JP2005158282A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system capable of efficiently heating a control valve and starting early by a simple constitution. <P>SOLUTION: When the fuel cell system is stopped operation, a control part closes a first pressure control valve 5 and a second pressure control valve 6 of a hydrogen flow-passage 2, opens a backpressure control valve 7, a shut-off valve 9, and a shut-off valve 11 of a bypath route 10, and opens the interior of the fuel cell body 1 to the air. Furthermore, the back-pressure control valve 16 of an air flow-passage 3 is closed, the bypath route 17 is selected by a three-way valve 18, and a gas flow into the main body side flow passage 3a is made to a shut-off state. When the control part detects freezing of the control valve in starting operation of the system, it makes the air flow into bypath routes 10 and 17 by actuating a hydrogen pump 8 and an air pump 15 prior to starting of the fuel cell system, and heats the control valve by this. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a fuel cell system, and more particularly to a fuel cell system that generates power by supplying hydrogen and air to a fuel cell main body from a hydrogen channel and an air channel, respectively.

  In recent years, a fuel cell system that generates electricity by an electrochemical reaction between hydrogen and oxygen has attracted attention as an energy source. In such a fuel cell system, when the temperature of the outside air falls below, for example, below freezing point, moisture in the gas is discharged from a control valve such as a discharge valve or a check valve provided on the flow path of the gas discharged from the fuel cell body. Condensation and freezing or residual moisture may freeze, and it may become impossible to control the opening and closing of these control valves. In that case, the system cannot be started until the freezing of the control valve is eliminated, and a considerable time is required until the system is started.

  On the other hand, for example, in the fuel cell system disclosed in Patent Document 1, control valves such as a discharge valve and a check valve are arranged in the warm air box, and the shunt flow path connects the downstream of the air compressor and the warm air box. In addition, a shunt valve that circulates and shuts off this shunt flow path is provided, and when the control valve is frozen, the shunt valve is opened and the shunt flow path is opened to supply hot air that is adiabatically compressed by the air compressor into the warm air box Thus, the control valve is heated and defrosted.

JP 2002-313389 A

However, in the fuel cell system of Patent Document 1, not only the warm air box that houses the control valve, but also a shunt flow path that connects the downstream of the air compressor and the warm air box, a shunt valve that circulates and shuts off this shunt flow path, and the like. Since it is necessary to provide, the whole fuel cell system will be a complicated structure.
Further, each control valve may be heated by attaching a heating device such as a heater. However, since it is necessary to provide a dedicated heating device for each control valve, the fuel cell system as a whole also has a complicated configuration. End up.
The present invention has been made to solve such a problem, and an object of the present invention is to provide a fuel cell system capable of efficiently starting a control valve with a simple configuration and starting it at an early stage.

A fuel cell system according to the present invention is a fuel cell system that generates power by supplying hydrogen and air to a fuel cell main body through a control valve from a hydrogen channel and an air channel, respectively. At least one of the gas flow paths is a selection means for selecting one of a bypass path for flowing gas bypassing the fuel cell main body and the control valve, and a main body side flow path and bypass path passing through the fuel cell main body. And a gas flow means for flowing gas through the bypass path, and the main body side flow path is selected by the selection means during operation, and the bypass path is selected by the selection means and the gas flow means is operated when the control valve is frozen. And a controller that heats the control valve by flowing gas through the bypass.
In at least one of the gas flow paths, when the gas flow means is operated by the control unit when the control valve is frozen, the control valve is efficiently operated by bypassing the fuel cell main body and the control valve and flowing the gas to the bypass path. Heated and thawed. Therefore, it is not necessary to attach a dedicated heating device such as a heater to each control valve, and the entire system including the control valve can be efficiently warmed up with a simple system configuration.

The bypass passage, the selection means, and the gas flow means are preferably provided in both the hydrogen flow path and the air flow path, respectively. Thereby, both the control valve provided in the hydrogen flow path and the control valve provided in the air flow path can be heated.
At least one of the gas flow paths further includes a circulation pipe for circulating the exhaust gas discharged from the fuel cell main body upstream of the fuel cell main body, and when the control valve is frozen, the circulation pipe, the bypass path, and the selection means More preferably, the gas flow means forms a closed circuit. By circulating the gas in the closed circuit, the entire system including the control valve can be warmed up more efficiently.

As a selection means, a shut-off valve can be disposed in the middle of the bypass path, and a three-way valve can be disposed at a branch point between the main body side flow path and the bypass path.
The control unit preferably controls the operating time of the gas circulation means or the flow rate of the gas circulated by the gas circulation means according to the charge capacity of the battery.
Moreover, it is preferable that a gas distribution | circulation means is a pump for flowing gas into a main body side flow path at the time of a driving | operation. In this way, if a pump is used to flow the gas through the flow path on the main body side during operation and the gas is allowed to flow through the bypass pipe when the control valve is frozen, it is necessary to provide a dedicated pump for flowing the gas through the bypass pipe. And the system configuration becomes simpler.

  According to the present invention, at least one of the hydrogen flow path and the air flow path includes a bypass path for flowing gas bypassing the fuel cell main body and the control valve, and a main body side passing through the fuel cell main body. Selection means for selecting one of the flow path and the bypass path, a gas flow means for flowing gas through the bypass path, a flow path for the main body is selected by the selection means during operation, and a selection means when the control valve is frozen Since the control unit that heats the control valve by flowing the gas through the bypass path by selecting the bypass path and operating the gas flow means is provided, the control valve is efficiently heated with a simple configuration and started early. be able to.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
Embodiment 1 FIG.
FIG. 1 shows a schematic diagram of a fuel cell system according to Embodiment 1 of the present invention. This system has a fuel cell main body (FC stack) 1 that generates electric power by an electrochemical reaction between hydrogen and oxygen in the air, and the electric power generated by the main body 1 can be used as a drive source for a vehicle or the like. . The fuel cell system also includes a hydrogen flow path 2 for supplying hydrogen to the hydrogen electrode of the fuel cell main body 1, and an air flow path 3 for supplying air (oxygen) to the oxygen electrode of the fuel cell main body 1. have.

The hydrogen flow path 2 includes a main body side flow path 2a for supplying hydrogen to the hydrogen electrode through the fuel cell main body 1, a supply flow path 2b connected to the supply side of the main body side flow path 2a, And a discharge channel 2c connected to the discharge side of the side channel 2a. A high pressure hydrogen tank 4 is connected to the supply flow path 2 b, and a first pressure adjustment valve 5 and a second pressure adjustment valve 6 are disposed downstream of the tank 4. On the other hand, a back pressure adjusting valve 7 for adjusting the pressure in the fuel cell main body 1 is arranged in the discharge flow path 2c, and a hydrogen pump 8 composed of a Roots type compressor or the like is arranged downstream thereof. A shutoff valve 9 is arranged downstream of the pump 8. The downstream of the shutoff valve 9 is open to the atmosphere.
Here, a bypass passage 10 is formed between the supply passage 2b and the discharge passage 2c to bypass the fuel cell body 1, the second pressure adjustment valve 6, and the back pressure adjustment valve 7, and this bypass passage is formed. A shut-off valve 11 is arranged in the middle of 10. Further, downstream of the hydrogen pump 8 is a circulation channel 12 for circulating the hydrogen off-gas discharged from the main body side channel 2a of the fuel cell main body 1 to the discharge channel 2c to the supply channel 2b by the hydrogen pump 8. A check valve 13 that prevents the backflow of gas from the supply flow path 2 b to the discharge flow path 2 c is disposed in the middle of the circulation flow path 12.

Similarly, the air flow path 3 is also connected to the main body side flow path 3a for supplying air (oxygen) to the oxygen electrode through the fuel cell main body 1 and the supply side of the main body side flow path 3a. It has a supply flow path 3b and a discharge flow path 3c connected to the discharge side of the main body side flow path 3a. The upstream of the supply flow path 3b and the downstream of the discharge flow path 3c are open to the atmosphere. A humidification module 14 is disposed in the middle of the supply flow path 3b and the discharge flow path 3c. In addition, an air pump 15 made of a roots compressor or the like is disposed upstream of the humidification module 14 in the supply flow path 3b. On the other hand, a back pressure adjusting valve 16 for adjusting the pressure in the fuel cell main body 1 is disposed upstream of the humidifying module 14 in the discharge flow path 3c.
Here, between the supply flow path 3b and the discharge flow path 3c, a bypass path 17 that bypasses the fuel cell body 1, the back pressure adjustment valve 16, and the humidification module 14 is formed. A three-way valve 18 is arranged at a branch point with the flow path 3b.

The fuel cell system has a control unit (not shown). The control unit includes a hydrogen pump 8 in the hydrogen flow path 2, a first pressure adjustment valve 5, a second pressure adjustment valve 6, a back pressure adjustment valve 7, The shutoff valve 9 and the shutoff valve 11 of the bypass passage 10 are electrically connected to the air pump 15, the back pressure adjusting valve 16, and the three-way valve 18 in the air flow path 3, respectively.
During normal operation, the control unit opens the first pressure adjustment valve 5 and the second pressure adjustment valve 6 in the hydrogen flow path 2 and adjusts the opening of the back pressure adjustment valve 7, thereby shutting off the shutoff valve 9 and the bypass path. 10 shut-off valve 11 is closed. Further, the opening degree of the back pressure adjustment valve 16 in the air flow path 3 is adjusted, and the main body side flow path 3a is selected by the three-way valve 18 so that the bypass path 17 is blocked.

  During normal operation, the hydrogen supplied from the high-pressure hydrogen tank 4 to the supply flow path 2b in the hydrogen flow path 2 is adjusted to a predetermined pressure via the first pressure adjustment valve 5 and the second pressure adjustment valve 6, and the main body side flow path. At the same time as air is supplied to 2a, air is supplied to the main body side flow path 3a through the supply flow path 3b by the air pump 15 in the air flow path 3, and the hydrogen and the air thus supplied into the fuel cell main body 1 are in the air. Electric power is generated by electrochemical reaction with oxygen. At this time, in the hydrogen flow path 2, part of the hydrogen off-gas discharged from the fuel cell body 1 to the discharge flow path 2 c is circulated through the circulation flow path 12 to the supply flow path 2 b by the hydrogen pump 8. As a result, unused hydrogen contained in the hydrogen off-gas is circulated and reused in the fuel cell body 1.

Next, when the operation of the fuel cell system is stopped, the control unit closes the first pressure adjustment valve 5 and the second pressure adjustment valve 6 in the hydrogen flow path 2 and opens the back pressure adjustment valve 7 and the shutoff valve 9 to perform fuel. The inside of the battery body 1 is opened to the atmosphere. Further, the back pressure adjustment valve 16 in the air flow path 3 is closed.
In addition, the control unit opens the shutoff valve 11 of the bypass passage 10 in the hydrogen passage 2 to circulate the bypass passage 10, and selects the bypass passage 17 by the three-way valve 18 of the air passage 3. The gas flow to 3a is shut off. Thereafter, the control unit closes the shutoff valve 9 of the hydrogen flow path 2.

Here, the moisture contained in the hydrogen off-gas or air condenses or freezes when the fuel cell system is shut down, for example, when the outside air temperature drops below the freezing point, or the remaining moisture condenses. Thus, at the start of operation, control valves such as the back pressure adjustment valve 7 of the hydrogen flow path 2 and the back pressure adjustment valve 16 of the air flow path 3 may be frozen and cannot be operated. When the control unit detects the freezing of the control valve, it activates the hydrogen pump 8 and the air pump 15 prior to starting the fuel cell system.
At this time, in the hydrogen flow path 2, since the shut-off valve 11 of the bypass path 10 is opened and the shut-off valve 9 is closed, the hydrogen pump 8 causes air to flow through the bypass path 10, thereby bypassing The second pressure regulating valve 6 and the back pressure regulating valve 7 located in the vicinity of the passage 10 are heated. At this time, the shut-off valve 11 of the bypass passage 10 also functions as a back pressure adjusting valve that adjusts the back pressure of the hydrogen pump 8, and the air is adiabatically compressed upstream of the shut off valve 11 to increase the pressure. A heated gas is produced.
Further, in the air flow path 3, since the three-way valve 18 selects the bypass path 17, air is caused to flow through the bypass path 17 by the air pump 15, thereby the humidification module 14 and the back pressure located near the bypass path 17. The regulating valve 16 is heated. At this time, the three-way valve 18 also functions as a back pressure adjusting valve that adjusts the back pressure of the air pump 15. Air is adiabatically compressed on the upstream side of the three-way valve 18 to generate high-pressure heated gas.

  In this way, air flows through the bypass passages 10 and 17 of the hydrogen passage 2 and the air passage 3, and the control valve is efficiently heated and defrosted. Therefore, it is not necessary to attach a dedicated heating device such as a heater to each control valve, and the control valve can be efficiently heated with a simple system configuration. As a result, the entire system is warmed up efficiently, and the system can be started early.

Further, when the control valve is heated, in the hydrogen flow path 2, the second pressure regulating valve 6 is closed, and the upstream side of the shutoff valve 11 of the bypass path 10 and the main body side flow path 2 a are blocked. There is no possibility that the high-pressure air compressed by the hydrogen pump 8 acts on the main body side flow path 2a and damages the inside of the fuel cell main body 1. Further, since the main body side flow path 2a communicates with the downstream side of the shutoff valve 11 of the bypass path 10, the heated air whose pressure has been reduced can flow around the main body side flow path 2a. It is possible to warm the inside of the battery body 1.
Similarly, in the air flow path 3, the bypass path 17 is selected by the three-way valve 18, and the upstream side of the three-way valve 18 in the supply flow path 3 b and the main body side flow path 3 a are blocked. There is no possibility that the high-pressure air compressed by 15 acts on the main body side flow path 3a and damages the inside of the fuel cell main body 1.

In the hydrogen flow path 2, when air is passed through the bypass path 10 by the hydrogen pump 8, a closed circuit is formed from the bypass path 10, the hydrogen pump 8, and the circulation flow path 12. The air that circulates and circulates in the closed circuit is adiabatically compressed by the hydrogen pump 8 to a high temperature. Therefore, even if the first pressure regulating valve 5, the check valve 13, the shutoff valve 9 and the like are frozen, they are heated and thawed by the circulating air. In this way, the entire system including the control valve can be warmed up more efficiently.
In addition, when the system is stopped, the shutoff valve 11 of the bypass passage 10 in the hydrogen passage 2 is opened in advance, and the bypass passage 17 is selected by the three-way valve 18 in the air passage 3, so that these hydrogen passages at the time of starting the system. 2 and the three-way valve 18 of the air flow path 3 are frozen, by driving the hydrogen pump 8 and the air pump 15, the hydrogen flow path 2 and the bypass paths 10 and 17 of the air flow path 3 are respectively connected. Air can be flowed to heat the control valve.

  In the first embodiment described above, instead of opening the back pressure adjusting valve 7 and the shutoff valve 9 and releasing to the atmosphere when the system is stopped, the control unit controls the second pressure adjusting valve in the hydrogen flow path 2 prior to stopping the system. 6 and the back pressure regulating valve 7 are closed, the first pressure regulating valve 5, the shutoff valve 9 and the shutoff valve 11 of the bypass passage 10 are opened, and the first pressure regulating valve 5 and the bypass passage 10 are opened from the high pressure hydrogen tank 4. The dry pump that has not passed through the fuel cell main body 1 is allowed to flow through the hydrogen pump 8 through the shutoff valve 11 to scavenge, and then the first pressure regulating valve 5 and the shutoff valve 9 are closed to stop the system. it can. In this way, when the system is stopped, the first pressure regulating valve 5, the second pressure regulating valve 6, the back pressure regulating valve 7 and the shut-off valve 9 are closed, and the shut-off valve 11 of the bypass passage 10 is opened. Therefore, dry hydrogen remains in the closed circuit formed by the bypass passage 10, the hydrogen pump 8, and the circulation passage 12. Therefore, when the hydrogen pump 8 is operated when the control valve is frozen, the dried hydrogen is circulated in the closed circuit. Even if it does in this way, a control valve is heated by flowing hydrogen into bypass way 10, and the same effect as Embodiment 1 can be acquired.

  In addition, as described above, after the system is shut down, the dry hydrogen is flowed from the high-pressure hydrogen tank 4 to the hydrogen pump 8 through the first pressure regulating valve 5 and the shutoff valve 11 of the bypass passage 10, and then the bypass is performed. When the system is stopped by closing the first pressure regulating valve 5 and the shut off valve 9 while the shutoff valve 11 of the passage 10 is open, the first pressure regulating valve 5 is opened and the hydrogen pump 8 is operated when the control valve is frozen. Even if the control valve is heated by flowing hydrogen from the high-pressure hydrogen tank 4 to the bypass passage 10, the same effect as in the first embodiment can be obtained.

In the first embodiment described above, a restriction is provided in the bypass path 10 of the hydrogen flow path 2 or the pipe diameter of the bypass path 10 is formed smaller than the pipe diameter of the hydrogen flow path 2 or both. If this is done, a further load is applied to the hydrogen pump 8, so that a higher temperature gas can flow through the bypass passage 10, thereby improving the warming efficiency. Similarly, in the air flow path 3, a restriction is provided in the bypass path 17, or the pipe diameter of the bypass path 17 is formed smaller than the pipe diameter of the air flow path 3. The warming efficiency can be improved.
Further, in the hydrogen flow path 2, a three-way valve may be arranged at the branch point between the bypass path 10 and the supply flow path 2 b in the same manner as the air flow path 3 instead of providing the shut-off valve 11 in the bypass path 10. At this time, if the opening when the three-way valve selects the main body side flow path 2a and the opening of the second pressure regulating valve 6 are set equal, it is not necessary to provide the second pressure regulating valve 6.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to FIG. The fuel cell system according to Embodiment 2 is the same as the fuel cell system according to Embodiment 1 shown in FIG. That is, in the air flow path 3, one end of the circulation flow path 21 is connected upstream of the pump 15, and the other end is connected downstream of a branch point with the bypass path 17 of the discharge flow path 3c. Note that the configuration and operation of the hydrogen flow path 2 are the same as those in the first embodiment, and are therefore omitted.

Even in this way in the air flow path 3, if the air pump 15 is activated by the control unit when the control valve is frozen, the air is bypassed into the bypass path 17, bypassing the fuel cell body 1, the back pressure adjustment valve 16, and the humidification module 14. And the control valve is heated, and the same effect as in the first embodiment is obtained.
In addition, since the fuel cell system of the second embodiment has the circulation flow path 21, a closed circuit is formed from the bypass path 17, the air pump 15, and the circulation flow path 21, and air is passed through the closed circuit. The air circulating in the closed circuit is adiabatically compressed by the air pump 15 and becomes high temperature. Therefore, the entire system including the control valve can be warmed up more efficiently.

  In the second embodiment described above, the throttle part is provided in the circulation channel 21 of the air channel 3, or the pipe diameter of the circulation channel 21 is formed smaller than the pipe diameter of the air channel 3, or both As a result, the load is further applied to the air pump 15, so that the air can be made to flow at a higher temperature, and the warming-up efficiency can be further improved. When a load is applied to the air pump 15 as described above, it is necessary to provide a shutoff valve that is closed at the time of warm-up, that is, when the control valve is heated, downstream of the branch point of the discharge flow path 3c with the circulation flow path 21.

  In the first and second embodiments described above, the control unit includes an outside air temperature sensor that detects the outside air temperature. When the outside air temperature measured by the outside air temperature sensor becomes a predetermined temperature or lower, the control valve Freezing can be detected. In addition, a state sensor that detects the open / close state of the control valve is provided, and the control unit controls the control valve when the open / close state of the control valve detected by the state sensor becomes an unexpected state when performing the open / close control of the control valve. In this case, it can be detected whether or not each control valve is frozen. Here, in the first and second embodiments described above, the control unit operates both the hydrogen pump 8 and the air pump 15 when the control valve is frozen, but when the frozen state for each control valve can be detected in this way, Of the hydrogen flow path 2 and the air flow path 3, only the pump in the gas flow path having the frozen control valve can be operated. In this way, the power consumed for the warming-up operation performed prior to system startup is reduced, and an energy-saving fuel cell system can be realized.

In the case where the fuel cell systems of Embodiments 1 and 2 described above are battery-driven systems, in order to ensure the charging capacity required for operation of the fuel cell system after startup, the control unit It is preferable to control the operation time of the hydrogen pump 8 and the air pump 15, that is, the thawing time and the flow rate of the gas circulated by these pumps 8 and 11 according to the charge capacity.
In addition, a thawing time may be set in advance in the control unit, and the warming operation may be performed for that time, or an outside air temperature sensor is provided, and the thawing time is determined according to the outside air temperature measured by the outside air temperature sensor. May be changed. Further, as described above, the state sensor for detecting the open / close state of the control valve is provided, and when the open / close state of the control valve detected by the state sensor becomes a desired open / close state, the control unit stops the warming-up operation. Then, the system may be started.

1 is a schematic diagram showing a fuel cell system according to Embodiment 1 of the present invention. It is the schematic which shows the fuel cell system which concerns on Embodiment 2 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Fuel cell main body, 2 Hydrogen flow path, 2a, 3a Main body side flow path, 2b, 3b Supply flow path, 2c, 3c Discharge flow path, 3 Air flow path, 4 High-pressure hydrogen tank, 5 1st pressure regulation valve, 6 Second pressure regulating valve, 7, 16 Back pressure regulating valve, 8 Hydrogen pump, 9, 11 Shut-off valve, 10, 17 Bypass path, 12, 21 Circulating flow path, 13 Check valve, 14 Humidification module, 15 Air pump, 18 Three-way valve.

Claims (9)

In the fuel cell system for generating power by supplying hydrogen and air to the fuel cell main body from the hydrogen flow path and the air flow path through the control valves, respectively,
At least one of the hydrogen flow path and the air flow path is
A bypass for bypassing the fuel cell body and the control valve to flow gas,
A selection means for selecting either the main body side flow path passing through the fuel cell main body or the bypass path;
Gas flow means for flowing gas through the bypass path;
During operation, the selection means selects the main body side flow path, and when the control valve is frozen, the selection means selects the bypass path and operates the gas flow means to cause the control valve to flow through the bypass path. A fuel cell system comprising: a heating control unit.   2. The fuel cell system according to claim 1, wherein the bypass passage, the selection unit, and the gas circulation unit are provided in both a hydrogen flow path and an air flow path, respectively.   The at least one gas flow path further includes a circulation flow path for circulating exhaust gas discharged from the fuel cell main body upstream of the fuel cell main body, and the circulation flow path and the bypass path when the control valve is frozen. The fuel cell system according to claim 1, wherein the selection unit and the gas circulation unit form a closed circuit.   The fuel cell system according to any one of claims 1 to 3, wherein the selection means is a shut-off valve disposed in the middle of the bypass path.   The fuel cell system according to any one of claims 1 to 3, wherein the selection unit is a three-way valve disposed at a branch point between the main body side flow path and the bypass path.   The fuel cell system according to any one of claims 1 to 5, wherein a throttle portion is formed in the bypass path.   The fuel cell system according to any one of claims 1 to 6, wherein a pipe diameter of the bypass passage is formed smaller than a pipe diameter of the gas passage.   The said control part controls the flow volume of the gas distribute | circulated by the operating time of the said gas distribution means or the said gas distribution means according to the charge capacity of a battery. The fuel cell system described.   The fuel cell system according to any one of claims 1 to 8, wherein the gas circulation means is a pump for flowing gas into the main body side channel during operation.

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