JP2023128014A - fuel cell system - Google Patents

Abstract

To suppress generation of water after drainage treatment in a fuel cell system executing the drainage treatment before a vehicle reaches a destination.SOLUTION: A fuel cell system is mounted in a vehicle. The fuel cell system includes: a fuel cell which supplies power to a travel motor of the vehicle; a discharge pipe which is connected to the fuel cell; a control section which executes drainage treatment for discharging water generated in the fuel cell from the discharge pipe; a secondary cell; and a navigation system. The control section executes the drainage treatment before the vehicle reaches a registration point when the vehicle is moving toward the registration point of the navigation system and travels the vehicle by power of the secondary cell in a state that power generation by the fuel cell is stopped after the completion of the drainage treatment.SELECTED DRAWING: Figure 2

Description

The technology disclosed herein relates to a fuel cell system.

The fuel cell system disclosed in Patent Document 1 is mounted on a vehicle and supplies electric power to the vehicle's driving motor. Since fuel cells generate electricity by reacting hydrogen gas and oxidizing gas, water is generated inside the fuel cell. This fuel cell system has a control section. The control unit controls each part of the fuel cell system to perform wastewater treatment in which water produced in the fuel cell is discharged from the discharge pipe. By discharging the generated water from the fuel cell through wastewater treatment, it is possible to prevent abnormalities caused by the generated water (for example, freezing of the generated water, etc.) within the fuel cell.

Furthermore, if wastewater treatment is carried out while the vehicle is parked at home or the like, the generated water may be repeatedly discharged to the same location, which may pose a problem. Furthermore, if wastewater treatment is carried out while the vehicle is stopped in a multi-story parking lot, the generated water may splash onto the equipment underneath the vehicle and other vehicles, which may pose a problem. In order to solve such problems, the fuel cell system disclosed in Patent Document 1 uses a navigation system to detect the position of the vehicle, and a control unit carries out wastewater treatment before the vehicle arrives at its destination. do. This prevents generated water from being discharged at the destination.

JP2021-082485A

In the fuel cell system disclosed in Patent Document 1, after wastewater treatment is completed, the fuel cell generates electricity to drive the vehicle, so water is generated within the fuel cell again. Therefore, produced water is present within the fuel cell upon arrival at the destination. Therefore, if the vehicle is stopped as it is, there is a risk that an abnormality will occur in the fuel cell due to the generated water. Furthermore, if wastewater treatment is carried out after the vehicle has stopped, water will be discharged at the destination. This specification proposes a technology for suppressing the generation of water after wastewater treatment in a fuel cell system that performs wastewater treatment before a vehicle arrives at its destination.

The fuel cell system disclosed in this specification is mounted on a vehicle. This fuel cell system includes a fuel cell that supplies power to a driving motor of the vehicle, a discharge pipe connected to the fuel cell, and a wastewater treatment system that discharges water generated within the fuel cell from the discharge pipe. It has a control unit that performs this, a secondary battery, and a navigation system. When the vehicle is moving toward a registered point in the navigation system, the control unit performs the wastewater treatment before the vehicle arrives at the registered point, and performs the fuel treatment after the wastewater treatment is completed. The vehicle is driven by the power of the secondary battery while power generation by the battery is stopped.

In this fuel cell system, the control unit carries out wastewater treatment before the vehicle arrives at the registration point. Further, after the wastewater treatment is completed, the control unit causes the vehicle to run using the electric power of the secondary battery while stopping power generation by the fuel cell. Therefore, generation of water within the fuel cell can be suppressed from the time the wastewater treatment is completed until the vehicle arrives at the registration point.

1 is a block diagram of a fuel cell system 10. FIG. Flowchart of position control wastewater treatment.

A fuel cell system 10 according to the embodiment shown in FIG. 1 is mounted on a vehicle. The vehicle has a motor 70. The motor 70 is a motor for driving the vehicle. The motor 70 uses the electric power generated by the fuel cell system 10 to rotate the drive wheels of the vehicle.

The fuel cell system 10 includes a fuel cell 20, an oxidizing gas circuit 30, a hydrogen gas circuit 40, and a secondary battery 72. The fuel cell system 10 has an oxidizing gas flow path 22 and a hydrogen gas flow path 24 inside. The oxidizing gas circuit 30 supplies oxidizing gas to the oxidizing gas passage 22 of the fuel cell 20 . The hydrogen gas circuit 40 supplies hydrogen gas to the hydrogen gas flow path 24 of the fuel cell 20 . The fuel cell 20 generates electricity by causing the oxidizing gas in the oxidizing gas flow path 22 and the hydrogen gas in the hydrogen gas flow path 24 to react. Fuel cell 20 is electrically connected to motor 70 and secondary battery 72. The connection state between the fuel cell 20, motor 70, and secondary battery 72 can be changed using a switch (not shown) or the like. When electric power is supplied from the fuel cell 20 to the motor 70, the motor 70 is activated. When power is supplied from the fuel cell 20 to the secondary battery 72, the secondary battery 72 is charged. Further, the motor 70 can also be operated by receiving power from the secondary battery 72.

The fuel cell system 10 includes a control section 60. The control unit 60 is composed of an arithmetic circuit including a processor, memory, and the like. The control unit 60 is electrically connected to each part of the fuel cell system 10 and controls them. Further, the control unit 60 changes the connection state between the fuel cell 20, the motor 70, and the secondary battery 72 by controlling a switch (not shown) or the like.

As described above, the oxidizing gas circuit 30 supplies oxidizing gas to the fuel cell 20. In this embodiment, the oxidizing gas is air. The oxidizing gas circuit 30 includes an oxidizing gas supply pipe 32 and an oxidizing gas exhaust pipe 33.

An intake port 32a is provided at the upstream end of the oxidizing gas supply pipe 32 to suck air from outside the vehicle. The downstream end of the oxidizing gas supply pipe 32 is connected to the upstream end of the oxidizing gas passage 22 of the fuel cell 20 . The oxidizing gas supply pipe 32 is provided with an air compressor 36 and a control valve 38. The control valve 38 is installed downstream of the air compressor 36. The air compressor 36 compresses the air in the oxidizing gas supply pipe 32 and sends it downstream. The control valve 38 opens and closes the oxidizing gas supply pipe 32 and adjusts the degree of opening of the oxidizing gas supply pipe 32. The air compressor 36 and the control valve 38 are connected to and controlled by the control section 60. The control unit 60 controls the flow rate of air supplied from the oxidizing gas supply pipe 32 to the oxidizing gas passage 22 by adjusting the output of the air compressor 36 and the opening degree of the control valve 38.

The upstream end of the oxidizing gas exhaust pipe 33 is connected to the downstream end of the oxidizing gas flow path 22 of the fuel cell 20 . An oxidizing gas exhaust port 33a is formed at the downstream end of the oxidizing gas exhaust pipe 33 to exhaust air to the outside of the vehicle. The oxidizing gas exhaust pipe 33 is provided with a control valve 39 . The control valve 39 opens and closes the oxidizing gas exhaust pipe 33 and adjusts the degree of opening of the oxidizing gas exhaust pipe 33 . The control valve 39 is connected to and controlled by the control section 60. The control unit 60 controls the flow rate of air flowing from the oxidizing gas flow path 22 to the oxidizing gas exhaust pipe 33 by adjusting the opening degree of the control valve 39 .

The hydrogen gas circuit 40 has a hydrogen gas supply pipe 42, a hydrogen gas discharge pipe 43, and a reflux pipe 50.

A hydrogen gas supply source 44 is connected to the upstream end of the hydrogen gas supply pipe 42 . The hydrogen gas supply source 44 is configured by, for example, a hydrogen gas tank. The hydrogen gas supply source 44 supplies high pressure hydrogen gas to the hydrogen gas supply pipe 42 . The downstream end of the hydrogen gas supply pipe 42 is connected to the upstream end of the hydrogen gas flow path 24 of the fuel cell 20. The hydrogen gas supply pipe 42 is provided with an on-off valve 45, a control valve 46, and an injector 47. The control valve 46 is installed downstream of the on-off valve 45, and the injector 47 is installed downstream of the control valve 46. The on-off valve 45 opens and closes the hydrogen gas supply pipe 42 . The control valve 46 opens and closes the hydrogen gas supply pipe 42 and adjusts the degree of opening of the hydrogen gas supply pipe 42 . The injector 47 injects hydrogen gas downstream. A reflux pipe 50 is connected to the hydrogen gas supply pipe 42 on the downstream side of the injector 47 . Hydrogen gas (so-called off-gas) after passing through the fuel cell 20 is supplied from the reflux pipe 50 to the hydrogen gas supply pipe 42 . Therefore, hydrogen gas and off-gas supplied from the hydrogen gas supply source 44 are supplied from the hydrogen gas supply pipe 42 to the hydrogen gas passage 24 of the fuel cell 20 . The on-off valve 45 and the control valve 46 are connected to and controlled by the control section 60. The control unit 60 controls the flow rate of hydrogen gas supplied from the hydrogen gas supply pipe 42 to the hydrogen gas passage 24 by adjusting the opening degree of the control valve 46 .

The hydrogen gas exhaust pipe 43 has an upstream section 43x and a downstream section 43y. The upstream end of the upstream section 43x is connected to the downstream end of the hydrogen gas flow path 24 of the fuel cell 20. A downstream end of the upstream section 43x is connected to a gas-liquid separator 48. The upstream end of the downstream section 43y is connected to the gas-liquid separator 48. A hydrogen gas discharge port 43a for discharging hydrogen gas to the outside of the vehicle is formed at the downstream end of the downstream portion 43y. A control valve 51 is provided at the downstream portion 43y of the hydrogen gas exhaust pipe 43. The control valve 51 opens and closes the downstream section 43y and adjusts the opening degree of the downstream section 43y. The upstream end of the reflux pipe 50 is connected to the gas-liquid separator 48 . A downstream end of the reflux pipe 50 is connected to a portion of the hydrogen gas supply pipe 42 on the downstream side of the injector 47 . A reflux pump 49 is provided in the reflux pipe 50 . The reflux pump 49 sends out the hydrogen gas in the reflux pipe 50 to the downstream side. Hydrogen gas (that is, off-gas) discharged from the hydrogen gas flow path 24 of the fuel cell 20 flows into the gas-liquid separation device 48 through the upstream section 43x. The gas-liquid separator 48 removes moisture from the hydrogen gas. The gas-liquid separator 48 supplies hydrogen gas from which moisture has been removed to the reflux pipe 50, and discharges moisture and excess hydrogen gas to the downstream section 43y. As described above, the hydrogen gas in the reflux pipe 50 is supplied to the hydrogen gas supply pipe 42 by the reflux pump 49. Moisture and hydrogen gas in the downstream portion 43y are discharged to the outside of the vehicle from the hydrogen gas discharge port 43a. The control valve 51 and the reflux pump 49 are connected to and controlled by the control section 60. The control unit 60 controls the flow rate of hydrogen gas discharged from the downstream portion 43y to the outside of the vehicle by adjusting the opening degree of the control valve 51.

The fuel cell system 10 includes a navigation system 62. The navigation system 62 is a general navigation system that specifies the current position of the vehicle using GPS and displays it on a map. Furthermore, the navigation system 62 calculates a driving route from the current position of the vehicle to the destination and displays it on a map. The control unit 60 can control the fuel cell system 10 in cooperation with the navigation system 62.

Next, the general operation of the fuel cell system 10 when the vehicle is running will be described. When the vehicle is running, the control unit 60 opens the control valves 38 and 39 and operates the air compressor 36. As a result, air flows from the oxidizing gas supply pipe 32 through the oxidizing gas passage 22 to the oxidizing gas exhaust pipe 33. Further, the control unit 60 opens the on-off valve 45 and the control valves 46 and 51, and operates the reflux pump 49. As a result, hydrogen gas flows from the hydrogen gas supply pipe 42 to the hydrogen gas discharge pipe 43 through the hydrogen gas passage 24 . Inside the fuel cell 20, the air flowing in the oxidizing gas flow path 22 and the hydrogen gas flowing in the hydrogen gas flow path 24 react to generate electric power. The control unit 60 causes the vehicle to travel by supplying power from the fuel cell 20 to the motor 70. Further, while the vehicle is running, the control unit 60 can charge the secondary battery 72 by supplying power from the fuel cell 20 to the secondary battery 72. Further, when the motor 70 is regenerating, the control unit 60 can charge the secondary battery 72 by supplying the electric power generated by the motor 70 to the secondary battery 72.

Next, wastewater treatment of the fuel cell system 10 will be explained. As described above, air and hydrogen gas react within the fuel cell 20 while the vehicle is running. Therefore, water is generated within the fuel cell 20 while the vehicle is running. In the fuel cell 20, produced water is mainly generated within the oxidizing gas flow path 22. The control unit 60 can perform a discharge process to discharge the generated water in the oxidizing gas flow path 22. Wastewater treatment can be carried out either while the vehicle is running or while the vehicle is stopped. In the discharge process, the control unit 60 operates the air compressor 36 at a higher output than in the general operation described above. Then, high-pressure air flows into the oxidizing gas flow path 22, and the generated water in the oxidizing gas flow path 22 is flowed together with the air. The generated water in the oxidizing gas flow path 22 is flowed together with air into the oxidizing gas exhaust pipe 33, and is discharged to the outside of the vehicle from the oxidizing gas exhaust port 33a. As a result, the generated water in the oxidizing gas flow path 22 is removed.

Next, a description will be given of position-controlled wastewater treatment in which wastewater treatment is performed using vehicle position information. In the position-controlled wastewater treatment, the control unit 60 and the navigation system 62 cooperate to cause the fuel cell system 10 to perform the process shown in FIG. 2. In step S2, the user of the vehicle operates the navigation system 62 to set the destination G. Then, the navigation system 62 sets a travel route from the current location of the vehicle to the destination G. Next, in step S4, the navigation system 62 sets a point at a distance L1 from the destination G on the travel route as the scheduled drainage execution point A. At the same time, the navigation system 62 sets a point at a distance L2 from the destination G on the driving route as the power remaining amount adjustment execution point B. The distance L2 is longer than the distance L1. That is, the power remaining amount adjustment execution point B is set at a position farther from the destination G than the drainage execution scheduled point A. Thereafter, the vehicle starts running according to the driver's operation. After the start of running, the control unit 60 causes the vehicle to run according to the general operation described above.

While the vehicle is traveling, the navigation system 62 determines whether the vehicle has passed through the power remaining amount adjustment execution point B in step S6. If NO in step S6, the navigation system 62 determines whether the destination G has been reached in step S22. If the determination in step S6 is NO, the determination in step S22 is also NO. Therefore, until the vehicle reaches the power remaining amount adjustment execution point B, the determinations in steps S6 and S22 are repeatedly performed. Therefore, until the vehicle passes through the power remaining amount adjustment execution point B, the control unit 60 continues the general operation without performing any special processing.

When the vehicle passes through the power remaining amount adjustment execution point B, the navigation system 62 determines YES in step S6. Then, the navigation system 62 determines whether the vehicle has passed through the scheduled drainage execution point A in step S8. In the case of NO in step S8, the control unit 60 calculates the estimated energy value Emot required to travel from the scheduled drainage execution point A to the destination G in step S10. The estimated energy value Emot can be calculated based on the distance from the current location of the vehicle to the destination G and the latest or past average fuel consumption. Next, in step S12, the control unit 60 determines whether the remaining amount Ebat of the secondary battery 72 is lower than the estimated energy value Emot. The control unit 60 executes step S14 when the remaining amount Ebat of the secondary battery 72 is lower than the estimated energy value Emot, and executes step S14 when the remaining amount Ebat of the secondary battery 72 is greater than or equal to the estimated energy value Emot. Skip. In step S14, the control unit 60 performs secondary battery charging control. That is, the control unit 60 increases the remaining amount Ebat of the secondary battery 72 by supplying power from the fuel cell 20 to the secondary battery 72 at an appropriate timing while the vehicle is running. After performing step S14, the navigation system 62 determines whether the destination G has been reached in step S22. In the case of NO in step S8, the determination in step S22 is also NO. Therefore, steps S6, S8, S10, S12, S14, and S22 are repeatedly performed from the time the vehicle passes through the power remaining amount adjustment execution point B until the vehicle reaches the scheduled drainage execution point A. Therefore, during this time, the secondary battery 72 is charged so that the remaining amount Ebat of the secondary battery 72 exceeds the estimated energy value Emot. Further, if the remaining amount Ebat of the secondary battery 72 exceeds the estimated energy value Emot, step S14 is skipped, so that the remaining amount Ebat of the secondary battery 72 is maintained at a value exceeding the estimated energy value Emot. .

When the vehicle passes through the scheduled drainage execution point A, the navigation system 62 determines YES in step S8. Then, in step S16, the control unit 60 determines whether or not wastewater treatment has been completed. In the first step S16, the control unit 60 determines NO because the waste water treatment has not been performed yet. Therefore, the control unit 60 carries out wastewater treatment in step S18. Through the wastewater treatment, generated water is discharged from the oxidizing gas flow path 22 of the fuel cell 20 to the outside of the vehicle. In this way, wastewater treatment is performed before arriving at destination G.

When the wastewater treatment is completed, the control unit 60 performs secondary battery running in step S20. In the secondary battery driving mode, the control unit 60 stops power generation by the fuel cell 20 and operates the motor 70 by supplying electric power from the secondary battery 72 to the motor 70 . Note that the control unit 60 stops the power generation by the fuel cell 20 by stopping the air compressor 36, stopping the reflux pump 49, and closing the valves 38, 39, 45, 46, and 51. After performing step S20, the navigation system 62 determines whether the destination G has been reached in step S22. If the destination G has not been reached, NO is determined in step S22. Therefore, from the time the waste water treatment is completed until the vehicle reaches the destination G, steps S6, S8, S16, and S20 are repeatedly performed. That is, from the time the waste water treatment is completed until the vehicle reaches the destination G, the secondary battery driving continues. Note that since the determination in step S16 from the second time onwards is YES, step S18 is skipped. Thereafter, when the vehicle arrives at the destination G by running on the secondary battery, YES is determined in step S22, and the process of FIG. 2 ends.

As described above, in the position-controlled wastewater treatment, the fuel cell system 10 performs the wastewater treatment at the scheduled drainage execution point A before the vehicle arrives at the destination G. Further, after the wastewater treatment is completed, the fuel cell system 10 causes the vehicle to run using the secondary battery. Before traveling on the secondary battery, the secondary battery is charged so that the remaining amount Ebat of the secondary battery 72 exceeds the estimated energy value Emot, so the vehicle travels from the scheduled drainage execution point A to the destination G using the secondary battery traveling. be able to. Furthermore, since the fuel cell 20 does not generate electricity after wastewater treatment, water is not generated within the fuel cell 20. Therefore, when the vehicle arrives at destination G, almost no produced water is present in the fuel cell 20. Therefore, even if the wastewater treatment is not performed after arriving at the destination G, it is possible to suppress the occurrence of an abnormality inside the fuel cell 20.

Note that in the above embodiment, the vehicle traveled the entire distance from the location where the wastewater treatment was performed to the destination using only the secondary battery. However, the fuel cell 20 may generate power in a part of the section from the location where the wastewater treatment is performed to the destination, and the generated power may be supplied to the motor 70 to drive the vehicle. For example, if the required power corresponding to the drive torque request of the motor 70 exceeds the upper limit of supply of the secondary battery 72, the fuel cell 20 may supply power to the motor 70. Even with this configuration, the amount of power generated by the fuel cell 20 after wastewater treatment can be reduced, so it is possible to reduce the amount of water generated within the fuel cell 20 after wastewater treatment than in the past.

Note that when running on a secondary battery, the motor 70 may be operated in a low power consumption mode (eg, eco mode, etc.). For example, by making the drive torque request for the motor 70 smaller than normal in relation to the amount of accelerator operation, the power required for the motor 70 is less likely to exceed the upper limit of the supply of the secondary battery 72 while suppressing the driver's discomfort. can do. Thereby, the operation of the fuel cell 20 can be suppressed after wastewater treatment.

Further, when the vehicle is used in a cold region, generated water is likely to freeze inside the fuel cell 20. Therefore, in such a case, after the vehicle arrives at the destination, more powerful wastewater treatment (for example, the air compressor 36 is operated with a higher output than normal wastewater treatment) while the fuel cell 20 is stopped. In some cases, wastewater treatment (e.g., wastewater treatment operated by In this case, since the wastewater treatment is carried out before arriving at the destination, the amount of generated water discharged from the wastewater treatment at the destination is very small. However, in order to reduce the amount of generated water discharged at the destination, in cold regions, wastewater treatment may be performed more intensively before arriving at the destination.

Furthermore, as mentioned above, in cold regions, strong wastewater treatment may be required after arriving at the destination. This waste water treatment is carried out with the fuel cell 20 stopped, so it is carried out using the electric power of the secondary battery 72. Furthermore, in cold regions, since it takes time to start up the fuel cell system the next time the vehicle is started, the vehicle may be forced to run on the secondary battery immediately after starting up. As described above, in cold regions, the amount of power used by the secondary battery 72 tends to increase after arriving at the destination. Therefore, when the vehicle is used in a cold region, the estimated energy value Emot and the scheduled drainage execution point A are set in position-controlled drainage processing so that the remaining capacity of the secondary battery 72 is higher upon arrival at the destination. You may.

Further, in the position-controlled drainage processing of the embodiment described above, a scheduled drainage execution point A is set, an estimated energy value Emot required for traveling from the drainage execution scheduled point A to a destination G is calculated, and then two The secondary battery 72 was charged so that the remaining amount Ebat of the secondary battery 72 was higher than the estimated energy value Emot. However, without setting the scheduled drainage execution point A, the control unit 60 checks the distance to the destination G and the remaining amount Ebat from time to time while the vehicle is running, and the energy required to travel to the destination G is checked. The waste water treatment may be executed at the timing when the amount becomes less than the amount Ebat. Even with this configuration, after wastewater treatment, the vehicle can travel to the destination G using the secondary battery.

Further, the fuel cell system 10 of the embodiment described above performs position control wastewater treatment when a destination is set by the navigation system 62. However, the fuel cell system 10 performs location-controlled wastewater treatment only when the user registers a specific point (for example, his home where he frequently stops) in the navigation system 62, and the registered point is set as the destination. Good too. Furthermore, even if the destination is not set in the navigation system 62, the navigation system 62 and the control unit 60 can autonomously determine that the vehicle is traveling toward a registered point (for example, home, etc.) and locate the destination. Controlled wastewater treatment may also be implemented.

Although the embodiments have been described in detail above, these are merely examples and do not limit the scope of the claims. The techniques described in the claims include various modifications and changes to the specific examples illustrated above. The technical elements described in this specification or the drawings exhibit technical usefulness singly or in various combinations, and are not limited to the combinations described in the claims as filed. Furthermore, the techniques illustrated in this specification or the drawings simultaneously achieve multiple objectives, and achieving one of the objectives has technical utility in itself.

10: Fuel cell system, 20: Fuel cell, 22: Oxidizing gas flow path, 24: Hydrogen gas flow path, 32: Oxidizing gas supply pipe, 33: Oxidizing gas exhaust pipe, 36: Air compressor, 42: Hydrogen gas supply pipe , 43: Hydrogen gas exhaust pipe, 60: Control unit, 62: Navigation system, 70: Motor, 72: Secondary battery

Claims (1)

A fuel cell system installed in a vehicle,
a fuel cell that supplies power to a driving motor of the vehicle;
an exhaust pipe connected to the fuel cell;
a control unit that performs wastewater treatment to discharge water generated within the fuel cell from the discharge pipe;
A secondary battery,
navigation system,
has
When the vehicle is moving toward a registered point in the navigation system, the control unit performs the wastewater treatment before the vehicle arrives at the registered point, and controls the fuel after the wastewater treatment is completed. driving the vehicle using electric power from the secondary battery while stopping power generation by the battery;
Fuel cell vehicle.

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