JP5152616B2 - Fuel cell system and method for stopping operation - Google Patents

Description

  The present invention relates to a fuel cell system in which an injector is provided in a gas supply system of a fuel cell, and an operation stop method thereof.

  Currently, a fuel cell system including a fuel cell that receives a supply of reaction gas (fuel gas and oxidizing gas) and generates electric power has been proposed and put into practical use. Such a fuel cell system is provided with a fuel supply channel for flowing fuel gas supplied from a fuel supply source such as a hydrogen tank to the fuel cell.

By the way, when the supply pressure of the fuel gas from the fuel supply source is extremely high, a pressure regulating valve (regulator) for reducing the supply pressure to a constant value is generally provided in the fuel supply passage. In recent years, the supply pressure of the fuel gas can be changed according to the operating state of the system by providing a fuel-modulating pressure valve (variable regulator) that changes the supply pressure of the fuel gas, for example, in two stages. The technique to make is proposed (for example, refer patent document 1).
JP 2004-139984 A

  However, the conventional mechanical adjustable pressure valve as described in Patent Document 1 is difficult to change the supply pressure of the fuel gas quickly (that is, the response is low) due to its structure. In addition, it is impossible to perform high-precision pressure adjustment that changes the target pressure in multiple stages.

  In addition, since the conventional mechanically adjustable pressure valve has a relatively complicated configuration, it is large, heavy and expensive to manufacture. Furthermore, since the conventional mechanically adjustable pressure valve simply changes the supply pressure of the fuel gas, it is necessary to separately provide a cutoff valve for cutting off the supply of the fuel gas. For this reason, there exists a problem of causing the enlargement of a system (increase of installation space) and the increase in equipment cost.

  Therefore, there is a demand for a fuel cell system with high responsiveness that can appropriately change the supply pressure of the fuel gas in accordance with the operating state of the fuel cell. As the water generated on the oxidant gas supply system passes through the fuel cell and mixes with the power generation, if the water remaining in the pressure regulating valve freezes, the stable operation of the pressure regulating valve at low temperature startup is hindered. Is done.

  The present invention has been made in view of such circumstances, and has a responsiveness that operates stably even at low temperature startup and can appropriately change the supply pressure of the fuel gas in accordance with the operating state of the fuel cell. It is an object of the present invention to provide a high fuel cell system and a method for stopping the fuel cell system.

  In order to achieve the above object, a fuel cell system according to the present invention includes a fuel cell, a gas supply system for supplying a reaction gas to the fuel cell, and a gas state on the upstream side of the gas supply system by adjusting a downstream gas state. In the fuel cell system, the injector is provided with an internal channel that communicates the upstream side and the downstream side, and is movably disposed in the internal channel and opens and closes the channel. A valve body that changes the state, and includes a moisture reducing means that reduces at least moisture around the valve body of the injector when the system is stopped or after the system is stopped.

  According to such a configuration, the injector can be operated in accordance with the operating state of the fuel cell (power generation amount (power, current, voltage) of the fuel cell, temperature of the fuel cell, abnormal state of the fuel cell system, abnormal state of the fuel cell body, etc.). The operating state (opening of the injector valve element (gas passage area), opening time of the injector valve element (gas injection time), etc.) can be set. Therefore, the supply pressure of the fuel gas can be appropriately changed according to the operating state of the fuel cell, and the responsiveness can be improved. The “gas state” means a gas state (flow rate, pressure, temperature, molar concentration, etc.), and particularly includes at least one of a gas flow rate and a gas pressure.

  In addition, since the moisture reducing means reduces the moisture around the valve body, which is a movable part in the injector, when the system is stopped, even if the fuel cell system is exposed to a low temperature environment, the moisture is frozen in the injector. The sticking of the valve body is suppressed.

  The injector includes a valve body drive unit (for example, a solenoid) that drives the valve body by energization, and the moisture reducing unit reduces moisture around the valve body by energization control to the valve body drive unit. It may be a thing.

  According to such a configuration, since the temperature of the reaction gas is raised by the heat generated by the valve body drive unit due to energization, the water vaporized at least partially around the valve body due to the temperature rise is easily discharged out of the injector. Further, since the reaction gas is used as the temperature rising gas, it is not necessary to add a new piping system or the like to supply the temperature rising gas.

  The moisture reducing means may be a unit that opens the injector after energizing a current that keeps the valve closed in the valve body drive unit of the injector to raise the temperature of the reaction gas.

  According to such a configuration, it is possible to perform a moisture reduction process with a smaller amount of gas by raising the temperature of the reaction gas by the valve body driving unit while the injector is in a closed state.

  In the fuel cell system of the present invention, the injector is disposed in a fuel gas supply system that communicates with the fuel electrode side of the fuel cell, and the moisture reducing means is configured to open the injector before opening the injector. The pressure on the fuel electrode side of the fuel cell may be lower than the target pressure after the system is stopped.

  According to such a configuration, the pressure on the fuel electrode side is reduced below a predetermined target pressure by, for example, generating power in the fuel cell in a state where the fuel supply is shut off, so that the inside of the injector disposed in the fuel gas supply system is reduced. It is possible to promote vaporization of moisture.

  The shut-off valve for shutting off the gas supply from the reaction gas supply source is provided upstream of the injector, and the moisture reducing means closes the shut-off valve and then the current required for opening the injector (so-called inrush current) ) Is continuously energized to the valve body drive unit, the shutoff valve is opened to supply the reaction gas from the reaction gas supply source to the injector, the injector is then closed, and the shutoff valve is closed. You may speak.

  According to this configuration, since the shutoff valve is closed, even if the injector is opened, no reaction gas is supplied to the injector. Moreover, the solenoid is continuously energized with a current necessary for opening the injector, that is, a current larger than a so-called valve-opening holding current. Therefore, the gas in the injector can be raised in a short time, and the water in the injector can be efficiently vaporized.

  When the shut-off valve is opened from this state, the temperature rising gas in the injector is pushed out of the injector together with the moisture vaporized at least partly by the reaction gas supplied from the upstream (reaction gas supply source) of the shut-off valve. Thereafter, the moisture reduction process is completed by closing the injector and closing the shutoff valve.

  The fuel cell system of the present invention comprises a circulation channel for returning the off-gas of the reaction gas discharged from the fuel cell to the fuel cell, and a pump disposed in the circulation channel, and the moisture reduction The means may perform a process of reducing moisture around the valve body when the rotational speed of the pump is equal to or lower than a predetermined rotational speed.

  According to such a configuration, it is possible to perform the moisture reduction process in a state where the rotational speed of the pump is sufficiently low and there is no water splash from the circulation flow path on the downstream side of the gas flow from the injector.

  The moisture reducing unit is configured to complete the generation of power by the fuel cell (for example, the generation of power for reaction gas consumption and the generation of pressure for depressurization of a gas supply system performed after receiving a system stop command). A process for reducing moisture around the valve body may be performed.

  According to such a configuration, the moisture reduction process is performed without the generation of water accompanying power generation and the supply of gas necessary for power generation, so that it is possible to suppress moisture from adhering to the valve body in the injector.

  The moisture reducing means, for example, as a dew condensation suppressing process which is one form of the moisture reducing process, energizes a current that maintains a closed state in the valve body drive unit of the injector for a predetermined time, and then stops the energization. But you can.

  According to such a configuration, a weak current smaller than the valve opening holding current flows through the valve body drive unit of the injector for a predetermined time, so that the valve body drive unit generates heat and the temperature of the injector rises. Therefore, the gas supply is faster than the injector. Condensation occurs in the system piping, and the occurrence of condensation in the injector is suppressed.

  The predetermined time may be set according to the outside air or the temperature of the fuel cell.

  According to such a configuration, it is possible to optimize the energization time of the valve closing holding current, and hence to shorten the time required for the system stop process including the condensation suppression process.

  The moisture reducing unit may intermittently energize the valve body driving unit of the injector after the system is stopped. On / off of the current during the intermittent energization is controlled by, for example, a timer.

  The moisture reducing means may be configured to energize the valve body drive unit of the injector when dew condensation is predicted to occur around the valve body of the injector.

  According to such a configuration, it is possible to omit the execution of the dew condensation suppressing process which is unnecessary when there is no risk of the occurrence of dew condensation. Even if there is a possibility of the occurrence of condensation, the occurrence of condensation can be suppressed.

  A fuel cell system shutdown method according to the present invention includes a fuel cell, a gas supply system for supplying a reaction gas to the fuel cell, and a gas state on the upstream side of the gas supply system to adjust the gas state downstream. A method of stopping operation of a fuel cell system including an injector to be supplied includes a step of reducing at least water around a valve element disposed in an internal flow path of the injector when the system is stopped.

  According to such a configuration, the moisture around the valve body, which is a movable part in the injector, is reduced when the system is stopped. Therefore, even if the fuel cell system is exposed to a low temperature environment, the valve is caused by the moisture being frozen in the injector. Sticking of the body is suppressed.

  According to the present invention, it is possible to reduce the moisture present around the injector valve body when the system is stopped. Therefore, it is possible to suppress malfunction due to freezing in the injector and to improve start-up reliability in a low-temperature environment. Can be made.

  Hereinafter, a fuel cell system 1 according to an embodiment of the present invention will be described with reference to the drawings. In the present embodiment, an example in which the present invention is applied to an on-vehicle power generation system of a fuel cell vehicle (moving body) will be described.

  First, the configuration of the fuel cell system 1 according to the embodiment of the present invention will be described with reference to FIG.

  As shown in FIG. 1, the fuel cell system 1 according to the present embodiment includes a fuel cell 10 that generates electric power upon receiving a supply of reaction gas (oxidation gas and fuel gas), and the fuel cell 10 has an oxidant gas. An oxidizing gas piping system 2 for supplying the air, a hydrogen gas piping system 3 for supplying hydrogen gas as a fuel gas to the fuel cell 10, a control device 4 for integrated control of the entire system, and the like.

  The fuel cell 10 has a stack structure in which a required number of unit cells that generate power upon receiving a reaction gas are stacked. The electric power generated by the fuel cell 10 is supplied to a PCU (Power Control Unit) 11. The PCU 11 includes an inverter, a DC-DC converter, and the like that are disposed between the fuel cell 10 and the traction motor 12. Further, the fuel cell 10 is provided with a current sensor 13 for detecting a current during power generation.

  The oxidant gas piping system 2 includes an air supply passage 21 that supplies the oxidant gas (air) humidified by the humidifier 20 to the fuel cell 10, and an air exhaust that guides the oxidant off-gas discharged from the fuel cell 10 to the humidifier 20. A flow path 22 and an exhaust flow path 23 for guiding the oxidizing off gas from the humidifier 20 to the outside are provided. The air supply passage 21 is provided with a compressor 24 that takes in the oxidizing gas in the atmosphere and pumps it to the humidifier 20.

  The hydrogen gas piping system 3 is used to supply a hydrogen tank 30 as a fuel supply source (reaction gas supply source) that stores high-pressure (for example, 70 MPa) hydrogen gas, and to supply the hydrogen gas in the hydrogen tank 30 to the fuel cell 10. A hydrogen supply flow path 31 as a fuel supply flow path and a circulation flow path 32 for returning the hydrogen off-gas (reactive gas off-gas) discharged from the fuel cell 10 to the hydrogen supply flow path 31 are provided. The hydrogen gas piping system 3 is an embodiment of the gas supply system in the present invention.

  Instead of the hydrogen tank 30, a reformer that generates a hydrogen-rich reformed gas from a hydrocarbon-based fuel, a high-pressure gas tank that stores the reformed gas generated by the reformer in a high-pressure state, and Can also be employed as a fuel supply source. A tank having a hydrogen storage alloy may be employed as a fuel supply source.

  The hydrogen supply flow path 31 is provided with a shutoff valve 33 that shuts off or allows the supply of hydrogen gas from the hydrogen tank 30, a regulator 34 that adjusts the pressure of the hydrogen gas, and an injector 35. A primary pressure sensor 41 and a temperature sensor 42 that detect the pressure and temperature of the hydrogen gas in the hydrogen supply flow path 31 are provided on the upstream side of the injector 35. Further, on the downstream side of the injector 35 and upstream of the junction between the hydrogen supply flow path 31 and the circulation flow path 32, a secondary side pressure sensor 43 that detects the pressure of the hydrogen gas in the hydrogen supply flow path 31. Is provided.

  The regulator 34 is a device that regulates the upstream pressure (primary pressure) to a preset secondary pressure. In the present embodiment, a mechanical pressure reducing valve that reduces the primary pressure is employed as the regulator 34. The mechanical pressure reducing valve has a structure in which a back pressure chamber and a pressure adjusting chamber are formed with a diaphragm therebetween, and the primary pressure is reduced to a predetermined pressure in the pressure adjusting chamber by the back pressure in the back pressure chamber. Thus, a publicly known configuration for the secondary pressure can be employed.

  In the present embodiment, as shown in FIG. 1, the upstream pressure of the injector 35 can be effectively reduced by arranging two regulators 34 on the upstream side of the injector 35. For this reason, the design freedom of the mechanical structure (a valve body, a housing, a flow path, a drive device, etc.) of the injector 35 can be increased.

  In addition, since the upstream pressure of the injector 35 can be reduced, it is possible to prevent the valve body 65 of the injector 35 from becoming difficult to move due to an increase in the differential pressure between the upstream pressure and the downstream pressure of the injector 35. can do. Accordingly, it is possible to widen the adjustable pressure width of the downstream pressure of the injector 35 and to suppress a decrease in responsiveness of the injector 35.

The injector 35 is an electromagnetic drive type capable of adjusting a gas state such as a gas flow rate and a gas pressure by driving the valve body 65 directly with an electromagnetic drive force at a predetermined drive cycle and separating it from the valve seat. Open / close valve. That is, the injector 35 directly opens and closes the valves (valve body and valve seat) with an electromagnetic driving force, and has a high responsiveness because its driving cycle can be controlled to a highly responsive region.

  FIG. 3 is a cross-sectional view showing an embodiment of the injector 35. The injector 35 constitutes a part of the hydrogen supply flow path (fuel supply system) 31 and is disposed on the hydrogen tank 30 side of the hydrogen supply flow path 31 in one of the ports 51 and supplies hydrogen in the other port 52. A metal cylinder 54 having an internal flow path 53 disposed on the fuel cell 10 side of the flow path 31 is formed. The cylinder 54 includes a first passage portion 56 connected to the mouth portion 51, and A second passage portion 57 having a diameter larger than that of the first passage portion 56, which is connected to the opposite side to the mouth portion 51 of the first passage portion 56, and a side opposite to the first passage portion 56 of the second passage portion 57. From the 3rd passage part 58 larger in diameter than the 2nd passage part 57 connected, and the 2nd passage part 57 and the 3rd passage part 58 connected to the opposite side to the 2nd passage part 57 of this 3rd passage part 58 Are formed with the fourth passage portion 59 having a small diameter, and these are used as the internal flow path. 3 is configured.

  The injector 35 is movably inserted into a valve seat 61 made of a sealing member provided so as to surround the opening portion of the fourth passage portion 59 on the third passage portion 58 side, and the second passage portion 57. A metal valve body 65 having an umbrella portion 63 having a diameter larger than that of the second passage portion 57 disposed in the cylindrical portion 62 and the third passage portion 58 and having a communication hole 64 formed obliquely in the umbrella portion 63; One end side is inserted into the cylindrical portion 62 of the valve body 65 and the other end side is locked by a stopper 66 formed in the first passage portion 56 so that the valve body 65 is brought into contact with the valve seat 61 and is internally The valve body 65 is moved by moving the spring 67 that blocks the flow path 53 and the valve body 65 against the urging force of the spring 67 until it contacts the stepped portion 68 on the second passage portion 57 side of the third passage portion 58. Is connected to the internal flow path 53 through the communication hole 64 while being separated from the valve seat 61. De has a (valve body driving section) 69, a.

  In the present embodiment, the valve element 65 of the injector 35 is driven by energization control to the solenoid 69 that is an electromagnetic drive device, and the internal flow path 53 is turned on and off by turning on and off the pulsed excitation current supplied to the solenoid 69. The opening time (valve opening time) or opening area can be switched between two stages, multistage, continuous (no stage), or linear. That is, there are at least a method of changing the valve opening time and a method of changing the opening area as a method for controlling the open / close state of the injector 35.

  The flow rate and pressure of the hydrogen gas are controlled with high accuracy by controlling the gas injection time and gas injection timing of the injector 35 by the control signal output from the control device 4.

  As described above, the injector 35 supplies at least one of the opening area (opening) and the opening time of the valve body 65 provided in the internal flow path 53 of the injector 35 in order to supply a gas flow rate required downstream thereof. By changing, the gas flow rate (or hydrogen molar concentration) supplied to the downstream side (fuel cell 10 side) is adjusted.

  Since the gas flow rate is adjusted by opening and closing the valve body 65 of the injector 35 and the gas pressure supplied downstream of the injector 35 is reduced from the gas pressure upstream of the injector 35, the injector 35 is controlled by a pressure regulating valve (pressure reducing valve, Regulator). Further, in the present embodiment, a variable pressure control valve capable of changing the pressure adjustment amount (pressure reduction amount) of the upstream gas pressure of the injector 35 so as to match the required pressure within a predetermined pressure range in accordance with the gas requirement. Can also be interpreted.

  In the present embodiment, as shown in FIG. 1, the injector 35 is disposed on the upstream side of the junction A <b> 1 between the hydrogen supply flow path 31 and the circulation flow path 32. Further, as shown by a broken line in FIG. 1, when a plurality of hydrogen tanks 30 are employed as the fuel supply source, the hydrogen gas supplied from each hydrogen tank 30 joins more than the part (hydrogen gas joining part A2). The injector 35 is arranged on the downstream side.

  A discharge flow path 38 is connected to the circulation flow path 32 via a gas-liquid separator 36 and an exhaust drain valve 37. The gas-liquid separator 36 collects moisture from the hydrogen off gas. The exhaust / drain valve 37 operates according to a command from the control device 4 to discharge (purge) the moisture collected by the gas-liquid separator 36 and the hydrogen off-gas containing impurities in the circulation flow path 32 to the outside. Is.

  In addition, the circulation channel 32 is provided with a hydrogen pump 39 that pressurizes the hydrogen off gas in the circulation channel 32 and sends it to the hydrogen supply channel 31 side. The hydrogen off-gas discharged through the exhaust / drain valve 37 and the discharge passage 38 is diluted by the diluter 40 and merges with the oxidizing off-gas in the exhaust passage 23.

  The control device 4 detects an operation amount of an acceleration operation device (accelerator or the like) provided in the vehicle, receives control information such as an acceleration request value (for example, a required power generation amount from a load device such as the traction motor 12), Control the operation of various devices in the system.

  In addition to the traction motor 12, the load device is an auxiliary device (for example, a compressor 24, a hydrogen pump 39, a cooling pump motor, or the like) necessary for operating the fuel cell 10, and various types of vehicles involved in traveling of the vehicle. It is a collective term for power consumption devices including actuators used in devices (transmissions, wheel control devices, steering devices, suspension devices, etc.), occupant space air conditioners (air conditioners), lighting, audio, and the like.

  The control device 4 is configured by a computer system (not shown). Such a computer system includes a CPU, ROM, RAM, HDD, input / output interface, display, and the like, and various control operations are realized by the CPU reading and executing various control programs recorded in the ROM. It is like that.

  Specifically, as shown in FIG. 2, the control device 4 is consumed by the fuel cell 10 based on the operating state of the fuel cell 10 (current value during power generation of the fuel cell 10 detected by the current sensor 13). The amount of hydrogen gas (hereinafter referred to as “hydrogen consumption”) is calculated (fuel consumption calculation function: B1). In the present embodiment, the hydrogen consumption is calculated and updated for each calculation cycle of the control device 4 using a specific calculation formula representing the relationship between the current value of the fuel cell 10 and the hydrogen consumption.

  Further, the control device 4 determines the target pressure value of hydrogen gas (to the fuel cell 10) at the downstream position of the injector 35 based on the operating state of the fuel cell 10 (current value at the time of power generation of the fuel cell 10 detected by the current sensor 13). Target gas supply pressure) (target pressure value calculation function: B2). In the present embodiment, a position (pressure) where the secondary pressure sensor 43 is arranged for each calculation cycle of the control device 4 using a specific map representing the relationship between the current value of the fuel cell 10 and the target pressure value. The target pressure value at the pressure adjustment position where adjustment is required is calculated and updated.

  Further, the control device 4 calculates the feedback correction flow rate based on the deviation between the calculated target pressure value and the detected pressure value at the downstream position (pressure adjustment position) of the injector 35 detected by the secondary pressure sensor 43 ( Feedback correction flow rate calculation function: B3). The feedback correction flow rate is a hydrogen gas flow rate (pressure difference reduction correction flow rate) added to the hydrogen consumption in order to reduce the deviation between the target pressure value and the detected pressure value. In the present embodiment, the feedback correction flow rate is calculated and updated every calculation cycle of the control device 4 using a target tracking control law such as PI control.

  Moreover, the control apparatus 4 calculates the feedforward correction | amendment flow volume corresponding to the deviation of the target pressure value calculated last time and the target pressure value calculated this time (feedforward correction | amendment flow volume calculation function: B4). The feedforward correction flow rate is a change in the hydrogen gas flow rate due to the change in the target pressure value (correction flow corresponding to the pressure difference). In the present embodiment, the feedforward correction flow rate is calculated and updated every calculation cycle of the control device 4 using a specific calculation formula representing the relationship between the deviation of the target pressure value and the feedforward correction flow rate. .

  Further, the control device 4 determines the static flow rate upstream of the injector 35 based on the gas state upstream of the injector 35 (hydrogen gas pressure detected by the primary pressure sensor 41 and hydrogen gas temperature detected by the temperature sensor 42). (Static flow rate calculation function: B5). In the present embodiment, the static flow rate is calculated for each calculation cycle of the control device 4 using a specific calculation formula representing the relationship between the pressure and temperature of the hydrogen gas upstream of the injector 35 and the static flow rate. We are going to update.

  Further, the control device 4 calculates the invalid injection time of the injector 35 based on the gas state upstream of the injector 35 (pressure and temperature of hydrogen gas) and the applied voltage (invalid injection time calculation function: B6). Here, the invalid injection time means the time required from when the injector 35 receives a control signal from the control device 4 until the actual injection is started. In the present embodiment, the invalid injection time is calculated for each calculation cycle of the control device 4 using a specific map representing the relationship between the pressure and temperature of the hydrogen gas upstream of the injector 35, the applied voltage, and the invalid injection time. I am going to update it.

  Further, the control device 4 calculates the injection flow rate of the injector 35 by adding the hydrogen consumption amount, the feedback correction flow rate, and the feedforward correction flow rate (injection flow rate calculation function: B7). Then, the control device 4 calculates the basic injection time of the injector 35 by multiplying the value obtained by dividing the injection flow rate of the injector 35 by the static flow rate by the drive cycle of the injector 35, and the basic injection time and the invalid injection time. Are added to calculate the total injection time of the injector 35 (total injection time calculation function: B8).

  Here, the drive cycle means a stepped (on / off) waveform cycle representing the open / close state of the injection hole of the injector 35. In the present embodiment, the drive period is set to a constant value by the control device 4.

  And the control apparatus 4 controls the gas injection time and gas injection timing of the injector 35 by outputting the control signal for implement | achieving the total injection time of the injector 35 computed through the above procedure, and fuel cell The flow rate and pressure of the hydrogen gas supplied to 10 are adjusted.

  During normal operation of the fuel cell system 1, hydrogen gas is supplied from the hydrogen tank 30 to the fuel electrode of the fuel cell 10 through the hydrogen supply channel 31, and the air that has been subjected to humidification adjustment passes through the air supply channel 21. Then, power is generated by being supplied to the oxidation electrode of the fuel cell 10. At this time, the power (required power) to be drawn from the fuel cell 10 is calculated by the control device 4, and hydrogen gas and air in an amount corresponding to the amount of power generation are supplied into the fuel cell 10. In the present embodiment, the pressure of hydrogen gas supplied to the fuel cell 10 during such normal operation is controlled with high accuracy.

  By the way, the injector 35 also serves as a valve that partitions the humidification side (fuel cell 10 side) and the dry side (hydrogen tank 30 side). Therefore, taking measures against freezing is started at a low temperature (for example, below freezing point). It is important to realize After the fuel cell system 1 is stopped in a state where the moisture in the injector 35 is not reduced, if the temperature becomes below freezing at the next system startup, the water may freeze and the valve body 65 may be fixed, resulting in malfunction.

  As a method of reducing the moisture in the injector 35, a method is conceivable in which hydrogen gas is circulated through the internal flow path while the valve body 65 of the injector 35 is opened, and the internal flow path is scavenged by this hydrogen gas. In this case, a large amount of hydrogen gas is supplied to the fuel cell 10, which causes a problem that fuel consumption deteriorates.

  Therefore, in the fuel cell system 1 of the present embodiment, a moisture reduction process (scavenging process) is performed to reduce the moisture in the injector 35 when the system is stopped so as to reduce the moisture in the injector 35 while suppressing a decrease in fuel consumption. . This moisture reduction process is controlled by the control device 4. That is, the control device 4 of the present embodiment is an embodiment of a moisture reducing unit that performs energization control of the injector 35, opening / closing control of the shutoff valve 33, and the like.

  During normal operation, the injector 35 is cooled by the hydrogen gas supplied from the hydrogen tank 30, but when the hydrogen gas flow is stopped, the hydrogen gas in the injector 35 is heated by the heat generated by the solenoid 69. Is done. Therefore, when the control device 4 receives a system stop command such as ignition OFF (when the system is stopped), the control device 4 energizes the solenoid 69 of the injector 35 with a valve closing holding current.

  When the solenoid 69 generates heat by energization, the hydrogen gas staying in the injector 35 is heated by the generated solenoid 69. As a result, at least part of the water present around the valve body 65 is vaporized. Next, the control device 4 releases the valve closing state to open the injector 35 and continuously energizes the solenoid 69 with a current maintaining the valve opening state to open the injector 35.

  Then, together with the hydrogen gas supplied from the hydrogen tank 30, the water partially vaporized by the heated hydrogen gas existing around the valve body 65 is discharged from the injector 35. Furthermore, since the temperature of the injector 35 containing the valve element 65 and the downstream piping thereof are increased by the heated hydrogen gas, the subsequent moisture condensation is also suppressed.

  As described above, according to the fuel cell system 1 of the present embodiment, it is possible to efficiently vaporize and reduce the water present around the valve body 65 with a small amount of hydrogen gas. That is, the moisture in the injector 35 can be reduced while suppressing a decrease in fuel consumption. Therefore, the malfunction of the injector 35 due to freezing at the next low temperature start can be suppressed, and the start-up reliability in a low temperature environment can be improved.

  Further, according to the fuel cell system 1 of the present embodiment, the operating state (injection time) of the injector 35 can be set according to the operating state (current value during power generation) of the fuel cell 10. Accordingly, the supply pressure of hydrogen gas can be appropriately changed according to the operating state of the fuel cell 10, and the responsiveness can be improved. In addition, since the injector 35 is employed as the hydrogen gas flow rate adjustment valve and the adjustable pressure control valve, high-precision pressure adjustment (adjustment of the hydrogen gas supply pressure to the fuel cell 10) is possible.

  That is, since the injector 35 can receive the control signal from the control device 4 according to the operating state of the fuel cell 10 and adjust the injection time and injection timing of the hydrogen gas, the conventional mechanical adjustable pressure valve The pressure adjustment can be performed more quickly and accurately. In addition, the injector 35 is smaller, lighter, and less expensive than a conventional mechanically adjustable pressure valve, so that the entire system can be reduced in size and cost.

  The above-described embodiment is an example for explaining the present invention, and the present invention is not limited to this. Various components can be appropriately designed without departing from the gist of the present invention. Moreover, you may apply combining suitably other embodiment mentioned later.

  For example, in the moisture reduction process, the control device 4 may perform control to reduce the pressure on the fuel electrode side before the injector 35 is opened. Specifically, the control device 4 lowers the pressure on the fuel electrode side after the injector 35 is closed, for example, by generating power to the fuel cell 10 in a state where the supply of hydrogen gas is shut off.

  That is, as shown in FIG. 4, the fuel cell 10 is caused to generate power in a state in which the supply of hydrogen gas is cut off so that the pressure is lower than the target pressure after the final system stop (symbol a). The pressure in the passage 31 is reduced (reference number b). During the pressure reduction process, the solenoid 69 is energized to the extent that the closed state of the injector 35 is maintained (not released) as described above, and the temperature of the hydrogen gas in the injector 35 is raised (reference c).

  Thereafter, when an inrush current necessary for opening the injector 35 is applied to the solenoid 69 as indicated by reference sign d, hydrogen gas from the hydrogen tank 30 flows into the injector 35 and exists around the valve body 65. As the moisture is blown off, the pressure on the fuel electrode side rises to the target pressure (symbol a) as indicated by the symbol e.

  As described above, according to the present embodiment, by reducing the pressure on the fuel electrode side of the fuel cell 10, the vaporization of moisture in the injector 35 disposed in the hydrogen supply channel 31 is promoted. Further, it becomes possible to control the target pressure after the system is finished with higher accuracy than in the case of using the exhaust / drain valve 37.

  That is, the pressure control by the exhaust / drain valve 37 is limited in accuracy because the control fluid is gas-liquid mixture. Further, since the control pressure is low, the valve diameter must be increased, which is disadvantageous for improving the response. On the other hand, according to the pressure control using the injector 35 as in the present embodiment, the pressure control to the target pressure after the system is stopped can be performed with high accuracy. Therefore, the amount of cross leak of hydrogen gas to the oxygen electrode side when the system is stopped is reduced, and fuel efficiency can be improved.

  Further, as a moisture reduction process, the control device 4 continuously energizes the solenoid 69 with an inrush current (inrush current> open valve holding current) necessary for opening the injector 35 after closing the shutoff valve 33, After the shutoff valve 33 is opened and hydrogen gas from the hydrogen tank 30 is supplied to the injector 35 by continuous energization, the injector 35 may be closed and the shutoff valve 33 may be closed.

  After the injector 35 is opened, it is a general energization control of the solenoid 69 to switch to a valve opening holding current that is smaller than the inrush current required for valve opening. Since the inrush current larger than the valve opening holding current is continuously supplied even after the valve is opened, the temperature of the hydrogen gas in the injector 35 is increased in a shorter time or the same temperature increase time. The temperature can be raised to a higher temperature, and a more efficient moisture reduction process is realized.

  In addition, the control device 4 may perform each of the above moisture reduction processes only when the rotation speed of the hydrogen pump 39 is equal to or less than a predetermined rotation speed. For example, when the piping distance between the hydrogen pump 39 and the injector 35 is short, the water bounced from the circulation flow path 32 may adhere to the valve body 65 of the injector 35 located on the upstream side. When the rotational speed of 39 is lowered, there is no water splash from the downstream side, and adhesion of moisture to the valve body 65 of the injector 35 can be suppressed.

  The control device 4 includes all power generation by the fuel cell 10 (for example, power generation for hydrogen gas consumption and power generation for decompression of the hydrogen gas piping system 3 performed after receiving a system stop command). You may make it perform the above-mentioned moisture reduction process after complete | finishing. According to such a configuration, the moisture reduction process is performed without the generation of water accompanying power generation and the supply of gas necessary for power generation. Therefore, it is even more effective that water adheres to the valve body 65 in the injector 35. Can be suppressed.

  By the way, the injector 35 has an extremely small heat capacity as compared with each pipe (hereinafter referred to as hydrogen pipe) of the hydrogen supply flow path 31 and the circulation flow path 33. Therefore, the temperature decrease gradient of the injector 35 after the system is stopped is Larger than that of system piping. That is, the injector 35 is easier to cool than the hydrogen-based piping, and after the system is stopped, condensation occurs before the hydrogen-based piping.

  Therefore, as shown in FIG. 5, the control device 4 closes the solenoid 69 of the injector 35 as a dew condensation suppressing process, which is one form of the moisture reduction process according to the present invention, when a system stop command such as an ignition OFF is received. A valve closing holding current for maintaining the valve state, in other words, a current smaller than the valve opening holding current during the normal operation may be applied for a predetermined time, and then the energization may be stopped.

  In such a case, a weak current smaller than the valve opening holding current is allowed to flow through the solenoid 69 of the injector 35 for a predetermined time, so that the solenoid 69 generates heat and the temperature of the injector 35 rises. As a result, condensation occurs and the occurrence of condensation in the injector 35 is suppressed. Thus, malfunction of the injector 35 due to freezing is suppressed even below freezing.

  The energization time (predetermined time) of the valve closing holding current may be a fixed time set in advance, or the outside air temperature or the temperature of the fuel cell 10 (or the refrigerant for controlling the temperature of the fuel cell 10). It may be a variable time arbitrarily set according to (temperature). In the latter case, it is possible to optimize the energization time of the valve-holding holding current, and thus to shorten the time required for the system stop process including the dew condensation suppression process.

  Further, the above dew condensation suppressing process may be executed after the system is stopped instead of or in addition to being executed when the system is stopped. When the dew condensation suppression process is executed after the system is stopped, for example, as shown in FIG. 6, the control device 4 intermittently energizes the solenoid 69 of the injector 35 with a valve closing holding current after the system stops. On / off of the current during the intermittent energization is controlled by, for example, a timer.

  Further, the control device 4 performs the above-described dew condensation suppressing process, that is, energization of the solenoid 69 of the injector 35 when the system is stopped or after the system is stopped when it is predicted that dew condensation will occur around the valve body of the injector 35. May be executed.

  In such a case, it is possible to omit the use of condensation suppression processing that is unnecessary when there is no risk of condensation. Even when there is a risk of occurrence, the occurrence of condensation can be suppressed.

  Here, the possibility of dew condensation in the injector 35 is, for example, the outside air temperature, the temperature of the injector 35, the temperature of the fuel cell 10, the temperature of the hydrogen piping, and the value of the current sensor provided in the drive driver of the injector 35. It is possible to make a determination using at least one parameter among the parameters typified by the resistance value of the injector 35 and the like obtained from the above.

  In the above embodiment, the example in which the circulation channel 32 is provided in the hydrogen gas piping system 3 of the fuel cell system 1 has been shown. For example, as shown in FIG. Can be directly connected to eliminate the circulation flow path 32. Further, instead of installing the hydrogen pump 39 in the circulation channel 32, an ejector may be installed.

  In each of the above embodiments, the fuel cell system according to the present invention is mounted on the fuel cell vehicle. However, the present invention is applied to various mobile bodies (robots, ships, airplanes, etc.) other than the fuel cell vehicle. Such a fuel cell system can also be mounted. Further, the fuel cell system according to the present invention may be applied to a stationary power generation system used as a power generation facility for a building (house, building, etc.).

1 is a configuration diagram of a fuel cell system according to an embodiment of the present invention. It is a control block diagram for demonstrating the control aspect of the control apparatus of the fuel cell system shown in FIG. It is a longitudinal cross-sectional view of the injector used for the fuel cell system shown in FIG. FIG. 6 is a diagram showing a relationship between an energization current to an injector and a pressure on a fuel electrode side in another embodiment of the fuel cell system shown in FIG. 1. FIG. 5 is a diagram showing a relationship between an energization current to an injector and a system start / stop signal in another embodiment of the fuel cell system shown in FIG. 1. FIG. 5 is a diagram showing a relationship between an energization current to an injector and an elapsed time after the system is stopped in another embodiment of the fuel cell system shown in FIG. 1. FIG. 3 is a configuration diagram showing still another embodiment of the fuel cell system shown in FIG. 1.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Fuel cell system, 3 ... Hydrogen gas piping system (gas supply system, fuel gas supply system), 4 ... Control apparatus (moisture reduction means), 10 ... Fuel cell, 30 ... Hydrogen tank (reaction gas supply source), 31 DESCRIPTION OF SYMBOLS ... Hydrogen supply flow path, 32 ... Circulation flow path, 33 ... Shut-off valve, 35 ... Injector, 39 ... Hydrogen pump (pump), 53 ... Internal flow path, 65 ... Valve body, 69 ... Solenoid (valve body drive part)

Claims (11)

In a fuel cell system comprising a fuel cell, a gas supply system for supplying a reaction gas to the fuel cell, and an injector for adjusting a gas state on the upstream side of the gas supply system and supplying the gas to the downstream side,
The injector is configured to drive an internal flow path that communicates between the upstream side and the downstream side, a valve body that is movably disposed in the internal flow path and changes the open / closed state of the flow path, and drives the valve body by energization. And a valve body drive unit that
Comprising a moisture reducing means for reducing at least moisture around the valve body of the injector by energization control to the valve body drive unit at the time of system stop or after system stop ;
The moisture reducer energizes the current closing state is held in the valve body driving portion of the injector, after the temperature of the said reaction gas, a fuel cell system that opening the injector. The injector is disposed in a fuel gas supply system communicating with the fuel electrode side of the fuel cell,
2. The fuel cell system according to claim 1, wherein the moisture reducing unit lowers the pressure on the fuel electrode side of the fuel cell to be lower than a target pressure after the system is stopped before opening the injector. 3. A fuel cell; a gas supply system for supplying a reaction gas to the fuel cell; an injector for adjusting a gas state upstream of the gas supply system and supplying the gas downstream; and a reaction gas upstream of the injector A shut-off valve for shutting off gas supply from a supply source, and the injector is disposed so as to communicate with the upstream side and the downstream side of the injector, and is movable in the internal channel and is opened and closed. A fuel cell system comprising: a valve body for changing a state;
Comprising a moisture reducing means for reducing moisture at least around the valve body of the injector when the system is stopped or after the system is stopped;
After the shut-off valve is closed, the moisture reducing means continuously energizes the valve body drive unit with a current necessary for opening the injector, and opens the shut-off valve to supply the reaction gas from the reaction gas supply source. the reaction gas after supplying to the injector, and closed the injector, fuel cell system that closes the shut-off valve. A circulation channel for returning the off gas of the reaction gas discharged from the fuel cell to the fuel cell, and a pump disposed in the circulation channel,
The fuel cell system according to any one of claims 1 to 3 , wherein the moisture reducing means performs a process of reducing moisture around the valve body when the rotational speed of the pump is equal to or lower than a predetermined rotational speed. The fuel cell system according to any one of claims 1 to 4 , wherein the moisture reducing unit performs a process of reducing moisture around the valve body after all the power generation by the fuel cell is completed. 2. The fuel cell system according to claim 1 , wherein the moisture reducing means energizes a current for maintaining a closed state in the valve body driving unit of the injector for a predetermined time, and then stops the energization. The fuel cell system according to claim 6 , wherein the predetermined time is set according to outside air or a temperature of the fuel cell. The fuel cell system according to claim 1 , wherein the moisture reducing unit intermittently energizes the valve body driving unit of the injector after the system is stopped. 2. The fuel cell system according to claim 1 , wherein the moisture reducing unit energizes the valve body drive unit of the injector when it is predicted that condensation occurs around the valve body of the injector. 3. Operation of a fuel cell system comprising a fuel cell, a gas supply system for supplying a reaction gas to the fuel cell, and an injector for adjusting a gas state on the upstream side of the gas supply system and supplying the gas state to the downstream side In stopping method,
A method of stopping operation of a fuel cell system comprising a step of energizing a current that maintains a closed state to the valve body drive unit of the injector when the system is stopped, raising the temperature of the reaction gas, and then opening the injector . A fuel cell; a gas supply system for supplying a reaction gas to the fuel cell; an injector for adjusting a gas state upstream of the gas supply system and supplying the gas downstream; and a reaction gas upstream of the injector In a method for stopping operation of a fuel cell system comprising a shutoff valve for shutting off gas supply from a supply source,
When the system is stopped, the shut-off valve is closed, and then a current necessary for opening the injector is continuously supplied to the valve body drive unit of the injector, the shut-off valve is opened, and the reactive gas supply source A method for stopping the operation of the fuel cell system comprising the steps of: supplying the reaction gas from the fuel cell to the injector, closing the injector, and closing the shutoff valve.

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