JP6919482B2 - Fuel cell system - Google Patents

Description

The present invention relates to a fuel cell system.

In the fuel cell system described in Patent Document 1, a pressure sensor is provided between two valves provided in a pipe for supplying fuel gas used for a fuel cell, and the pressure sensor detects the two valves in a closed state. Based on the inclination of the pressure value, it is determined whether or not there is a leak in the valve, and if there is a leak in the valve, which valve is leaking.

Japanese Unexamined Patent Publication No. 2004-170321

In a large vehicle such as a fuel cell bus, a fuel cell system having a plurality of fuel cell system systems having a fuel cell stack is used. In such a fuel cell system, a communication pipe communicates between the main stop valve and the pressure reducing valve of a plurality of fuel gas tanks. There is an injector downstream of the pressure reducing valve, and when the injector is fully closed to prevent gas from flowing, the pressure downstream of the pressure reducing valve rises and the pressure reducing valve is closed. In this case, since the plurality of fuel cell system systems are communicated by the communication pipe, the pressure between the main stop valve and the pressure reducing valve is the same in all the fuel cell system systems. Therefore, even if an attempt is made to detect a failure of the pressure reducing valve, there is a problem that the failure of the pressure reducing valve cannot be detected unless a pressure sensor is provided downstream of each pressure reducing valve, and the number of pressure sensors increases.

The present invention has been made to solve the above-mentioned problems, and can be realized as the following forms.

(1) According to one embodiment of the present invention, a fuel cell system is provided. This fuel cell system includes a plurality of pressure reducing valves, a plurality of fuel cell stacks provided and connected downstream of the plurality of pressure reducing valves corresponding to each of the plurality of pressure reducing valves, and the pressure reducing valve and the pressure reducing valve. An injector that is provided between the fuel cell stacks corresponding to the above and injects fuel gas into the fuel cell stack corresponding to the pressure reducing valve, and a high pressure piping unit having a communication pipe that communicates upstream of the plurality of pressure reducing valves. During the operation of the pressure sensor provided in the high-pressure piping portion, the gas tank connected to the high-pressure piping portion via the main stop valve, and the fuel cell stack, the injection of the fuel gas from the injector is stopped. After that, the number of failed pressure reducing valves among the plurality of pressure reducing valves is determined from the amount of decrease in pressure per unit time of the pressure sensor when the main stop valve is closed from the valve open state to the valve closed state. A determination unit for determining is provided.

According to this form, the amount of pressure reduction per unit time of the pressure sensor depends on the number of pressure reducing valves that are failing (in this case, leak failure), so that the pressure sensor is reduced in pressure per unit time. From the quantity, the number of failed pressure reducing valves among a plurality of pressure reducing valves can be determined.

The present invention can be realized in various forms, for example, in addition to a fuel cell system, a vehicle equipped with a fuel cell, a method for inspecting a pressure reducing valve, and the like.

It is explanatory drawing which shows typically the structure of the vehicle which carries the fuel cell system. It is a flowchart which inspects the number of failures of a pressure reducing valve. It is a graph which shows the transition of the pressure upstream of a pressure reducing valve.

-Embodiment:
FIG. 1 is an explanatory diagram schematically showing a configuration of a vehicle 10 equipped with a fuel cell system 25. The fuel cell system 25 includes a first fuel cell system system 20 that can operate independently, a second fuel cell system system 21, a communication pipe 224, a pressure sensor 320, and a control unit 300.

The first fuel cell system system 20 includes a gas tank 200, a main stop valve 210, a high-pressure pipe 220, a pressure reducing valve 230, a medium-pressure pipe 240, an injector 250, a low-pressure pipe 260, and a fuel cell stack 270. , Equipped with. The gas tank 200 stores fuel gas. In this embodiment, hydrogen is used as the fuel gas. The main check valve 210 is a valve that turns on / off the supply of fuel gas from the gas tank 200. The high-pressure pipe 220 connects the downstream of the main check valve 210 and the upstream of the pressure reducing valve 230. The pressure reducing valve 230 reduces the pressure of the high-pressure fuel gas supplied from the gas tank 200 to a predetermined pressure (medium pressure) and supplies the pressure downstream. The medium pressure pipe 240 connects the downstream of the pressure reducing valve 230 and the upstream of the injector 250. The injector 250 adjusts the pressure and amount of the fuel gas and injects the fuel gas into the low pressure pipe 260. In the form shown in FIG. 1, the number of injectors 250 is three, but any number of injectors may be used as long as they are one or more. The low-pressure pipe 260 connects the downstream of the injector 250 and the fuel cell stack 270, and supplies the injected fuel gas to the fuel cell stack 270.

Since the configuration of the second fuel cell system system 21 is the same as the configuration of the first fuel cell system system 20, the description thereof will be omitted. In FIG. 1, each configuration of the second fuel cell system system 21 is assigned a code number obtained by adding 1 to the code number of the corresponding configuration of the first fuel cell system system 20.

The communication pipe 224 communicates the high-pressure pipe 220 of the first fuel cell system system 20 and the high-pressure pipe 221 of the second fuel cell system 21. Therefore, the fuel gas in the gas tank 200 can be used in the fuel cell stack 271, and the fuel gas in the gas tank 201 can be used in the fuel cell stack 270. The pressure of the communication pipe 224 is the same as the pressure of the high pressure pipe 220 and 221. Therefore, in the embodiment, the high-pressure pipe 220 and 221 and the communication pipe 224 are collectively referred to as a "high-pressure pipe portion 225". A pressure sensor 320 is provided in the communication pipe 224. However, the pressure sensor 320 may be provided in the high pressure pipe 220 or the high pressure pipe 221. That is, the pressure sensor 320 may be provided somewhere in the high-pressure piping portion 225.

The control unit 300 controls the entire vehicle 10, and controls the operations of the main check valves 210 and 211 and the injectors 250 and 251 in response to the request of the driver of the vehicle 10. The control unit 300 includes a determination unit 310. The determination unit 310 determines the presence or absence of a leak failure of the pressure reducing valves 230 and 231 using the amount of decrease in pressure measured by the pressure sensor 320 per unit time, and if there is a leak failure, further leak failure. Determine the number of pressure reducing valves that have reached. Further, the determination unit 310 grasps the number of fuel cell stacks 270 and 271 capable of generating electricity according to the number of leak failures of the pressure reducing valves 230 and 231, and determines whether or not the vehicle 10 can travel as it is. For example, the determination unit 310 determines that the vehicle 10 can travel as it is when the pressure reducing valves 230 and 231 have a leak failure but only one of them has a leak failure. In this case, the determination unit 310 may issue a warning, store that fact in the memory of the determination unit 310, and allow the vehicle 10 to travel as it is. This is because the leakage of the pressure reducing valves 230 and 231 does not mean that the fuel gas leaks to the outside of the fuel cell system 25. Further, when all the pressure reducing valves 230 and 231 have leak failures, the determination unit 310 determines that the vehicle 10 cannot run as it is, issues a warning, and runs on a secondary battery (not shown). You may switch to.

FIG. 2 is a flowchart for inspecting the number of failures of the pressure reducing valves 230 and 231. This inspection flow is performed during the operation of the fuel cell system 25. In step S100, the determination unit 310 determines whether or not the injectors 250 and 251 can be stopped. For example, when the amount of power generation required for the fuel cell system 25 is equal to or less than a predetermined amount of electric power, the injectors 250 and 251 can be stopped. During the operation of the fuel cell system 25, the pressure downstream of the pressure reducing valves 230 and 231 is lower than the seal pressure Ps of the pressure reducing valves 230 and 231, and the medium pressure pipe 240 is passed through the pressure reducing valves 230 and 231. , 241 and injectors 250 and 251 are supplied with fuel gas. Generally, when the pressure downstream of the pressure reducing valves 230 and 231 rises to a certain pressure, the pressure reducing valves 230 and 231 close. This "certain pressure" is called "seal pressure". Therefore, when the pressure downstream of the pressure reducing valves 230 and 231 is less than the seal pressure Ps, the pressure reducing valves 230 and 231 are in the valve open state and allow fuel gas to pass therethrough. On the other hand, when the pressure downstream of the pressure reducing valves 230 and 231 is equal to or higher than the seal pressure Ps, the pressure reducing valves 230 and 231 are in a closed state and do not allow fuel gas to pass through.

In step S110, the determination unit 310 causes the control unit 300 to stop driving the injectors 250 and 251. As a result, the fuel gas does not flow downstream from the medium pressure pipe 240 via the injectors 250 and 251. On the other hand, since the fuel gas is supplied from the gas tanks 200 and 201 via the pressure reducing valves 230 and 231, the pressure of the medium pressure pipes 240 and 241 rises. When the pressure downstream of the medium pressure pipes 240 and 241 reaches the seal pressure Ps of the pressure reducing valves 230 and 231, the pressure reducing valves 230 and 231 do not allow the fuel gas to pass unless there is a leak failure such as a foreign substance being caught. The pressure of the fuel gas upstream of the pressure reducing valves 230 and 231, that is, the pressure of the fuel gas in the high pressure piping section 225 is originally high because the main shutoff valves 210 and 211 are open, but the injectors 250 and 251 are closed or the pressure reducing valves 230, When the 231 does not allow the fuel gas to pass through, the pressure rises to the pressure of the gas tanks 200 and 201.

In step S120, the determination unit 310 acquires the pressure P1 upstream of the pressure reducing valves 230 and 231 from the pressure sensor 320. In step S130, the determination unit 310 determines whether or not the value obtained by subtracting the seal pressure Ps from the pressure P1 exceeds ΔP. In this embodiment, since the pressure sensor is not provided downstream of the pressure reducing valves 230 and 231, it cannot be directly determined whether or not the pressure downstream of the pressure reducing valves 230 and 231 exceeds the sealing pressure Ps. ΔP is a pressure for determining whether or not the pressure downstream of the pressure reducing valves 230 and 231 exceeds the sealing pressure Ps from the pressure upstream of the pressure reducing valves 230 and 231. That is, if the value obtained by subtracting the seal pressure Ps from the pressure P1 exceeds ΔP, the determination unit 310 causes the fuel gas to flow downstream through the pressure reducing valves 230 and 231 and the pressure downstream of the pressure reducing valves 230 and 231. Can be determined to exceed the sealing pressure Ps. On the other hand, if it does not exceed ΔP, it can be determined that the fuel gas flows downstream through the pressure reducing valves 230 and 231 and the pressure downstream of the pressure reducing valves 230 and 231 does not exceed the sealing pressure Ps. If the pressure downstream of the pressure reducing valves 230 and 231 does not exceed the sealing pressure Ps, the pressure reducing valves 230 and 231 will not close. In addition, ΔP is obtained experimentally, for example.

If the value obtained by subtracting the seal pressure Ps from the pressure P1 in step S130 exceeds ΔP, the process proceeds to step S140, and if it does not exceed ΔP, the process ends. When the value obtained by subtracting the sealing pressure Ps from the pressure P1 exceeds ΔP, it can be determined that the pressure downstream of the pressure reducing valves 230 and 231 exceeds the sealing pressure Ps, and when the pressure reducing valves 230 and 231 are closed. I can judge. When the value obtained by subtracting the sealing pressure Ps from the pressure P1 is ΔP or less, the pressure downstream of the pressure reducing valves 230 and 231 does not exceed the sealing pressure Ps and the pressure reducing valves 230 and 231 do not close, so that foreign matter is caught. Even without it, it can be determined that the pressure reducing valves 230 and 231 may not be completely closed. Therefore, the process ends.

In step S140, the determination unit 310 instructs the control unit 300 to close the main check valves 210 and 211, and the control unit 300 closes the main check valves 210 and 211.

In step S150, the determination unit 310 determines whether a predetermined time Δt has elapsed from the closing of the main check valves 210 and 211, and the predetermined time Δt has been set since the closing of the main check valves 210 and 211. If it has passed, the process proceeds to step S160. The length of Δt is preset, for example, by examining the change in pressure when the pressure reducing valves 230 and 231 have a leak failure and when there is no leak failure, for example, by an experiment or the like. In step S160, the determination unit 310 acquires the pressure P2 upstream of the pressure reducing valves 230 and 231 after the main stop valves 210 and 211 are closed from the pressure sensor 320. In step S170, the determination unit 310 calculates the amount of pressure decrease per unit time from the pressures P1 and P2 and the elapsed time Δt. In step S180, the determination unit 310 determines how many of the pressure reducing valves 230 and 231 have leaked failures based on the amount of pressure decrease per unit time, and the number of failures.

Since the fuel gas is not supplied from the gas tanks 200 and 201 after the main check valves 210 and 211 are closed, the pressure upstream of the pressure reducing valves 230 and 231 is either maintained as it is or decreased. be. Further, when the main check valves 210 and 211 are closed, the pressure downstream of the pressure reducing valves 230 and 231 exceeds the sealing pressure Ps. Therefore, if there is no leak failure such as foreign matter getting caught in the pressure reducing valves 230 and 231, the pressure reducing valves 230 and 231 do not allow fuel gas to pass through. The upstream pressure is maintained as it is. On the other hand, if the pressure reducing valves 230 and 231 have leak failures such as foreign matter being caught, the pressure upstream of the pressure reducing valves 230 and 231 decreases according to the number of leak failures. Therefore, it is possible to determine how many of the pressure reducing valves 230 and 231 have leak failures and the number of leak failures from the amount of pressure decrease per unit time upstream of the pressure reducing valves 230 and 231.

FIG. 3 is a graph showing the transition of the pressure upstream of the pressure reducing valves 230 and 231. The time t1 is the time when the drives of the injectors 250 and 251 in step S110 of FIG. 2 are stopped. Although not shown, the fuel gas flows downstream through the pressure reducing valves 230 and 231, so that the pressure downstream of the pressure reducing valves 230 and 231 increases. When the pressure downstream of the pressure reducing valves 230 and 231 reaches the seal pressure Ps, the pressure reducing valves 230 and 231 are closed, so that the fuel gas does not flow downstream.

The time t2 is the time when the pressure P1 upstream of the pressure reducing valves 230 and 231 in step S120 of FIG. 2 is acquired and the main check valves 210 and 211 of S140 are closed. When the main check valves 210 and 211 are closed, fuel gas is no longer supplied upstream of the pressure reducing valves 230 and 231. After that, if there is no leak failure such as foreign matter getting caught in the pressure reducing valves 230 and 231, the pressure upstream of the pressure reducing valves 230 and 231 after the main stop valves 210 and 211 are closed is maintained as it is. On the other hand, if there is a leak failure such as foreign matter getting caught in the pressure reducing valves 230 and 231, fuel gas flows downstream of the pressure reducing valves 230 and 231 according to the number of the leak failures. The pressure upstream of the pressure reducing valves 230 and 231 of the pressure reducing valve 230 and 231 is reduced.

The time t3 is the time when the pressure P2 upstream of the pressure reducing valve 230 and 231 in step S160 of FIG. 2 was acquired. As can be seen from the graph, when there is no leak failure in the pressure reducing valves 230 and 231, the pressure P2 upstream of the pressure reducing valves 230 and 231 after the main stop valves 210 and 211 are closed is the pressure P2 of the main stop valves 210 and 211. The pressure is almost the same as the pressure P1 upstream of the pressure reducing valves 230 and 231 before closing the valve. On the other hand, when the pressure reducing valves 230 and 231 have leak failures, the pressure P2 upstream of the pressure reducing valves 230 and 231 decreases according to the number of leak failures. That is, the pressure is further reduced when the number of leak failures is two than when it is one. Therefore, the determination unit 310 can determine whether or not there is a leak failure in the pressure reducing valves 230 and 231 and the number of leak failures based on the amount of decrease in the pressure upstream of the pressure reducing valves 230 and 231 per unit time.

As described above, according to the above embodiment, the presence or absence of a leak failure of the pressure reducing valves 230 and 231 and the presence or absence of a leak failure of the pressure reducing valves 230 and 231 are determined from the amount of decrease in the pressure upstream of the pressure reducing valves 230 and 231 after closing the main stop valves 210 and 211. The number of leak failures can be determined. Then, the determination unit 310 can grasp the number of fuel cell stacks 270 and 271 capable of generating electricity according to the number of leak failures of the pressure reducing valves 230 and 231 and determine whether or not the vehicle 10 can travel as it is. .. If the amount of decrease in the pressure upstream of the pressure reducing valves 230 and 231 per unit time, that is, the rate of decrease in pressure is known, Δt does not necessarily have to be constant.

In the above embodiment, since the fuel gas is filled from the gas tank of the gas station into the gas tank, the gas tank contains almost no impurities that cause a large leak in the pressure reducing valves 230 and 231. A filter for filtering impurities that cause a large leak may be provided on the upstream side of the pressure reducing valves 230 and 231. In this way, it is possible to suppress a failure in which large impurities are caught in the pressure reducing valves 230 and 231 and cause a large leak.

In the above embodiment, if a sufficient time can be secured as Δt, the determination unit 310 may determine as follows.

The volume of the high-pressure piping section 225 is Va, the volume of the medium-pressure piping 240 and 241 is Vb, and the pressure of the high-pressure piping section 225 when the pressure downstream of the pressure reducing valves 230 and 231 reaches Ps is P1, the pressure reducing valves 230 and 231. Assuming that the number of moles of fuel gas in the high-pressure piping section 225 when the pressure downstream of the pipe reaches Ps is na, the number of moles of fuel gas in the medium-pressure pipes 240 and 240 is nb, and the temperature is T, the following states are obtained. The equation holds.
P1Va = naRT ⇒ na = P1Va / RT ・ ・ ・ (1)
PsVb = nbRT ⇒ nb = PsVb / RT ... (2)

(A) When there is no failure in the pressure reducing valves 230 and 231, the pressure of the high pressure piping unit 225 does not change at P1 even after Δt elapses. That is,
P2 = P1 ... (3)
Will be.

(B) When one of the pressure reducing valves 230 and 231 has a failure, the following equation of state holds.
P2 (Va + Vb) = (na + nb) RT ... (4)
Therefore,
P2 = (P1Va + PsVb) / (Va + Vb) ... (5)
Will be.

(C) When both the pressure reducing valves 230 and 231 are out of order, the following equation of state holds.
P2 (Va + 2Vb) = (na + 2nb) RT ... (6)
Therefore, P2 = (P1Va + 2PsVb) / (Va + 2Vb) ... (7)
Will be.

Va, Vb, and Ps are known. Therefore, the determination unit 310 can determine how many pressure reducing valves are out of order from the measured value of P2, depending on whether or not there is a failure and which of the above equations (5) and (7) is met. If a difference is provided between the volume of the medium pressure pipe 240 and the volume of the medium pressure pipe 241, the determination unit 310 can determine which pressure reducing valve is out of order from the measured value of P2.

-Other embodiments:
In the above embodiment, the time from the time t1 (step S110) to the time t2 (step S140) is not limited, but it is preferable that this time is short. Generally, the pressure inside the gas tanks 200 and 201 is larger than the pressure of the high-pressure pipes 225 and the medium-pressure pipes 240 and 241. Therefore, when the injectors 250 and 251 are stopped, the pressures of the pressure reducing valves 230 and 231 immediately reach the sealing pressure Ps. Here, if the pressure reducing valves 230 and 231 have a leak failure due to the biting of foreign matter, the pressure reducing valves 230 and 231 cannot be completely closed. As a result, even if the pressure downstream of the pressure reducing valves 230 and 231 exceeds the seal pressure Ps, the fuel gas flows downstream through the pressure reducing valves 230 and 231, and the pressure downstream of the pressure reducing valves 230 and 231 also keeps the seal pressure Ps. Rise beyond. If the pressure downstream of the pressure reducing valves 230 and 231 rises too much, the difference between the pressure upstream and the pressure downstream of the pressure reducing valves 230 and 231 when the main check valves 210 and 211 are closed is small, so that the pressure reducing valves 230 and 231 Even if the number of leak failures is large, the amount of decrease in the pressure upstream of the pressure reducing valves 230 and 231 per unit time after closing the main check valves 210 and 211 is small. Therefore, the time from the time t1 (step S110) to the time t2 (step S140) should be short.

In the above embodiment, the determination unit 310 stops driving the injectors 250 and 251 in step S110 when the injectors 250 and 251 can be stopped in step S100. Immediately before stopping the driving of the injectors 250 and 251 in step S110, the determination unit 310 instructs the control unit 300 to inject a large amount of fuel gas from the injectors 250 and 251. A large amount of fuel gas may be injected into the fuel cell stacks 270 and 271 with respect to 251. In this way, a large amount of fuel gas can be present in the low pressure pipes 260, 261 and the fuel cell stacks 270, 271. Therefore, even if there is a request for electric power to the fuel cell system 25 during the subsequent processing of the flow for inspecting the failure of the pressure reducing valves 230 and 231, the fuel cell stacks 270 and 271 use this fuel. It can be used to generate electricity and supply electricity. That is, it is not necessary to interrupt the flow to be inspected for power generation and drive the injectors 250 and 251.

In the above embodiment, two fuel cell system systems, a first fuel cell system system 20 and a second fuel cell system system 21, are provided, but the number of fuel cell system systems is 3 or more. You may.

In the above embodiment, the medium pressure pipes 240 and 241 and the low pressure pipes 260 and 261 are not provided with the pressure sensor, but the pressure sensor may be provided.

The present invention is not limited to the above-described embodiment and other embodiments, and can be realized by various configurations within a range not deviating from the gist thereof. For example, the embodiment corresponding to the technical feature in each embodiment described in the column of the outline of the invention, the technical feature in another embodiment may be used to solve a part or all of the above-mentioned problems, or In order to achieve a part or all of the above-mentioned effects, it is possible to replace or combine them as appropriate. Further, if the technical feature is not described as essential in the present specification, it can be deleted as appropriate.

10 ... Vehicle 20 ... First fuel cell system system 21 ... Second fuel cell system system 25 ... Fuel cell system 200, 201 ... Gas tank 210, 211 ... Main stop valve 220, 221 ... High pressure pipe 224 ... Communication pipe 225 ... High-pressure piping unit 230, 231 ... Pressure reducing valve 240, 241 ... Medium-pressure piping 250, 251 ... Injectors 260, 261 ... Low-pressure piping 270, 271 ... Fuel cell stack 300 ... Control unit 310 ... Judgment unit 320 ... Pressure sensor

Claims (1)

It ’s a fuel cell system,
With multiple pressure reducing valves,
A plurality of fuel cell stacks provided and connected downstream of the plurality of pressure reducing valves corresponding to each of the plurality of pressure reducing valves,
An injector provided between the pressure reducing valve and the fuel cell stack corresponding to the pressure reducing valve and injecting fuel gas into the fuel cell stack corresponding to the pressure reducing valve.
A high-pressure piping section having a communication pipe that communicates upstream of the plurality of pressure reducing valves,
The pressure sensor provided in the high-pressure piping section and
A gas tank connected to the high-pressure piping section via a main check valve,
During the operation of the fuel cell stack, the pressure per unit time of the pressure sensor when the injection of the fuel gas from the injector is stopped and then the main check valve is closed from the valve open state to the valve closed state. A determination unit that determines the number of failed pressure reducing valves among the plurality of pressure reducing valves from the amount of decrease in
A fuel cell system.

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