JP4998695B2 - Fuel cell system - Google Patents

Description

  The present invention relates to a fuel cell system in which a reaction gas supplied from a tank is adjusted to a predetermined flow rate and supplied to a fuel cell.

In recent years, a fuel cell vehicle using a fuel cell that generates power by an electrochemical reaction between a fuel gas and an oxidizing gas as an energy source has attracted attention. As a fuel cell system provided in this fuel cell vehicle or the like, there is known a system that detects the pressure of fuel gas in a tank by a pressure sensor and obtains the remaining amount of fuel gas in the tank based on the detection result. (For example, refer to Patent Document 1).
JP-A-2005-240854

  By the way, since the pressure of the fuel gas tank is high, a high pressure sensor capable of detecting a high pressure is used as the pressure sensor. However, the high pressure sensor has a large sensor range, so the accuracy is not so good. A detection error may occur in the remaining amount of fuel gas. Further, when an abnormality occurs in the high-pressure sensor, it is difficult to detect the remaining amount of fuel gas in the tank because there is no other remaining amount detecting means.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a fuel cell system capable of monitoring the remaining amount of fuel gas with high accuracy and high reliability.

  In order to achieve the above object, the fuel cell system of the present invention adjusts the reaction gas supplied from a tank in which the reaction gas is stored at a predetermined pressure higher than the normal pressure to a predetermined flow rate by a flow rate adjustment valve. A fuel cell system to be supplied to a battery, wherein the remaining amount of reaction gas in the tank is determined based on a pressure pulsation state detected by a first pressure sensor disposed downstream of the flow rate adjustment valve. Is provided with a monitoring unit for monitoring the above.

  According to the fuel cell system having this configuration, the reaction gas in the tank is measured using the first pressure sensor having a measurement range relatively lower than the pressure sensor for detecting the pressure in the tank (hereinafter referred to as a high pressure sensor). Since the remaining amount is monitored, the remaining amount can be favorably monitored with higher accuracy and higher reliability than the remaining amount monitoring by the high pressure sensor. Further, it is possible to dispense with a high-pressure sensor. In such a case, the system can be simplified and the cost can be reduced.

  Further, as the flow rate adjusting valve, an electromagnetically driven on-off valve that drives the valve body at a predetermined driving cycle by an electromagnetic driving force to be separated from the valve seat may be provided. A modulatable pressure regulator whose value is variable may be provided.

  The monitoring unit may determine that the reaction gas in the tank is less than a predetermined amount based on a state of pressure pulsation detected by the first pressure sensor. For example, when the pressure pulsation detected by the first pressure sensor decreases or when the change amount of the pressure pulsation detected by the first pressure sensor becomes a predetermined determination value or more, It is possible to determine that the reaction gas is less than a predetermined amount.

  The monitoring unit may set a criterion for determining the remaining amount of the reaction gas based on the pressure pulsation detected by the first pressure sensor according to the number of the tanks.

  When the second pressure sensor for detecting the pressure in the tank is provided, the monitoring unit is configured to detect a pressure pulsation detected by the first pressure sensor and a detection result of the second pressure sensor. Based on this, the remaining amount of the reaction gas in the tank may be monitored.

  According to such a configuration, since the monitoring of the remaining amount of the reaction gas by the first pressure sensor and the monitoring of the remaining amount based on the detection result of the high pressure sensor are performed in duplicate, the reliability of the monitoring of the remaining amount of the reaction gas is improved. be able to.

  The monitoring unit may monitor the remaining amount of the reaction gas in the tank based on the state of pressure pulsation detected by the first pressure sensor when the second pressure sensor is abnormal.

  According to such a configuration, even when the high-pressure sensor is abnormal, the remaining amount of the reaction gas can be monitored and the reliability thereof can be improved.

  When a plurality of the tanks are provided, the used tank may be switched to another tank when the remaining amount of the reaction gas in the used tank becomes less than a predetermined value.

  The fuel cell system according to the present invention is disposed downstream of the pressure regulating valve after regulating the reactive gas supplied from a tank in which the reactive gas is stored at a predetermined pressure higher than normal pressure by the pressure regulating valve. A fuel cell system that adjusts the flow rate to a predetermined flow rate by the flow rate control valve and supplies the fuel cell to a fuel cell, the monitoring unit monitoring a remaining amount of the reaction gas in the tank based on an opening state of the pressure regulating valve; It may be provided.

  In this case, the monitoring unit may determine that the reaction gas in the tank is less than a predetermined value when the pressure regulating valve is fully opened.

  When the remaining amount of reaction gas in the tank decreases and the internal pressure falls below the set pressure of the pressure regulating valve, the opening state of the pressure regulating valve is fully opened. It includes a partial space. As a result, the width of the pressure pulsation caused by the opening and closing movement of the valve body in the pressure regulating valve is suddenly reduced, so that the monitoring unit can monitor the remaining amount of the reaction gas in the tank based on the change in the pressure pulsation.

  According to the fuel cell system of the present invention, the remaining amount of the reaction gas can be monitored with high accuracy and good.

  Hereinafter, a fuel cell system 1 according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a system configuration diagram of the fuel cell system 1. The fuel cell system 1 is used as an in-vehicle power generation system for fuel cell vehicles, a power generation system for any moving body such as a ship, an aircraft, a train, or a walking robot, and also as a power generation facility for buildings (housing, buildings, etc.). Although it can be applied to stationary power generation systems, it is specifically for automobiles.

  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 as a gas flow path for supplying air, a hydrogen gas piping system 3 as a gas flow path for supplying hydrogen gas as a fuel gas to the fuel cell 10, and a control device (monitoring) for integrated control of the entire system Part) 4 etc.

  The fuel cell 10 has a stack structure in which a required number of unit cells that receive a reaction gas and generate electric power through an electrochemical reaction are stacked. Here, the unit cell is of a solid polymer type, and is composed of an electrolyte membrane and a MEA (Membrane Electrode Assembly) composed of a pair of electrodes disposed on both surfaces thereof, and a pair of separators sandwiching the MEA. 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 (tank) 30 as a fuel supply source storing hydrogen gas at a pressure higher than normal pressure (for example, 70 MPa), and to supply the hydrogen gas in the hydrogen tank 30 to the fuel cell 10. A hydrogen supply channel 31 as a fuel supply channel and a circulation channel 32 for returning the hydrogen off-gas discharged from the fuel cell 10 to the hydrogen supply channel 31 are provided.

  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.

  Each hydrogen tank 30 is provided with a high pressure sensor (second pressure sensor) 44 for detecting the internal pressure. In FIG. 1, only one hydrogen tank 30 is shown, and the other three The illustration of the hydrogen tank 30 is saved.

  The hydrogen supply channel 31 includes a shutoff valve 33 that shuts off or allows the supply of hydrogen gas from the hydrogen tank 30, a regulator (pressure regulating valve) 34 that adjusts the pressure of the hydrogen gas, and an injector (flow rate regulating valve) 35. , Is provided. A primary pressure sensor (first pressure sensor) 41 and a temperature sensor 42 for detecting the pressure and temperature of the hydrogen gas in the hydrogen supply channel 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 (pressure adjusting valve) that reduces (regulates) 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.

  The injector 35 is an electromagnetically driven on-off valve capable of adjusting the gas flow rate and gas pressure by driving the valve body directly with a predetermined driving cycle with an electromagnetic driving force and separating it from the valve seat. The injector 35 includes a valve seat having an injection hole for injecting gaseous fuel such as hydrogen gas, a nozzle body for supplying and guiding the gaseous fuel to the injection hole, and an axial direction (gas flow direction) with respect to the nozzle body. And a valve body that is movably accommodated and opens and closes the injection hole.

  In the present embodiment, the valve body of the injector 35 is driven by a solenoid that is an electromagnetic drive device, and the opening area (opening state) of the injection hole is set in two stages by turning on and off the pulsed excitation current supplied to the solenoid. It is possible to switch to the above multi-stage or stepless.

  Injector 35 changes the at least one of the opening / closing state (opening) and the opening time of the valve body provided in the gas flow path of injector 35 in order to supply the required gas flow rate downstream thereof. The gas flow rate (or hydrogen molar concentration) supplied to the side (fuel cell 10 side) is adjusted.

  Since the gas flow rate is adjusted by opening and closing the valve body 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. As shown in FIG. 1, when a plurality of hydrogen tanks 30 are used as the fuel supply source, the downstream side of the portion where the hydrogen gas supplied from each hydrogen tank 30 joins (hydrogen gas joining portion A <b> 2). The injector 35 is arranged at the position.

  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.

  The control device 4 controls the gas injection time and gas injection timing of the injector 35 by outputting a control signal for realizing the total injection time of the injector 35 calculated through a predetermined procedure, so that the fuel cell 10 The flow rate and pressure of the supplied hydrogen gas 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 fuel cell system 1 of the present embodiment, the control device 4 monitors the remaining amount of hydrogen gas in the hydrogen tank 30 based on the detection result from the primary pressure sensor 41.

  Here, as shown in FIG. 2, the pressure on the primary side in the pipe between the injector 35 and the regulator 34 is such that when the injector 35 is opened (the valve body is separated from the valve seat), the hydrogen gas flows to the secondary side. When the injector 35 is sent out and is greatly reduced and the injector 35 is closed (the valve body abuts on the valve seat), it rises again by the hydrogen gas flowing in from the hydrogen tank 30. Therefore, in the pipe between the injector 35 and the regulator 34, the valve body is opened and closed at a high speed in the injector 35, so that the pressure repeatedly fluctuates greatly and pulsates greatly (see t1 in FIG. 2).

  However, when the remaining amount of hydrogen gas in the hydrogen tank 30 decreases and the internal pressure becomes equal to or lower than the set pressure of the regulator 34, the opening state of the regulator 34 disposed in the hydrogen supply path 31 communicating with the hydrogen tank 30. Therefore, the volume on the primary side upstream of the injector 35 includes not only the piping between the injector 35 and the regulator 34 but also the space of the gas phase portion of the hydrogen tank 30. For this reason, the pressure fluctuation caused by the opening / closing movement of the valve body in the injector 35 is reduced, and the width of the pressure pulsation is drastically reduced (see t2 in FIG. 2).

  The control device 4 obtains the change amount Pa of the pressure pulsation based on the detection result from the primary pressure sensor 41, and monitors the remaining amount of hydrogen gas in the hydrogen tank 30 from the change amount Pa. Further, the pulsation change amount Pa due to the decrease in the remaining amount of hydrogen gas varies depending on the number of hydrogen tanks 30 to be used. Specifically, as shown in FIG. 3, as the quantity of the hydrogen tank 30 used increases, the amount of increase in the upstream volume of the injector 35 when the regulator 34 is fully opened increases. The amount of change Pa also increases.

  Next, the monitoring control of the remaining amount of hydrogen gas by the control device 4 will be described in detail. FIG. 4 is a flowchart showing the flow of remaining amount monitoring control by the control device. First, the control device 4 sets a determination value Pb of the pressure pulsation change amount Pa from a predetermined map based on the usage amount of the hydrogen tank 30 (step S01).

  Next, based on the detected pressure from the primary pressure sensor 41, the control device 4 determines that the regulator 34 is fully opened and the pulsation variation Pa due to the opening / closing movement of the valve body of the injector 35 is equal to or greater than the determination value Pb. (Step S02), it is determined that the remaining amount of the hydrogen tank 30 is a small amount less than a predetermined value. Whether the regulator 34 is fully open is determined based on a detection result from a proximity sensor or the like that detects the valve opening of the regulator 34. Then, a signal is transmitted from the control device 4 to, for example, a warning lamp, and a decrease in hydrogen gas is notified by an alarm.

  Thus, according to the fuel cell system 1 according to the above embodiment, compared with the remaining amount monitoring by the high pressure sensor 44 that detects the pressure of the hydrogen tank 30, based on the state of pressure pulsation due to the operation of the injector 35, The remaining amount of hydrogen gas can be monitored well with high accuracy and high reliability. Moreover, the high-pressure sensor 44 can be omitted, and the system can be simplified and the cost can be reduced.

  Note that the pressure pulsation due to the opening and closing movement of the valve body of the injector 35 and the change in the pressure pulsation due to the decrease in hydrogen gas also occur on the secondary side downstream of the injector 35. Therefore, the remaining amount of hydrogen gas may be monitored based on the detected pressure from the secondary pressure sensor 43.

  Further, in order to obtain the remaining amount of hydrogen gas in the hydrogen tank 30, a high pressure sensor that detects the pressure of the hydrogen tank 30 is provided, along with monitoring the remaining amount of hydrogen gas based on the detection result from the high pressure sensor, The remaining amount may be monitored, and when an abnormality occurs in this high-pressure tank, the remaining amount may be monitored by a change in pressure pulsation, thereby improving the reliability of monitoring the remaining amount of hydrogen gas. Can be increased.

  In the above embodiment, the case where a plurality of hydrogen tanks 30 are simultaneously used has been described as an example. However, a plurality of hydrogen tanks 30 may be used in order, and in this case, the remaining amount monitoring by the change in pressure pulsation is performed. When the remaining amount of the used hydrogen tank 30 decreases to a predetermined remaining amount, the other hydrogen tank 30 is switched.

  In the above embodiment, the case where the flow rate adjustment valve including the injector 35 for controlling the supply amount of the hydrogen gas is described as an example. However, the supply amount of the hydrogen gas is adjusted by a variable pressure regulator instead of the injector 35. In this case, the control device 4 monitors the remaining amount of hydrogen gas in the hydrogen tank 30 based on a change in pulsation due to opening and closing of the valve of the adjustable pressure regulator.

1 is a configuration diagram of a fuel cell system according to an embodiment of the present invention. It is a graph explaining the pressure pulsation of the primary side. It is a graph which shows the variation | change_quantity of the pressure pulsation by the usage-amount of a hydrogen tank. It is a flowchart which shows the flow of remaining amount monitoring control by a control apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Fuel cell system, 4 ... Control apparatus (monitoring part), 10 ... Fuel cell, 30 ... Hydrogen tank (tank), 34 ... Regulator (regulator), 35 ... Injector (flow control valve), 41 ... Primary pressure Sensor (first pressure sensor), 44... High pressure sensor (second pressure sensor).

Claims (12)

A fuel cell system in which a reaction gas supplied from a tank in which a reaction gas is stored at a predetermined pressure higher than normal pressure is adjusted to a predetermined flow rate by a flow rate adjustment valve and is supplied to the fuel cell,
A fuel cell system comprising a monitoring unit that monitors the remaining amount of the reaction gas in the tank based on the state of pressure pulsation detected by a first pressure sensor disposed downstream of the flow rate adjustment valve . The fuel cell system according to claim 1,
A fuel cell system comprising an electromagnetically driven on / off valve as the flow rate adjusting valve, wherein the valve body is driven by an electromagnetic driving force at a predetermined driving cycle to be separated from the valve seat. The fuel cell system according to claim 1,
A fuel cell system comprising a variable pressure regulator having a variable target pressure regulation value as the flow rate adjustment valve. The fuel cell system according to any one of claims 1 to 3,
The said monitoring part is a fuel cell system which determines with the reactive gas in the said tank being less than predetermined amount based on the state of the pressure pulsation detected by the said 1st pressure sensor. The fuel cell system according to claim 4, wherein
The fuel cell system, wherein the monitoring unit determines that the reaction gas in the tank is less than a predetermined amount when a pressure pulsation detected by the first pressure sensor decreases. The fuel cell system according to claim 4, wherein
The fuel cell system in which the monitoring unit determines that the reaction gas in the tank is less than a predetermined amount when the amount of change in pressure pulsation detected by the first pressure sensor becomes a predetermined determination value or more. . The fuel cell system according to any one of claims 1 to 6,
The said monitoring part is a fuel cell system which sets the determination standard of the residual amount of the reactive gas based on the pressure pulsation detected by the said 1st pressure sensor according to the quantity of the said tank. The fuel cell system according to any one of claims 1 to 7,
A second pressure sensor for detecting the pressure in the tank;
The said monitoring part is a fuel cell system which monitors the residual amount of the reactive gas in the said tank based on the pressure pulsation detected by the said 1st pressure sensor, and the detection result of the said 2nd pressure sensor. The fuel cell system according to claim 8, wherein
The monitoring unit is a fuel cell system that monitors the remaining amount of reaction gas in the tank based on the state of pressure pulsation detected by the first pressure sensor when the second pressure sensor is abnormal. The fuel cell system according to any one of claims 1 to 9,
A plurality of the tanks;
A fuel cell system in which a used tank is switched to another tank when the remaining amount of reaction gas in the used tank becomes less than a predetermined value. After the reaction gas supplied from a tank in which the reaction gas is stored at a predetermined pressure higher than the normal pressure is regulated by a pressure regulating valve, a predetermined flow rate is provided by the flow rate adjusting valve disposed downstream of the pressure regulating valve. A fuel cell system that adjusts to supply to a fuel cell,
A fuel cell system comprising a monitoring unit that monitors the remaining amount of reaction gas in the tank based on an opening state of the pressure regulating valve. The fuel cell system according to claim 11, wherein
The monitoring unit is a fuel cell system that determines that the reaction gas in the tank is less than a predetermined value when the pressure regulating valve is fully opened.

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