path 6 increases. When the pressure in path 6 increases and the gas pressure in linear solenoid valve 12 exceeds a predetermined value, spring 18 contracts, causing plunger 16 to move backward and opening the hydrogen inlet channel of linear solenoid valve 12. This causes the excessive pressure to drop rapidly.

[0027] When the water passage of the linear solenoid valve 12 is opened, hydrogen passes through the ejector 20 and reaches the relief valve 22. The relief valve 22 automatically releases pressure when the pressure reaches or exceeds a predetermined value that is set in advance according to the opening pressure of the linear solenoid valve 12. This ensures that any excessive pressure in the system 2 is released. Furthermore, because only a single relief valve 22 is provided, it is sufficient to connect only a single pipe from the relief valve 22 to release hydrogen, simplifying the release piping system.

[0028] As described above, according to system 2, linear solenoid valve 12 automatically opens at a pressure equal to or greater than a predetermined value set in advance, allowing hydrogen to pass downstream, and further, downstream relief valve 22 opens at a predetermined pressure corresponding to the pressure at which linear solenoid valve 12 opens, thereby releasing hydrogen to the outside of system 2. This prevents damage to path 6 of system 2 and the various elements on path 6.

[0029] According to System 2, the linear solenoid valve 12 functions as a relief valve when the pressure is excessively high. Therefore, in the event of damage to the regulator 8, it is possible to omit the relief valve immediately downstream of the regulator 8, and when such a relief valve is provided, damage to System 2 is suppressed even if the relief valve is damaged.

[0030] System 2 is provided with a linear solenoid valve 12 downstream of delivery piping 10. Delivery piping 10 makes it possible to reduce the inflow of high-pressure gas and reduce the gas pressure in the event of damage to regulator 8. Therefore, releasing hydrogen downstream using linear solenoid valve 12 can also effectively prevent damage to downstream elements.

[0031] The system 2 also includes an ejector 20 located downstream of the linear solenoid valve 12 and upstream of the relief valve 22. The ejector 20 draws off-gas from the fuel cell by controlling the flow rate of hydrogen or the like, without using a pump. Therefore, even if an excessively high pressure occurs in the path 6, the ejector 20 also effectively discharges the off-gas.

[0032] In the above explanation, the elastic force of the spring 18 of the linear solenoid valve 12 is set to open the hydrogen flow path of the linear solenoid valve 12 at a predetermined pressure, but this is not limited to this. For example, the control device may operate the linear solenoid valve 12 to retract the plunger and open the hydrogen flow path based on a signal from a pressure sensor provided in the delivery piping section 10, the linear solenoid valve 12, or in the vicinity thereof.

[0033] Furthermore, in the above description, the path 6 for supplying hydrogen has been described, but the same can be applied to a path for supplying oxidant gas.

[0034] Specific examples of the technology disclosed in this specification have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and variations of the specific examples exemplified above, such as a fuel cell control method. The technical elements described in this specification or in the drawings exhibit technical utility either alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. The technology exemplified in this specification or in the drawings can achieve multiple objectives simultaneously, and achieving one of these objectives itself has technical utility. [Explanation of symbols]

[0035] 2 fuel cell system, 4 fuel cell stack, 6 hydrogen supply path, 7a circulation path, 7b branch path, 8 regulator, 10 delivery piping section, 12 linear solenoid valve, 14 hollow electromagnetic coil, 16 plunger, 18 spring, 20 ejector, 22 relief valve

Claims

1. 1. A fuel cell system, comprising: a linear solenoid valve and a relief valve disposed downstream of the linear solenoid valve on a supply path that supplies gas to the fuel cell; The linear solenoid valve includes a plunger that blocks or opens the gas inlet, and a spring that urges the plunger to block the inlet and has an elastic force that contracts the plunger to open the inlet when the pressure of the gas from the upstream side of the supply path reaches a predetermined value or higher. When the pressure of the gas reaches or exceeds the predetermined value, the linear solenoid valve opens the inlet and opens the relief valve in the supply path.

2. 2. The fuel cell system according to claim 1, wherein no relief valve is provided upstream of said linear solenoid valve.

3. 3. The fuel cell system according to claim 2, further comprising a delivery pipe section upstream of said linear solenoid valve.

4. the gas is a fuel gas; 4. The fuel cell system according to claim 3, further comprising an ejector downstream of said linear solenoid valve and upstream of said relief valve, said ejector sucking off-gas from said fuel cell.

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