JP2003178782A - Hydrogen pump and fuel cell system using hydrogen pump - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To prevent freezing of a hydrogen pump and secure startability. SOLUTION: The fuel cell system includes a fuel cell 1 that is supplied with hydrogen gas and air to generate power, a hydrogen gas supply channel 10 that supplies hydrogen gas to the fuel cell 1, a fuel cell 1
A hydrogen off-gas circulation channel 20 for returning the hydrogen off-gas discharged from the hydrogen gas to the hydrogen gas supply channel 10, a hydrogen pump 6 disposed in the hydrogen off-gas circulation channel 20, and hydrogen from the hydrogen gas supply channel 10 to the hydrogen pump 6. A scavenging gas introduction flow path 30 for introducing gas is provided. A liquid storage part is provided in the suction part 64 and the discharge part 65 of the hydrogen pump 6. When the fuel cell system is stopped, the scavenging gas introduction valve 31 and the exhaust valve 22 are opened, and hydrogen gas having a low water content and not flowing through the fuel cell 1 is supplied to the pump chamber of the hydrogen pump 6 through the scavenging gas introduction passage 30. And purge the pump chamber.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydrogen pump for conveying hydrogen and a fuel cell system using this hydrogen pump.

[0002]

2. Description of the Related Art In a fuel cell that uses hydrogen gas and an oxidant gas as reaction gases to generate electricity, water is generated as electricity is generated.
In order to discharge this generated water from the inside of the fuel cell, hydrogen gas and oxidant gas are supplied in an amount larger than the consumption amount required for power generation. Therefore, unreacted hydrogen gas is contained in the hydrogen gas discharged from the fuel cell, that is, the hydrogen off-gas, and if this gas is released as it is, the fuel efficiency deteriorates. Therefore, in order to improve fuel economy, a fuel cell system has been devised in which this hydrogen off-gas is positively circulated as a fuel gas by using a hydrogen pump, mixed with fresh hydrogen gas and supplied again to the fuel cell.

[0003]

However, as described above, in the fuel cell, water is generated with power generation as described above, and the generated water is discharged together with the hydrogen off gas. Therefore, in the fuel cell system of the hydrogen off gas circulation type described above, The produced water is also introduced into the hydrogen pump together with the hydrogen off gas. Therefore, if the fuel cell system is left in a low temperature atmosphere after the operation of the fuel cell is stopped, the water remaining in the hydrogen pump freezes, and if the fuel cell is restarted in this frozen state, the impeller of the hydrogen pump will Problems such as damage and abnormal current flowing to the motor that drives the hydrogen pump occur.

Even when the produced water is not directly introduced into the hydrogen pump, the hydrogen off gas has high humidity,
In the above-mentioned hydrogen off-gas circulation type fuel cell system, high-humidity hydrogen off-gas is introduced into the hydrogen pump, and if the fuel cell system is left in a low temperature atmosphere after the operation of the fuel cell is stopped, it remains in the hydrogen pump. Moisture in the hydrogen off-gas may condense and freeze, causing the same problem as described above. Therefore, the present invention provides a hydrogen off-gas circulation type fuel cell system that prevents freezing in the hydrogen pump to ensure the startability of the hydrogen pump and makes this possible.

[0005]

In order to solve the above-mentioned problems, the invention described in claim 1 is a hydrogen pump for sucking in and discharging hydrogen gas (for example, a hydrogen pump 6 in an embodiment described later). Then, at least one of the suction portion (for example, the suction portion 64 in the embodiment described later) and the discharge portion (for example, the discharge portion 65 in the embodiment described later) has a liquid storage portion (for example, the suction portion 64 in the embodiment described later). Liquid storage parts 64a, 65a) in the embodiment are provided, and hydrogen gas having a lower water content than hydrogen gas flowing during operation can be flowed to the movable part (for example, pump chamber 62 in the embodiment described later) when operation is stopped. It is a possible hydrogen pump.

With this configuration, even if liquid water flows from the suction part together with hydrogen gas, the liquid water can be removed by the liquid storage part of the suction part or the liquid storage part of the discharge part. . Therefore, it becomes possible to prevent liquid water from accumulating in the movable part of the hydrogen pump. In particular, when the liquid storage part is provided in the discharge part, it becomes possible to remove the condensed water generated when the gas is compressed in the movable part during the operation of the hydrogen pump. Further, when the hydrogen pump is stopped, hydrogen gas having a low water content is caused to flow through the movable part to scavenge the movable part, thereby making the movable part an atmosphere with low humidity. The liquid storage part may be provided only in the suction part, only in the discharge part, or in both the suction part and the discharge part.

According to a second aspect of the present invention, in the first aspect of the invention, the hydrogen gas having a low water content used in the fuel cell system is a hydrogen gas that does not flow through the fuel cell. A hydrogen pump characterized by. With this configuration, the hydrogen gas that does not flow through the fuel cell has a low humidity, so that it is possible to prevent the hydrogen pump in the fuel cell system from freezing and ensure startability.

According to the third aspect of the present invention, a fuel cell (for example, a fuel cell) which is supplied with hydrogen gas and oxidant gas to generate electric power (for example,
A fuel cell 1) according to an embodiment described later, and a hydrogen gas supply channel (for example, a hydrogen gas supply channel for supplying hydrogen gas to the fuel cell)
Hydrogen gas supply channel 10 in an embodiment described later)
And a hydrogen off-gas circulation channel that returns hydrogen off-gas discharged from the fuel cell to the hydrogen gas supply channel (for example,
Hydrogen off-gas circulation channel 2 in an embodiment described later
0), a hydrogen pump which is arranged in any of the hydrogen gas supply flow path and the hydrogen off-gas circulation flow path to suck in and discharge the hydrogen gas, the hydrogen gas having a lower water content than the hydrogen gas flowing during operation. A fuel cell system comprising: a hydrogen pump (for example, a hydrogen pump 6 in an embodiment described later) that can flow to a movable part when the operation is stopped. With this configuration, it is possible to introduce hydrogen gas having a low water content into the moving part of the hydrogen pump when the fuel-fuel cell system is stopped, and to make the moving part of the hydrogen pump have a low-humidity atmosphere. Become.

According to a fourth aspect of the invention, a fuel cell (for example, a hydrogen gas and an oxidant gas are supplied to generate power) (for example,
A fuel cell 1) according to an embodiment described later, and a hydrogen gas supply channel (for example, a hydrogen gas supply channel for supplying hydrogen gas to the fuel cell)
Hydrogen gas supply channel 10 in an embodiment described later)
And a hydrogen off-gas circulation channel that returns hydrogen off-gas discharged from the fuel cell to the hydrogen gas supply channel (for example,
Hydrogen off-gas circulation channel 2 in an embodiment described later
0), and the hydrogen pump according to claim 2 disposed in any one of the hydrogen gas supply passage and the hydrogen off-gas circulation passage (for example, the hydrogen pump 6 in the embodiment described later).
And a fuel cell system. With this configuration, it is possible to prevent liquid water from accumulating in the moving part of the hydrogen pump during operation of the fuel cell system, and to prevent water content in the moving part of the hydrogen pump when the fuel fuel cell system is stopped. By introducing a small amount of hydrogen gas, it becomes possible to make the moving part of the hydrogen pump an atmosphere of low humidity.

According to a fifth aspect of the present invention, in the invention according to the third or fourth aspect, an exhaust means for discharging the gas flowing through the hydrogen off gas circulation passage (for example, in an embodiment described later). Exhaust valve 22, exhaust flow path 23) and scavenging gas introduction means (for example, scavenging gas introduction flow in an embodiment described later) that can introduce hydrogen gas flowing through the hydrogen gas supply flow path into a movable part of the hydrogen pump. A passage 30, a scavenging gas introduction valve 31), and scavenging control means for scavenging the inside of the hydrogen pump by controlling the exhaust means and the scavenging gas introduction means when stopping the fuel cell.
It is characterized by including. With this configuration, after the hydrogen pump is stopped, the exhaust unit and the scavenging gas introduction unit are controlled so that the hydrogen gas with low humidity that does not flow to the fuel cell can be moved from the hydrogen gas supply channel to the hydrogen pump. It is possible to introduce the gas into the section and scavenging the movable section of the hydrogen pump to seal the inside of the movable section with hydrogen gas having low humidity.

According to a sixth aspect of the present invention, in the invention according to the fifth aspect, a shutoff valve is provided upstream and downstream of the hydrogen pump and capable of shutting off gas flow in and out of the hydrogen pump (for example, described later. The present invention is characterized by including an inlet shutoff valve 25 and an outlet shutoff valve 26) in the embodiment, and a sealing control means for closing the shutoff valve after completion of scavenging of the hydrogen pump. With this configuration, it is possible to close the shutoff valve after the completion of the scavenging of the hydrogen pump to shut off the flow of gas into and out of the hydrogen pump, and the water held by the fuel cell, etc., while the fuel cell system is stopped. It is possible to prevent the hydrogen pump from entering the moving part.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a hydrogen pump and a fuel cell system using the hydrogen pump according to the present invention will be described below with reference to the drawings of FIGS. 1 to 15. [First Embodiment] First, a first embodiment of the present invention will be described with reference to the drawings of FIGS. Figure 1
FIG. 1 is a schematic configuration diagram of a fuel cell system according to a first embodiment. The fuel cell 1 comprises a stack composed of a plurality of cells formed by sandwiching a solid polymer electrolyte membrane, such as a solid polymer ion exchange membrane, between an anode and a cathode from both sides. When hydrogen gas is supplied and air containing oxygen as an oxidant gas is supplied to the cathode, hydrogen ions generated by the catalytic reaction at the anode move to the cathode through the solid polymer electrolyte membrane and become oxygen at the cathode. Electrochemical reaction causes electricity to generate water.

Air is pressurized to a predetermined pressure by the compressor 2 and supplied to the cathode of the fuel cell 1. After this air is used for power generation, it is discharged from the fuel cell 1 as air off gas and discharged via the pressure control valve 3. on the other hand,
The hydrogen gas supplied from the high-pressure hydrogen tank 4 is depressurized to a predetermined pressure by a pressure control valve 5 provided in the hydrogen gas supply passage 10 and supplied to the anode of the fuel cell 1. The hydrogen gas supplied to the fuel cell 1 is used for power generation, and then discharged from the fuel cell 1 to the hydrogen off gas circulation flow path 20 as hydrogen off gas. Hydrogen off-gas circulation channel 20
Is connected to a hydrogen gas supply passage 10 downstream of the pressure control valve 5, and a hydrogen pump 6 and a check valve 21 are provided in the middle of the hydrogen off-gas circulation passage 20. The hydrogen off-gas discharged from the fuel cell 1 is pressurized by the hydrogen pump 6 and merges with the hydrogen gas supply passage 10 through the check valve 21. As a result, the hydrogen off-gas is
It is mixed with fresh hydrogen gas supplied from the high-pressure hydrogen tank 4 and supplied again to the anode of the fuel cell 1.

The hydrogen pump 6 will be described with reference to FIGS. 2 and 3. 2 is a vertical sectional view of the hydrogen pump 6 as seen from the front side, and FIG. 3 is a sectional view taken along the line III-III of FIG. The hydrogen pump 6 is, for example, a so-called Wesco type pump, and includes a pump chamber (movable part) 62 of the pump casing 61.
Inside, the impeller 63 driven by the motor rotates to increase the pressure of the hydrogen off gas and deliver it. At the lower end of the pump casing 61, there are provided a suction part 64 for introducing hydrogen off-gas into the pump chamber 62 and a discharge part 65 for discharging the hydrogen off-gas pressurized in the pump chamber 62. The parts 65 are the liquid storage parts 64, respectively.
a and 65a. The hydrogen off-gas circulation channel 20 is connected to the suction section 64 and the discharge section 65.

A scavenging gas introducing portion 66 for introducing hydrogen gas into the pump chamber 62 at the time of pump scavenging, which will be described later, is provided at the upper end of the pump casing 61. Figure 1
As shown in, the scavenging gas introduction unit 66 is connected to the hydrogen gas supply passage 10 via a scavenging gas introduction passage 30 provided with a scavenging gas introduction valve 31 on the way. In the hydrogen gas supply passage 10, a branch portion A to the scavenging gas introduction passage 30
Is located downstream of the pressure control valve 5 and upstream of the junction B with the hydrogen off-gas circulation flow path 20. Further, an exhaust flow path 23 including an exhaust valve 22 is connected to the hydrogen off-gas circulation flow path 20 on the upstream side of the hydrogen pump 6. The scavenging gas introduction valve 31 and the exhaust valve 22 are controlled to be opened and closed by a control device (hereinafter abbreviated as ECU) 50. In the first embodiment, the exhaust valve 22 and the exhaust flow path 23 form an exhaust means, and the scavenging gas introduction flow path 30 and the scavenging gas introduction valve 31 form a scavenging gas introduction means.

In this fuel cell system, the hydrogen off-gas discharged from the fuel cell 1 during the power generation by the fuel cell 1 has extremely high humidity, and the water produced in the fuel cell 1 due to the power generation is mixed. In some cases. However, in this fuel cell system, since the suction part 64 of the hydrogen pump 6 is provided with the liquid storage part 64a,
Most of the liquid water contained in the hydrogen off-gas falls into the liquid storage part 64a and is removed when passing through the suction part 64, so that the hydrogen off-gas containing almost no liquid water in the pump chamber 62 of the hydrogen pump 6. Will be introduced.

In addition, a slight amount of liquid water introduced into the pump chamber 62 without falling into the liquid storage portion 64a of the suction portion 64 or hydrogen off gas is compressed while being sent to the discharge portion 65 in the pump chamber 62. When the condensed water thus generated passes through the discharge part 65 of the hydrogen pump 6, the condensed water falls into the liquid storage part 65 a provided in the discharge part 65 and is removed. Therefore, during operation of the fuel cell system, the pump chamber 62
Since there is almost no liquid water in the fuel cell system, even if the hydrogen pump 6 is stopped by stopping the fuel cell system thereafter, it is possible to make the liquid chamber not exist in the pump chamber 62. Even if the system is left in a low-temperature atmosphere after the stop of step 1, the hydrogen pump 6 can be prevented from freezing. As a result, it is possible to secure the startability of the hydrogen pump 6 when the operation of the fuel cell system is restarted, and it is possible to improve the durability of the hydrogen pump 6.

Thus, in this fuel cell system,
The liquid storage parts 64a, 65 are provided in the suction part 64 and the discharge part 65
Since the hydrogen pump 6 provided with a is used, it is possible to prevent the hydrogen pump 6 from freezing. However, when the fuel cell system is stopped, the high-humidity hydrogen off-gas remains in the hydrogen pump 6. If so, the water in the hydrogen off-gas remaining in the pump chamber 62 may be condensed in a low temperature atmosphere, and the condensed water may be frozen to freeze the hydrogen pump 6.

Therefore, in this fuel cell system, when the hydrogen pump 6 is stopped when the system is shut down, the scavenging gas introduction valve 31 and the exhaust valve 22 are opened so that the hydrogen before flowing into the fuel cell 1 can be obtained. The dry (low humidity) hydrogen gas flowing through the gas supply flow path 10 is introduced into the pump chamber 62 of the hydrogen pump 6, and the high-humidity hydrogen off-gas remaining in the pump chamber 62 is pushed out by the dry hydrogen gas and scavenged. However, the inside of the pump chamber 62 is replaced with dry hydrogen gas. In this way, even if the fuel cell system is left in a low temperature atmosphere after stopping,
The freezing of the hydrogen pump 6 can be prevented more reliably,
The startability of the hydrogen pump 6 when the operation of the fuel cell system is restarted can be reliably ensured, and the durability of the hydrogen pump 6 can be further improved.

Next, the scavenging process control of the fuel cell system according to the first embodiment will be described with reference to the flowchart of FIG. The hydrogen pump 6 is stopped when the system shutdown of the fuel cell system is started (step S10).
1), a system hydrogen purge start command is issued (step S
102). By this system hydrogen purge start command, the scavenging gas introduction valve 31 and the exhaust valve 22 are opened (step S10).
3). As a result, a part of the dry hydrogen gas supplied from the high-pressure hydrogen tank 1 is partially separated from the branch portion A downstream of the pressure control valve 5.
From the scavenging gas introduction passage 30 and the scavenging gas introduction valve 31.
And is introduced into the pump chamber 62 through the scavenging gas introduction part 66 of the hydrogen pump 6. The dry hydrogen gas introduced into the pump chamber 62 flows through the space between the inner surface of the pump chamber 62 and the stopped impeller 61 to the suction portion 64, and the hydrogen off-gas remaining in the pump chamber 62. Extrude,
Is discharged from the suction section 64 to the hydrogen off-gas circulation flow path 20,
Further, it is discharged to the outside of the system through the exhaust passage 23 and the exhaust valve 22.

At the same time, the rest of the dry hydrogen gas supplied from the high-pressure hydrogen tank 1 is supplied to the anode of the fuel cell 1 through the same flow path as when the fuel cell system is operating, and The hydrogen off-gas remaining in the anode is pushed out, discharged from the fuel cell 1, passed through the hydrogen off-gas circulation flow path 20, further discharged through the exhaust flow path 23 and the exhaust valve 22 to the outside of the system. In addition, in FIG. 1, thick solid arrows indicate the flow direction of hydrogen gas during the operation of the fuel cell 1, and do not indicate the flow direction of gas during the scavenging process.

Next, in step S104, it is determined whether or not a predetermined time has elapsed since the system purge start command was issued. If the result of the determination is "NO" (not elapsed), the scavenging gas introduction valve 31 Then, the exhaust valve 22 is held open, and the process returns to step S104. If the determination result in step S104 is “YES” (elapse of a predetermined time), the process proceeds to step S105, and the scavenging gas introduction valve 31 and the exhaust valve 22 are performed.
To close the execution of this routine.

As described above, in the first embodiment,
The steps from step S101 to step S105 are
Realize scavenging control means. In the first embodiment, an ejector that sucks the hydrogen off gas boosted by the hydrogen pump 6 and mixes it with the hydrogen gas is provided at the confluence B of the hydrogen gas supply channel 10 and the hydrogen off gas circulation channel 20. It is also possible to do so.

Second Embodiment Next, a second embodiment of the hydrogen pump and the fuel cell system according to the present invention will be described with reference to the drawings of FIGS. 5 and 6. FIG. 5 is a schematic configuration diagram of the fuel cell system according to the second embodiment. The fuel cell system according to the second embodiment differs from that of the first embodiment (FIG. 1) in that
Hydrogen off-gas circulation flow path 20 upstream of the hydrogen pump 6
In addition, a dew point meter 24 for detecting the dew point of the gas flowing through the hydrogen off-gas circulation flow path 20 is provided, and other configurations are the same as those of the first embodiment including the hydrogen pump 6. Therefore, the same reference numerals are given to the same aspect parts and the description thereof will be omitted. The dew point meter 24 outputs an output signal to the ECU 50 according to the detected dew point of the gas.

In the second embodiment, the dew point of the gas discharged from the suction section 64 of the hydrogen pump 6 (in other words, the dryness of the gas) is detected and detected during execution of the scavenging process. The scavenging process is terminated when the dew point of the gas becomes equal to or lower than a predetermined value. FIG. 6 is a flowchart of scavenging process control in the fuel cell system according to the second embodiment, and the only difference from the scavenging process according to the first embodiment is step S104. In this step S104, it is determined whether or not the dew point of the gas discharged from the suction section 64 of the hydrogen pump 6 is below a predetermined value.

The determination result in step S104 is "N.
If it is "O" (exceeds a predetermined value), the scavenging gas introduction valve 31 and the exhaust valve 22 are held open, and step S
Return to 104. If the determination result in step S104 is "YES" (less than or equal to a predetermined value), step S1
In step 05, the scavenging gas introduction valve 31 and the exhaust valve 22 are closed, and the execution of this routine ends. According to the fuel cell system of the second embodiment, the atmosphere inside the pump chamber 62 of the hydrogen pump 6 can be surely made to be equal to or lower than the predetermined dryness. Therefore, the hydrogen pump 6 can be more reliably prevented from freezing, and the fuel cell system can be reliably restarted.

[Third Embodiment] Next, a third embodiment of the hydrogen pump and the fuel cell system according to the present invention will be described with reference to the drawing of FIG. FIG. 7 is a schematic configuration diagram of the fuel cell system according to the third embodiment. The fuel cell system of the third embodiment is different from that of the first embodiment (aspect of FIG. 1) in the following points.
The hydrogen pump 6 in the third embodiment is not provided with the scavenging gas introducing section 66, and the fuel cell system in the third embodiment is not provided with the scavenging gas introducing passage 30. Then, the hydrogen off-gas circulation channel 20
In place of the check valve 21, a scavenging gas introduction valve 31 whose opening / closing is controlled by the ECU 50 is provided. This third
In the case of the above embodiment, the scavenging gas introducing means is constituted by the scavenging gas introducing valve 31.

The scavenging gas introduction valve 31 is controlled to be opened by the ECU 50 when the hydrogen off gas is circulated during the operation of the fuel cell 1 so that the hydrogen off gas is supplied from the hydrogen off gas circulation flow path 20 to the hydrogen gas supply flow path. Circulate to 10. Further, the scavenging gas introduction valve 31 is controlled to be opened even during the scavenging process after the fuel cell system is shut down, so that the dry hydrogen gas supplied from the high-pressure hydrogen tank 4 is discharged from the discharge part 65 of the hydrogen pump 6 to the pump chamber. 62, the hydrogen off-gas having a high humidity remaining in the pump chamber 62 is discharged from the suction part 64 to the hydrogen off-gas circulation flow path 20 for scavenging, and discharged to the outside of the system through the exhaust valve 22 and the exhaust flow path 23. To do. Then, the inside of the pump chamber 62 is replaced with dry hydrogen gas. Since other configurations are the same as those of the first embodiment, the same reference numerals are given to the same aspect parts and the description thereof will be omitted. Also in the fuel cell system of the third embodiment, like the first embodiment, even if the system is left in a low temperature atmosphere after the fuel cell system is stopped, the hydrogen pump 6 is prevented from freezing. As a result, the startability of the hydrogen pump 6 when the operation of the fuel cell system is restarted can be ensured, and the durability of the hydrogen pump 6 can be improved. Moreover, the first
The system configuration can be simplified as compared with the case of the embodiment.

[Fourth Embodiment] Next, a hydrogen pump and a fuel cell system according to a fourth embodiment of the present invention will be described with reference to the drawings of FIGS. 8 and 9. FIG. 8 is a schematic configuration diagram of the fuel cell system according to the fourth embodiment. The fuel cell system of the fourth embodiment is different from that of the third embodiment (aspect of FIG. 7) in the following points. An ejector 7A is arranged at the confluence of the hydrogen gas supply channel 10 and the hydrogen off-gas circulation channel 20,
An ejector cutoff valve 8 is arranged in the hydrogen gas supply passage 10 downstream of the ejector 7A. Further, the hydrogen gas supply passage 10 is connected with a bypass passage 11A that bypasses the ejector 7A and the ejector cutoff valve 8, and a bypass pressure control valve 12A is arranged in the bypass passage 11A.

The ejector 7A sucks the hydrogen off-gas boosted by the hydrogen pump 6 by the negative pressure generated by the jet flow of the fuel gas supplied to the ejector 7A from the hydrogen gas supply passage 10, mixes the two and sends them out. To do. The ejector cutoff valve 8 is opened when the fuel cell system is in operation and closed when the system is shut down.
The opening and closing is controlled by. The rest of the configuration including the hydrogen pump 6 is the same as that of the third embodiment, and therefore, the same symbols are given to the same mode parts and the description is omitted.

Next, scavenging process control in the fuel cell system according to the fourth embodiment will be described with reference to the flowchart of FIG. The hydrogen pump 6 is stopped by starting the system shutdown of the fuel cell system (step S
201), and a system hydrogen purge start command is issued (step S202). With this system hydrogen purge start command, the scavenging gas introduction valve 31 and the exhaust valve 22 are opened, and
The ejector cutoff valve 8 is closed (step S203). As a result, a part of the dry hydrogen gas supplied from the high-pressure hydrogen tank 1 is partially discharged from the ejector 7A into the hydrogen off gas circulation flow path 2
0 and the scavenging gas introduction valve 31 and backflow from the discharge portion 65 of the hydrogen pump 6 to the pump chamber 62, and the high-humidity hydrogen offgas remaining in the pump chamber 62 is discharged from the suction portion 64 to the hydrogen offgas circulation flow passage 20. Then, the gas is scavenged and discharged to the outside of the system through the exhaust valve 22 and the exhaust flow path 23. And
The inside of the pump chamber 62 is replaced with dry hydrogen gas.

At the same time, the remaining dry hydrogen gas supplied from the high-pressure hydrogen tank 1 remains in the bypass passage 1.
1A and a bypass valve 12A are supplied to the anode of the fuel cell 1, the hydrogen off-gas remaining in the anode of the fuel cell 1 is pushed out, discharged from the fuel cell 1, passed through the hydrogen off-gas circulation flow path 20, and further exhausted. It is discharged to the outside of the system through the flow path 23 and the exhaust valve 22. Note that FIG.
In, the thick solid line arrow indicates the flow direction of hydrogen gas during the operation of the fuel cell 1, and does not indicate the flow direction of gas during the scavenging process.

Next, in step S204, it is determined whether or not a predetermined time has elapsed since the system purge start command was issued. If the determination result is "NO" (not elapsed), the scavenging gas introduction valve 31 Then, the exhaust valve 22 and the ejector cutoff valve 8 are kept open and the routine returns to step S204. The determination result in step S204 is “YES”
In the case of (elapse of a predetermined time), the process proceeds to step S205, the scavenging gas introduction valve 31 and the exhaust valve 22 are closed, and the execution of this routine ends.

In the fourth embodiment, step S2
The steps from 01 to S205 implement the scavenging control means. Note that, also in the fourth embodiment,
A dew point meter may be arranged in the hydrogen off-gas circulation flow path 20 to detect the dew point of the gas during the scavenging process, and complete the scavenging process when the dew point of the gas falls below a predetermined value. In the fuel cell system according to the fourth embodiment, as in the first embodiment, even if the system is left in a low temperature atmosphere after the fuel cell system is stopped, the hydrogen pump 6
Can be prevented, and as a result, the startability of the hydrogen pump 6 when the operation of the fuel cell system is restarted can be ensured, and the durability of the hydrogen pump 6 can be improved.

[Fifth Embodiment] Next, a fifth embodiment of the hydrogen pump and the fuel cell system according to the present invention will be described with reference to the drawings of FIGS. 10 and 11. Figure 10
FIG. 9 is a schematic configuration diagram of a fuel cell system according to a fifth embodiment. The fuel cell system according to the fifth embodiment differs from that of the second embodiment (aspect of FIG. 5) in the following points. The hydrogen gas supply flow passage 10 is provided with an ejector 7B at a confluence with the hydrogen off-gas circulation flow passage 20 and is connected with a bypass flow passage 11B that bypasses the ejector 7B. A pressure control valve 12B is arranged. Further, the hydrogen gas supply passage 10 on the downstream side of the ejector 7B
In addition, the anode humidifier 13 that humidifies the hydrogen gas supplied to the anode of the fuel cell 1 is disposed on the downstream side of the confluence portion with the bypass flow passage 11B.

Further, in the fuel cell system according to the fifth embodiment, the check valve 21 is not arranged in the hydrogen off gas circulation flow passage 20. Further, in the hydrogen off-gas circulation flow path 20, an inlet cutoff valve 25 and an outlet cutoff valve 26, which are controlled to open / close by the ECU 50, are arranged upstream of the dew point meter 24 and downstream of the hydrogen pump 6. The rest of the configuration including the hydrogen pump 6 is the same as that of the second embodiment, and therefore, the same symbols are given to the same mode parts and the description is omitted.

In the fuel cell system according to the fifth embodiment, after shutting down the fuel cell system, after scavenging the inside of the fuel cell 1 and the inside of the hydrogen pump 6, the inlet shutoff valve 25 and the outlet shutoff valve 26 are closed. This prevents the gas from entering and leaving the hydrogen pump 6. The reason for doing this is as follows. Even if the inside of the system is scavenged after the fuel cell system is shut down, the fuel cell 1 and the anode humidifier 13 retain the residual moisture, and if the hydrogen pump 6 is not sealed, the fuel cell 1 and the anode humidifier 13 are The remaining residual water and the like may diffuse and enter the hydrogen pump 6, which may freeze and cause the hydrogen pump 6 to freeze. However,
In the case of the fifth embodiment, by closing the inlet shutoff valve 25 and the outlet shutoff valve 26, it is possible to shut off the flow of gas into and out of the hydrogen pump 6, so that the dry gas introduced into the hydrogen pump 6 is introduced. The hydrogen gas can be sealed in the hydrogen pump 6 to prevent moisture from entering from the outside, and as a result, the freezing of the hydrogen pump 6 can be completely prevented. Therefore, the startability of the hydrogen pump 6 when the operation of the fuel cell system is restarted can be reliably ensured, and the durability of the hydrogen pump 6 can be further improved. The inlet shutoff valve 25 and the outlet shutoff valve 26 are open during the operation of the fuel cell system.

Next, scavenging process control in the fuel cell system according to the fifth embodiment will be described with reference to the flowchart of FIG. When the system shutdown of the fuel cell system is started, the hydrogen pump 6 is stopped (step S301), and a system hydrogen purge start command is issued (step S302). By the system hydrogen purge start command, the scavenging gas introduction valve 31 and the exhaust valve 22 are opened (step S303). As a result, a part of the dry hydrogen gas supplied from the high-pressure hydrogen tank 1 passes through the scavenging gas introduction flow passage 30 and the scavenging gas introduction valve 31 from the branch portion A downstream of the pressure control valve 5, and passes through the hydrogen pump 6 It is introduced into the pump chamber 62 via the scavenging gas introduction part 66. The dry hydrogen gas introduced into the pump chamber 62 flows through the space between the inner surface of the pump chamber 62 and the stopped impeller 61 to the suction portion 64, and the hydrogen off-gas remaining in the pump chamber 62. Is discharged to the outside of the system through the inlet cutoff valve 25, the exhaust flow path 23, and the exhaust valve 22.

At the same time, the remaining dry hydrogen gas supplied from the high-pressure hydrogen tank 1 remains in the bypass passage 1.
1B and the bypass valve 12B, and further through the anode humidifier 13, is supplied to the anode of the fuel cell 1, and the hydrogen off-gas remaining in the anode humidifier 13 and the anode of the fuel cell 1 is pushed out and discharged from the fuel cell 1. After passing through the hydrogen off-gas circulation flow path 20, the exhaust flow path 23 and the exhaust valve 22 are discharged to the outside of the system. In addition, in FIG. 10, thick solid arrows indicate the flow direction of hydrogen gas during the operation of the fuel cell 1,
It does not show the gas flow direction during the scavenging process.

Next, in step S304, it is determined whether or not the dew point of the gas discharged from the suction section 64 of the hydrogen pump 6 is below a predetermined value. If the determination result in step S304 is "NO" (exceeds the predetermined value), the scavenging gas introduction valve 31 and the exhaust valve 22 are held in the open state, and the process returns to step S304. If the determination result in step S304 is “YES” (equal to or less than the predetermined value), the flow advances to step S305 to close the scavenging gas introduction valve 31, the exhaust valve 22, the inlet cutoff valve 25, and the outlet cutoff valve 26, and then the routine of this routine is executed. Finish execution. As a result, the hydrogen pump 6 can be confined in the closed flow path formed between the inlet shutoff valve 25 and the outlet shutoff valve 26, and the dry hydrogen gas in the pump chamber 62 of the hydrogen pump 6 can be shut down during the system shutdown. Can be sealed. In the fifth embodiment, step S
The steps 301 to S305 realize the scavenging control means and the sealing control means.

In the fuel cell systems of the above-described first to fifth embodiments, the hydrogen pump 6 having the liquid storage parts 64a and 65a in the suction part 64 and the discharge part 65 is used as an example. However, the liquid storage parts 64a and 65a
The fuel cell system of the present invention is established even when a hydrogen pump that does not include the above is used. In that case, it is unavoidable to introduce liquid water into the hydrogen pump during operation of the fuel cell system, but even if the liquid water introduced into the hydrogen pump during operation may slightly accumulate, After stopping
By performing the scavenging process of the pump chamber (movable part) of the hydrogen pump with hydrogen gas having low humidity, liquid water in the pump chamber can be discharged to the outside of the system, and the inside of the pump chamber can be made into a low humidity atmosphere. be able to. Therefore, even if the system is left in a low temperature atmosphere after the fuel cell system is stopped, the hydrogen pump 6 can be prevented from freezing, and as a result, the startability of the hydrogen pump 6 can be secured when the operation of the fuel cell system is restarted. In addition, the durability of the hydrogen pump 6 can be improved.

[Sixth Embodiment] Next, a sixth embodiment of the hydrogen pump and the fuel cell system according to the present invention will be described with reference to the drawings of FIGS. 12 and 13. 12
FIG. 9 is a schematic configuration diagram of a fuel cell system according to a sixth embodiment. The fuel cell system of the sixth embodiment is different from that of the first embodiment (aspect of FIG. 1) in the following points.

The hydrogen pump 6 according to the sixth embodiment is not provided with the scavenging gas introducing portion 66, and the fuel cell system according to the sixth embodiment has the scavenging gas introducing passage 30 and the scavenging gas introducing portion. The valve 31 is not provided. A drainage flow path 28 having a discharge valve 27 that is controlled to be opened and closed by the ECU 50 is connected to the bottoms of the liquid storage sections 64a and 65a of the suction section 64 and the discharge section 65 of the hydrogen pump 6. Reference numeral 28 is connected to the exhaust flow path 23 on the downstream side of the exhaust valve 22. Since other configurations are the same as those of the first embodiment, the same reference numerals are given to the same aspect parts and the description thereof will be omitted.

In the fuel cell system according to the sixth embodiment, after the fuel cell system is shut down, the inside of the fuel cell 1 and the hydrogen pump 6 are scavenged, and at the same time, the discharge valve 27 is opened to open the liquid storage parts 64a, 65a. The water stored in is drained. By completely draining the stored water in this way, it is possible to complete the preparation for receiving the liquid to be removed from the hydrogen off-gas at the time of the next operation of the fuel cell system and store the liquid. The discharge valve 27 is closed when the fuel cell system is operating.

Next, scavenging process control in the fuel cell system according to the sixth embodiment will be described with reference to the flowchart of FIG. When the system shutdown of the fuel cell system is started, the hydrogen pump 6 is stopped (step S401), and a system hydrogen purge start command is issued (step S402). By this system hydrogen purge start command, the exhaust valve 27 and the exhaust valve 22 are opened (step S40).
3). As a result, the dry hydrogen gas supplied from the high-pressure hydrogen tank 1 is supplied to the anode of the fuel cell 1 through the hydrogen gas supply passage 10, and the hydrogen off-gas remaining in the anode of the fuel cell 1 is pushed out to remove the fuel. It is discharged from the battery 1 and is discharged to the outside of the system through the hydrogen off-gas circulation flow path 20, the exhaust flow path 23, and the exhaust valve 22. At this time, the liquid stored in the liquid storage parts 64a and 65a of the suction part 64 and the discharge part 65 is sucked into the discharge flow path 28 and discharged from the exhaust flow path 23 to the outside of the system through the discharge valve 27.

A part of the dry hydrogen gas discharged from the fuel cell 1 to the hydrogen off-gas circulation passage 20 is introduced into the pump chamber 62 from the suction portion 64 of the hydrogen pump 6, and the inner surface of the pump chamber 62 The hydrogen off-gas remaining in the hydrogen pump 6 is pushed out and scavenged by flowing through the gap between the impellers 61 being stopped to the discharge portion 65, and is discharged to the outside of the system through the exhaust passage 28 and the discharge valve 27. Is discharged. In FIG. 8, thick solid arrows indicate the flow direction of hydrogen gas during the operation of the fuel cell 1, not the flow direction of gas during the scavenging process.

Next, in step S404, it is determined whether or not a predetermined time has passed since the system purge start command was issued. If the determination result is "NO" (not passed), the exhaust valve 27 and the exhaust gas are exhausted. Hold the valve 22 in the open state and perform step S
Return to 404. If the determination result in step S404 is "YES" (elapse of a predetermined time), step S404
Proceeding to 405, the exhaust valve 27 and the exhaust valve 22 are closed, and the execution of this routine ends.

Also in the fuel cell system of the sixth embodiment, as in the first embodiment, the inside of the pump chamber 62 of the hydrogen pump 6 can be made to have a low humidity atmosphere, so that the fuel cell system Even if the system is left in a low temperature atmosphere after the stop, the hydrogen pump 6 can be prevented from freezing, and as a result, the startability of the hydrogen pump 6 can be secured when the operation of the fuel cell system is restarted. The durability of the hydrogen pump 6 can be improved.

In the sixth embodiment, the hydrogen off-gas boosted by the hydrogen pump 6 is sucked into the confluence B of the hydrogen gas supply passage 10 and the hydrogen off-gas circulation passage 20 and mixed with the hydrogen gas. It is also possible to arrange an ejector.

[Seventh Embodiment] Next, a seventh embodiment of the hydrogen pump and the fuel cell system according to the present invention will be described with reference to the drawings of FIGS. 14 and 15. 14
FIG. 9 is a schematic configuration diagram of a fuel cell system according to a seventh embodiment. The fuel cell system of the seventh embodiment is different from that of the sixth embodiment (aspect of FIG. 12) in the following points.

Suction portion 64 and discharge portion 6 of hydrogen pump 6
5 to the liquid storage parts 64a and 65a,
A liquid level sensor 67 for detecting the liquid level of 65a is provided. The rest of the configuration is the same as that of the sixth embodiment including the hydrogen pump 6, so the same reference numerals are given to the same aspects and the description thereof is omitted. In the sixth embodiment described above, the drainage treatment of the liquid storage parts 64a and 64b was executed in synchronization with the scavenging treatment of the hydrogen pump 6, but in the seventh embodiment, the drainage treatment is changed from the scavenging treatment. Independently, based on the liquid level detected by the liquid level sensor 67, the drainage process of the liquid reservoirs 64a and 64b is started and completed. Thereby, the liquid reservoir 64
Liquids a and 64b can always be stored. The liquid level sensor 67 outputs an output signal according to the detected liquid level to the ECU.
Output to 50.

Wastewater treatment control in the fuel cell system according to the seventh embodiment will be described with reference to the flowchart of FIG. In step S501, it is determined whether the liquid level detected by the liquid level sensor 67 is equal to or higher than the upper limit value. If the determination result is "NO" (less than the upper limit value), the process returns. The determination result in step S501 is "YES".
If it is (equal to or more than the upper limit value), the process proceeds to step S502, and the discharge valve 27 is opened. Next, in step S503, it is determined whether or not the liquid level detected by the liquid level sensor 67 is less than or equal to the lower limit value. If the determination result is "NO" (exceeds the lower limit value), the discharge valve 27 Hold the open state and step S
Return to 503. If the determination result in step S503 is "YES" (lower limit value or less), step S5
The routine proceeds to 04, closes the discharge valve 27, and returns. By controlling the discharge valve 27 in this manner, the liquid storage unit 6
The liquid levels of 4a and 64b can be controlled between the upper limit value and the lower limit value, and the liquid can always be held in a storable state.

In the fuel cell system of the sixth and seventh embodiments described above, a scavenging gas introduction flow path 30 and a scavenging gas introduction valve 31 are added as in the first embodiment. Then, the gas flow during the scavenging process may be the same as in the first embodiment.

[0054]

As described above, according to the invention described in claim 1, it is possible to prevent liquid water from accumulating in the moving part of the hydrogen pump, and to scavenge the moving part when the hydrogen pump is stopped. However, since it is possible to make the moving part have a low humidity atmosphere, even if the hydrogen pump is left in a low temperature atmosphere after the fuel cell system is stopped, it is possible to prevent the hydrogen pump from freezing. The excellent effect that the startability can be ensured is exhibited.

According to the second aspect of the invention, it is possible to prevent the hydrogen pump in the fuel cell system from freezing and ensure the startability, so that the startability of the fuel cell system is improved. The effect is played. According to the invention described in claim 3 or 4, it is possible to prevent the hydrogen pump used in the fuel cell system from freezing, so that the startability of the hydrogen pump, and hence the startability of the fuel cell system, can be improved. The excellent effect that it can be ensured is exhibited.

According to the invention described in claim 5, hydrogen gas having a low humidity which does not flow through the fuel cell is introduced into the hydrogen pump from the hydrogen gas supply passage, and the moving part of the hydrogen pump is scavenged to move the inside of the moving part. It is possible to replace hydrogen with low-humidity hydrogen gas, so it is possible to prevent the hydrogen pump from freezing, and as a result, it is possible to reliably ensure the startability of the hydrogen pump and, in turn, the startability of the fuel cell system. It has an excellent effect that it can be done.

According to the sixth aspect of the present invention, it is possible to prevent the water held by the fuel cell and the like from entering the movable part of the hydrogen pump while the fuel cell system is stopped. The excellent effect that the startability, and eventually the startability of the fuel cell system, can be ensured is exhibited.

[Brief description of drawings]

FIG. 1 is a system configuration diagram in a first embodiment of a fuel cell system according to the present invention.

FIG. 2 is a vertical cross-sectional view of the hydrogen pump used in the first embodiment.

3 is a sectional view taken along the line III-III of FIG.

FIG. 4 is a flowchart of scavenging process control in the first embodiment.

FIG. 5 is a system configuration diagram in a second embodiment of a fuel cell system according to the present invention.

FIG. 6 is a flowchart of scavenging process control in the second embodiment.

FIG. 7 is a system configuration diagram in a third embodiment of a fuel cell system according to the present invention.

FIG. 8 is a system configuration diagram in a fourth embodiment of a fuel cell system according to the present invention.

FIG. 9 is a flowchart of scavenging process control in the fourth embodiment.

FIG. 10 is a system configuration diagram in a fifth embodiment of a fuel cell system according to the present invention.

FIG. 11 is a flowchart of scavenging process control in the fifth embodiment.

FIG. 12 is a system configuration diagram in a sixth embodiment of a fuel cell system according to the present invention.

FIG. 13 is a flowchart of scavenging process control in the sixth embodiment.

FIG. 14 is a system configuration diagram of a fuel cell system according to a seventh embodiment of the present invention.

FIG. 15 is a flowchart of wastewater treatment control in the seventh embodiment.

[Explanation of symbols]

1 fuel cell 6 hydrogen pump 10 Hydrogen gas supply channel 20 Hydrogen off gas circulation channel 22 Exhaust valve (exhaust means) 23 Exhaust flow path (exhaust means) 30 Scavenging gas introduction flow path (scavenging gas introduction means) 31 scavenging gas introduction valve 31 (scavenging gas introduction means) 25 Inlet shutoff valve (shutoff valve) 26 Outlet shutoff valve (shutoff valve) 62 Pump room (movable part) 64 Suction part 64a Liquid storage section 65 Discharge part 65a Liquid storage section

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F04B 39/12 101 F04B 39/12 101A 41/00 41/00 BF term (reference) 3H003 AA06 AC01 BF00 CD01 CD05 3H076 BB03 CC92 CC93 CC94 CC95 5H027 AA06 BA13 BA19

Claims (6)

[Claims] 1. A hydrogen pump for sucking and discharging hydrogen gas, wherein a liquid storage part is provided in at least one of the suction part and the discharge part, and the hydrogen content is lower than that of hydrogen gas flowing during operation. A hydrogen pump that allows gas to flow to moving parts when operation is stopped. 2. The hydrogen pump according to claim 1, wherein the hydrogen gas having a low water content used in a fuel cell system is a hydrogen gas that does not flow through the fuel cell. 3. A fuel cell that is supplied with hydrogen gas and an oxidant gas to generate electricity, a hydrogen gas supply channel that supplies hydrogen gas to the fuel cell, and a hydrogen off gas discharged from the fuel cell. A hydrogen off-gas circulation channel that returns to the hydrogen gas supply channel, and a hydrogen pump that is arranged in any of the hydrogen gas supply channel and the hydrogen off-gas circulation channel and that sucks in and discharges hydrogen gas. A fuel cell system comprising: a hydrogen pump capable of flowing a hydrogen gas having a lower water content than that of the gas to a movable part when the operation is stopped. 4. A fuel cell that is supplied with hydrogen gas and an oxidant gas to generate electricity, a hydrogen gas supply channel that supplies hydrogen gas to the fuel cell, and a hydrogen off gas discharged from the fuel cell. 3. A hydrogen off-gas circulation channel that returns to the hydrogen gas supply channel, and the hydrogen pump according to claim 2, which is arranged in any one of the hydrogen gas supply channel and the hydrogen off-gas circulation channel. Fuel cell system. 5. Exhaust means capable of discharging the gas flowing through the hydrogen off-gas circulation channel, and scavenging gas introducing means capable of introducing the hydrogen gas flowing through the hydrogen gas supply channel into a movable part of the hydrogen pump. And a scavenging control means for controlling the exhaust means and the scavenging gas introducing means to scavenging the inside of the hydrogen pump when the fuel cell is stopped. The fuel cell system described. 6. A shutoff valve disposed upstream and downstream of the hydrogen pump capable of shutting off gas flow into and out of the hydrogen pump; and a sealing control means for closing the shutoff valve after completion of scavenging of the hydrogen pump. The fuel cell system according to claim 5, wherein: