JP2008112647A - Vehicular fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To allow flooding of a fuel cell to be eliminated and prevented in running state of vehicles on climbing lanes or other roads. <P>SOLUTION: A vehicular fuel cell system 20 comprises a tilt sensor 30 for detecting inclination of vehicles, a vehicle speed detection means 32 for detection of the vehicle speed to determine the gas flow rate, a fuel cell power generator 60, and a controller 40. The controller 40 includes a memory 52 for storing flooding determination maps and a CPU 41. A flooding determination module 42 on the CPU 41 determines flooding status, especially probability of flooding occurrence by referring to the flooding determination map in accordance with inclination and speed of vehicles, while a flooding prevention startup module 44 starts means for preventing flooding such as increased gas flow rate, increased temperature of fuel cell cooling water, execution of purging, power supply switching and the like in accordance with the flooding determination results. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a vehicle fuel cell system, and more particularly to a vehicle fuel cell system that controls flooding of a fuel cell mounted on a vehicle.

  Since there is little impact on the environment, fuel cells are installed in vehicles. In the fuel cell, for example, a fuel gas such as hydrogen is supplied to the anode side of the fuel cell stack, a reaction gas containing oxygen such as air is supplied to the cathode side, and necessary electric power is taken out by an electrochemical reaction through the electrolyte membrane. At that time, water is generated by an electrochemical reaction on the cathode side.

  When this water stays on the cathode or passes through the electrolyte membrane and stays on the anode side, the pores of the electrode base material such as the gas diffusion layer are blocked to inhibit gas diffusion. This phenomenon is called flooding. When flooding occurs, the output of the fuel cell decreases, and measures are taken. As described above, flooding refers to a gas flow path for flowing fuel gas or oxidizing gas to a fuel cell that is a unit cell constituting a fuel cell, a gas expansion that forms the fuel cell, and a gas system that flows to each fuel cell. In a fuel cell such as a manifold, the amount of water present as a liquid is large.

  For example, in Patent Document 1, when the output voltage E of the fuel cell is smaller than a predetermined voltage value E1 and the impedance Z is smaller than the predetermined impedance value Z1, it is determined that the cathode is too wet and adheres to the surface of the cathode by several methods. It is disclosed to blow off water droplets quickly. Here, a combination of increasing the bypass flow rate of oxygen gas, increasing the amount of circulating oxygen gas, and lowering the exhaust gas back pressure is described.

JP 7-235324 A

  By the way, depending on the running state of the vehicle, flooding may be particularly likely to occur. For example, when the vehicle climbs a hill, the fuel cell tilts, and the generated water tends to accumulate in a specific place due to the influence of gravity, and flooding is likely to occur. In particular, when traveling on a hill at low speed, the fuel cell does not generate much power, so the flow rate of gas is small and the generated water is less removed by the flow of gas, and flooding is more likely to occur. As such a case, it is conceivable to go out from the underground parking lot.

  The conventional technology is insufficient in terms of measures for solving or preventing such a case where flooding is likely to occur depending on the traveling state of the vehicle on such an uphill road.

  An object of the present invention is to provide a fuel cell system for a vehicle that can eliminate or prevent flooding of the fuel cell in a traveling state of the vehicle such as an uphill road.

  A fuel cell system for a vehicle according to the present invention includes a tilt sensor that detects a tilt of a fuel cell mounted on a vehicle or a tilt of the vehicle, an estimation unit that estimates a gas flow rate of the fuel cell, a detection result of the tilt sensor, Judgment means for judging the flooding status of the fuel cell according to a predetermined judgment condition based on the estimation result of the estimation means.

  Further, the vehicle fuel cell system according to the present invention preferably includes a preventive activation unit that activates the flooding elimination / prevention unit based on the result of the determination unit.

  In the vehicle fuel cell system according to the present invention, the flooding elimination / prevention means is preferably fuel gas increase means for increasing the flow rate of the fuel gas supplied to the fuel cell. The flooding elimination / prevention means is preferably cooling water temperature raising means for raising the temperature of the cooling water for the fuel cell. Further, the flooding elimination / prevention means is preferably purge execution means for executing a purge for blowing off moisture using fuel gas or oxidizing gas of the fuel cell.

  Further, the vehicle fuel cell system according to the present invention preferably includes power supply switching means for causing the vehicle to run with the power of the secondary battery instead of the fuel cell based on the result of the determination means.

  In the vehicular fuel cell system according to the present invention, it is preferable that the estimating means estimates the gas flow rate based on the generated current of the fuel cell.

  With the above configuration, the vehicular fuel cell system determines the flooding state according to a predetermined determination condition based on the detection result of the inclination of the vehicle or the fuel cell and the estimation result of the gas flow rate. Therefore, it is possible to determine the flooding state of the fuel cell in the traveling state of the vehicle such as an uphill road.

  Further, the flooding elimination / prevention means is activated based on the result of the flooding determination. Therefore, flooding of the fuel cell can be eliminated or prevented in the traveling state of the vehicle such as an uphill road.

  Further, the flow rate of the fuel gas is increased, the temperature of the cooling water of the fuel cell is increased, or the purge for blowing off the moisture using the fuel gas or the oxidizing gas is executed. Thereby, flooding of the fuel cell can be eliminated or prevented.

  Further, since the vehicle is driven by the power of the secondary battery instead of the fuel cell, the vehicle is not hindered even if the flooding is not eliminated.

  Further, since the gas flow rate is estimated based on the generated current of the fuel cell, no special sensor is required.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Below, although demonstrated as what arrange | positions a fuel cell to the front side of a vehicle, the mounting method to the vehicle of a fuel cell may be other than this. For example, the fuel cell may be disposed under the floor in the middle of the vehicle or at the rear of the vehicle. In the following description, it is assumed that flooding occurs on the fuel gas side. However, flooding may occur in the oxidizing gas flow path. In this case, the increase or purge of the oxidizing gas flow for eliminating / preventing flooding is performed by controlling the air compressor.

  FIG. 1 is a diagram showing a configuration of a vehicle fuel cell system 20. FIG. 1 shows a road 8 and a vehicle 10 that are not components of the vehicle fuel cell system 20. The vehicle fuel cell system 20 is a system that performs operation of a fuel cell mounted on the vehicle 10, and in particular, a function of eliminating and preventing flooding of the fuel cell when the vehicle 10 travels on an inclined road 8. Have

  The vehicle fuel cell system 20 includes an inclination sensor 30 that detects the inclination of the vehicle, vehicle speed detection means 32 that detects the vehicle speed in order to estimate the gas flow rate of the fuel cell, a fuel cell power generation unit 60, and a control unit. 40. The control unit 40 includes a CPU 41, a storage unit 52 for storing a map for determining a flooding state from the vehicle inclination and vehicle speed, and an inclination sensor I / F (54) that is an interface with the inclination sensor 30. And a vehicle speed I / F (56) which is an interface with the vehicle speed detecting means. These elements are connected to each other by an internal bus. Such a control unit 40 can be configured by an in-vehicle computer. The control unit 40 can be configured as an independent computer as a fuel cell control computer, or can be configured as a part of the function of another in-vehicle computer. For example, when the vehicle includes a hybrid CPU or the like related to its operation or the like, the function of the control unit 40 may be configured as a part of the function of the hybrid CPU.

  The inclination sensor 30 is a measuring instrument that is attached to the vehicle body of the vehicle 10 and has a function of detecting the inclination angle of the vehicle body with respect to the horizon. Since the inclination angle of the vehicle body is detected in order to detect the inclination of the fuel cell stack, the inclination sensor may be directly attached to the fuel cell stack. The detection direction of the inclination of the inclination sensor 30 differs depending on the arrangement direction of the fuel cell stack, but generally, the fuel cell stack is assumed to be parallel or orthogonal to the vehicle front-rear axis, and the vehicle front-rear axis is assumed. The inclination angle of is detected. That is, the inclination angle between the front part and the rear part of the vehicle is detected in the traveling direction of the vehicle. As such an inclination sensor, an angle meter, a level meter or the like can be used.

  The vehicle speed detection means 32 has a function of detecting the speed of the vehicle in order to estimate the gas flow rate of the fuel cell. For example, a vehicle speed sensor used for vehicle operation control can be used as it is. That is, when the vehicle speed is low, the load on the fuel cell is light, and therefore the gas flow rate is small. On the other hand, when the speed of the vehicle is high, the load on the fuel cell is heavy, and therefore the gas flow rate increases. In this way, the gas flow rate can be estimated from the detection of the vehicle speed.

  Thus, the estimation of the gas flow rate of the fuel cell can be performed based on the detection of the vehicle speed. In addition to this, the estimation of the flow rate of the fuel gas is based on the operating state of the fuel gas pump, the operating state of the fuel gas supply opening / closing valve provided in the fuel gas flow path, the operating state of the air compressor supplying the oxidizing gas, This can be performed based on an output state such as a current. Those having the function of estimating the gas flow rate based on these detection means can be referred to as gas flow rate estimation means. The gas flow rate estimating means can be a function of the control unit. For example, in the example of FIG. 1, a function of estimating the gas flow rate based on the vehicle speed detection unit 32 can be provided in the CPU 41 of the control unit 40.

  The flooding determination map stored in the storage unit 52 is data that associates the state of occurrence of flooding in the fuel cell with the running state of the vehicle. Here, in particular, the flooding state, particularly the possibility of occurrence of flooding, is mapped and stored in association with the vehicle inclination angle θ and the vehicle speed V. That is, as will be described later, when the vehicle tilts, the fuel cell stack tilts, and the water generated by the electrochemical reaction of the fuel cell is affected by gravity, the geometric shape of the fuel cell stack, and the like. It happens that it tends to accumulate in a specific part of the stack. As the inclination angle θ increases, the tendency becomes stronger and flooding is likely to occur. Further, when the vehicle speed is low, the amount of power generated by the fuel cell decreases, the flow rate of the fuel gas or the oxidizing gas decreases, and the ability to carry the generated water to the outside decreases. The lower the vehicle speed, the stronger the tendency and the more likely flooding occurs. Therefore, a flooding determination map can be created by obtaining the possibility of flooding in advance for the vehicle inclination angle θ and the vehicle speed V and associating them with each other.

  Since the flooding state includes the case where flooding has already occurred, the degree of flooding is further increased when flooding has already occurred and the vehicle is further inclined.

  The flooding determination map is a map obtained by quantifying the possibility of occurrence of flooding using the vehicle inclination angle θ and the vehicle speed V as parameters. Further, instead of the map, the data can be stored as a data structure that can search for the numerical data of the possibility of flooding using the vehicle inclination angle θ and the vehicle speed V as search keys. Conversely, using the numerical value of the possibility of flooding as a search key, the tilt angle θ and the vehicle speed V at that time can also be searched.

  The numerical value of the possibility of occurrence of flooding may be a ranking numerical value or may indicate the probability of occurrence of flooding in%. For example, for the combination of (inclination angle θ, vehicle speed V), the possibility of occurrence of flooding is evaluated as 0, 1, 2, 3, 4, 5 and evaluated when (θ = 30 °, V = 10 km) = When 2 or occurrence probability = 40%, (θ = 30 °, V = 30 km), it can be stored as evaluation = 1 or occurrence probability = 20%.

  The CPU 41 includes a fuel cell operation module 50 that controls the overall operation of the fuel cell power generation unit 60. Here, in particular, the flooding determination module 42 that determines the state of flooding by referring to the flooding determination map based on the vehicle inclination and the vehicle speed, and the flooding elimination / prevention means are activated based on the result of the flooding determination. And an anti-flooding activation module 44. The anti-flooding activation module 44 can select several solutions / prevention means depending on the flooding state, particularly the possibility of occurrence of flooding. Specifically, means 45 for increasing the fuel gas flow rate, means 46 for increasing the fuel cell cooling water temperature, purge execution means 47 for blowing off flooding water, and switching the power source from the fuel cell to the secondary battery The means 48 has a function of activating according to the magnitude of the possibility of flooding. These functions can be realized by software. Specifically, the functions can be realized by executing a corresponding fuel cell operation program, in particular, a flooding prevention program as a part thereof. Some of these functions can also be realized by hardware.

  FIG. 2 is a diagram illustrating the configuration of the fuel cell power generation unit 60. Under the control of the fuel cell operation module 50 of the control unit 40, the fuel cell power generation unit 60 supplies the fuel cell stack 22 with hydrogen, which is a fuel gas, and pressurized air, which is an oxidant gas. It is a device that takes out electric power and operates. The electric power generated by the fuel cell power generation unit 60 is adjusted with the electric power from the secondary battery 14 in the power distribution unit 16 under the control of the control unit 40 and supplied to the load 12 such as a motor / generator of the vehicle. Is done.

  The fuel cell power generation unit 60 includes a fuel cell body called a fuel cell stack 22 in which a plurality of fuel cells are stacked, elements for supplying hydrogen gas arranged on the anode side of the fuel cell stack 22, and a cathode side. It is comprised including each element for the air supply arrange | positioned.

  The anode-side hydrogen gas source 62 is a tank that supplies hydrogen as a fuel gas. The hydrogen gas source 62 is connected to the regulator 64. The regulator 64 has a function of adjusting the gas from the hydrogen gas source 62 to an appropriate pressure and flow rate. The output port of the regulator 64 is connected to the anode side inlet of the fuel cell stack 22, and fuel gas adjusted to an appropriate pressure and flow rate is supplied to the fuel cell stack 22.

  The gas discharged from the anode side outlet of the fuel cell stack 22 consumes hydrogen during power generation, resulting in a low hydrogen concentration, and nitrogen gas, which is a component of the cathode side air, permeates through the MEA (Mebrane Electrode Assembly). As a result, the impurity gas concentration is high. The reaction product water also permeates through the MEA. When this permeating water becomes excessive, flooding occurs.

  The exhaust valve 68 connected to the anode side outlet of the fuel cell stack 22 is for flowing into the diluter 78 when the impurity gas concentration of the exhaust gas from the anode side outlet increases. The exhaust gas at this time is a hydrogen gas containing reaction product water in addition to nitrogen. In addition, the circulation booster 66 provided between the anode side outlet and the anode side inlet increases the hydrogen partial pressure of the gas returning from the anode side outlet, and returns to the anode side inlet for reuse again. It is.

  The cathode-side oxidizing gas supply source 70 can actually use air. An air compressor (ACP) 72 connected to an oxidizing gas supply source 70 that is the atmosphere is a gas booster that compresses the volume of oxidizing gas by a motor (not shown) to increase its pressure. In addition, the ACP (72) has a function of providing a predetermined amount of oxidizing gas by varying the rotation speed (the number of rotations per minute) under the control of the control unit 60. That is, when the required flow rate of the oxidizing gas is large, the rotational speed of the motor is increased. Conversely, when the required flow rate of the oxidizing gas is small, the rotational speed of the motor is decreased. Thus, the oxidizing gas, which is oxygen-containing air, is supplied to the cathode side of the fuel cell stack 22 by the ACP (72).

  The humidifier 74 has a function of appropriately moistening the oxidizing gas and efficiently performing the fuel cell reaction in the fuel cell stack 22. The oxidizing gas appropriately moistened by the humidifier 74 is supplied to the cathode side inlet of the fuel cell stack 22 and exhausted from the cathode side outlet. At this time, water as a reaction product is also discharged together with the exhaust. Since the fuel cell stack 22 becomes a high temperature due to the reaction, the water contained in the discharged gas is water vapor, and this water vapor is supplied to the humidifier 74, and the oxidizing gas supplied from the ACP (72) is moderately adjusted. Moisten. Thus, the humidifier 74 has a function of appropriately giving moisture of water vapor to the oxidizing gas, and a gas exchanger using a so-called hollow fiber can be used. That is, the humidifier 74 is configured to be able to exchange gas between a flow path through which the oxidizing gas from the ACP (72) flows and a flow path through which the exhaust gas containing water vapor flows. For example, the hollow fiber inner flow path is used as the oxidizing gas flow path from the ACP (72), and the hollow fiber outer flow path is used as the exhaust gas flow path containing water vapor from the cathode side outlet of the fuel cell stack 22. Thus, the oxidizing gas to the cathode side inlet of the fuel cell stack 22 can be appropriately moistened.

  The bypass valve 76 is arranged in parallel with the fuel cell stack 22 by connecting an inlet side flow channel through which the oxidizing gas is supplied to the fuel cell stack 22 and an outlet side flow channel through which the exhaust gas from the fuel cell stack 22 flows. This valve is provided in the bypass flow path, and mainly has a function of supplying air for diluting the hydrogen concentration in the exhaust gas to the diluter 78. That is, by opening the bypass valve 76, the oxidizing gas from the ACP (72) separates from the component flowing into the fuel cell stack 22 and does not flow through the fuel cell stack 22, but passes through the bypass flow path to the diluter 78. Can be supplied to.

  The diluter 78 collects the wastewater containing hydrogen from the exhaust valve 68 on the anode side and the exhaust gas containing hydrogen leaking through the MEA due to the water vapor on the cathode side, and discharges it to the outside as an appropriate hydrogen concentration. It is a buffer container. When the hydrogen concentration exceeds an appropriate concentration, further appropriate dilution can be performed using the supply gas provided without passing through the fuel cell stack 22 by opening the bypass valve 76.

  The circulation pump 80 is for circulating the cooling water so that the temperature of the fuel cell stack 22 becomes a temperature suitable for the electrochemical reaction. A heat exchanger 82 for exchanging heat with the cooling water is provided in the cooling water circulation passage. As the heat exchanger 82, a combination of a radiator and a heater can be used. Alternatively, a refrigerant / water heat exchanger that exchanges heat with the refrigerant for air conditioning in the passenger compartment may be used.

  FIG. 3 is a diagram showing the configuration of the fuel cell stack 22. The fuel cell stack 22 combines a plurality of single cells 92 into a high voltage battery pack. For example, about 200 single cells having a terminal voltage of about 1.2V are connected in series, and two sets of these are combined to use a high voltage battery pack of about 250V or about 500V using a total of about 400 single cells. can do. The fuel cell stack 22 is a combination of a plurality of unit cells 92, and includes a manifold 90 for supplying fuel gas and oxidizing gas to these unit cells 92 and circulating cooling water. The manifold 90 is provided with a plurality of ports 91 for gas and cooling water to enter and exit.

  FIG. 3 shows two unit cells 92 constituting a fuel cell stack 22 with a part thereof broken. The unit cell 92 includes an MEA 93 and separators 94 provided on both sides thereof. The MEA 93 has a configuration in which a catalyst layer and a gas diffusion layer are laminated on both sides of the electrolyte membrane. The separator 94 is provided therein with a fuel gas flow path, an oxidizing gas flow path, and a cooling water flow path. FIG. 3 shows a fuel gas flow path as a part thereof. Has been. The fuel gas 96 that is hydrogen gas is discharged from the fuel gas supply port connected to the port of the manifold 90 through the meandering flow path provided in the separator 94 and is also connected to the port of the manifold 90. It flows toward the exit. Meanwhile, the fuel gas is supplied to the MEA 93 with which the separator 94 is in contact.

  The fuel gas 96 includes generated water that permeates from the cathode side through the MEA 93 when flowing through the separator 94. The generated water is discharged to the outside together with the fuel gas flowing through the separator 94 from the fuel gas discharge port. However, if the fuel cell stack 22 is inclined, it is collected at a specific location 98 due to the influence of gravity. It becomes easy. For example, when the vehicle leaves the underground parking lot, it travels on an inclined surface at a low speed. At this time, the vehicle tilts and the fuel cell stack 22 tilts. Here, with respect to the two unit cells of each layer stacked on the fuel cell stack 22, in one unit cell on the upper side of the slope, the influence of gravity is favorable for the discharge of the generated water. In the other unit cell on the lower side of the slope, the influence of gravity works unfavorably on the discharge of the generated water, and the generated water tends to collect at a specific portion 98 on the bottom on the discharge side. In this specific portion 98, so-called flooding is likely to occur.

  In FIG. 3, the fuel cell stack 22 is arranged with the width direction of the vehicle as the stacking direction of the unit cells 92. In this case, as described above, flooding is likely to occur unevenly in the plane of the unit cell 92. That is, such an arrangement is particularly suitable for diagnosing the distribution of the flooding state in the plane of the unit cell 92.

  The fuel cell stack 22 may be arranged such that the front-rear direction of the vehicle is the stacking direction of the unit cells 92. FIG. 4 is a diagram showing a situation when flooding occurs in the fuel cell stack 22 in such an arrangement. Elements similar to those in FIG. 3 are denoted by the same reference numerals, and detailed description thereof is omitted. Here, the arrow direction indicates the front-rear direction of the vehicle, and the stacking direction of the cells 92 in the fuel cell stack 22 is along the direction of the arrow. In this case, when the vehicle is on the inclined surface, the fuel cell stack 22 is inclined along the stacking direction of the unit cells 92. At this time, among the stacks, the unit cells in the stacks on the upper side of the slope are unlikely to collect generated water, whereas in the single cells in the stack on the lower side of the tilt, at a specific portion 98 at the bottom, The generated water tends to accumulate due to the influence of gravity. In this specific portion 98, so-called flooding is likely to occur.

  As described above, in FIG. 4, flooding is likely to occur so as to be biased among the single cells 92 along the stacking direction of the fuel cell stack 22. Therefore, such an arrangement is particularly suitable for diagnosing the distribution of the condensed water among the single cells 92, that is, the distribution of the flooding state.

  The operation of the vehicular fuel cell system having such a configuration, in particular, the contents of each function in the CPU 41 of the control unit 40 will be described. First, fuel cell power generation control in a normal case will be described, and then flooding elimination / prevention control will be described with reference to the flowchart of FIG.

  In a normal case, the fuel cell power generation unit 60 performs desired power generation under the control of the fuel cell operation module 50 of the control unit 40. That is, when the power generation amount of the fuel cell is commanded to the control unit 40 from a vehicle operation control unit or the like that controls the operation of the vehicle, the control unit 40 selects the fuel gas pressure and flow rate corresponding to the commanded power generation amount. Further, the pressure and flow rate of the oxidizing gas are calculated, and the regulator 64 and the ACP (72) are instructed to supply predetermined fuel gas and oxidizing gas to the fuel cell stack 22, respectively. Further, the temperature of the fuel cell stack 22 is obtained from the cooling water temperature or the like, and the temperature and flow rate of the cooling water are calculated so as to be suitable for the electrochemical reaction, and the circulation pump 80 and the heat exchanger 82 are connected. Command and circulate the prescribed cooling water. Then, the power output from the fuel cell stack 22 is compared with the required power of the load 12, and the power distribution unit 16 is instructed to perform switching adjustment between the power from the secondary battery 14. In this way, the operation of the fuel cell power generation unit 60 is controlled, and desired power is supplied to the load 12.

  FIG. 5 is a flowchart showing a procedure for eliminating or preventing flooding. Each procedure in FIG. 5 corresponds to each processing procedure of the flooding prevention program that constitutes a part of the corresponding fuel cell operation program. In the following, the symbols in FIGS. 1 to 4 are used.

  The first step in eliminating / preventing the flooding of the fuel cell is to detect the vehicle inclination angle θ and the vehicle speed V (S10). The inclination angle θ is detected by the CPU 41 acquiring the output of the inclination sensor 30 provided on the vehicle 10 via the inclination sensor I / F (54), and the vehicle speed V is detected on the vehicle speed provided on the vehicle 10. This is done by the CPU 41 obtaining the output of the detection means 32 via the vehicle speed I / F (56). When the inclination angle θ and the vehicle speed V are acquired, it is determined whether flooding is easy with reference to the flooding determination map stored in the storage unit 52 (S12). These functions are executed by the flooding determination module 42 in the CPU 41 of the control unit 40.

  For example, whether or not flooding is easy is determined by searching a flooding determination map using a combination of detected (tilt angle θ and vehicle speed V) as a search key, obtaining an evaluation or probability of the occurrence of flooding, and determining in advance. This can be done by comparing with a standard. For example, when it is determined that it is determined that flooding is likely to occur when the evaluation of occurrence of flooding is 2 or more, if (θ = 30 °, V = 10 km) is detected in the above example, this is evaluated. Since = 2, it is determined that flooding is easy. For example, if (θ = 30 °, V = 30 km) is detected, since evaluation = 1, it is not determined that flooding is likely to occur according to the above criteria.

  If it is determined that flooding is likely to occur, then the flooding elimination / prevention means is activated in accordance with the evaluation or probability of occurrence of flooding (S14 to S26). This function is executed by the flooding prevention activation module 44 of the CPU 41. As the flooding elimination / prevention means, means 45 for increasing the fuel gas flow rate, means 46 for increasing the fuel cell cooling water temperature, purge execution means 47 for blowing off flooding water, and from the fuel cell to the secondary battery There are means 48 for switching the power supply, and these are selected to be executed according to the evaluation or probability of occurrence of flooding.

  For example, when the evaluation of occurrence of flooding is 2, the means 45 for increasing the fuel gas flow rate is activated (S14). Specifically, in FIG. 2, a command is issued to the regulator 64 to increase the flow rate of the fuel gas by a predetermined amount.

  When the evaluation of occurrence of flooding is 3, it can be determined that the increase in the fuel gas flow rate alone is insufficient for eliminating and preventing flooding (S16). In this case, the means 46 for increasing the fuel cell cooling water temperature is further activated (S18). Specifically, a command is issued to the circulation pump 80 to reduce the flow rate of the circulating water, thereby increasing the temperature of the cooling water. Further, if necessary, a command is issued to the heat exchanger 82 to heat the cooling water.

  If the evaluation of occurrence of flooding is 4, it can be determined that only (increase in fuel gas flow rate + increase in fuel cell cooling water temperature) is insufficient for eliminating and preventing flooding (S20). In this case, the purge execution means 47 for blowing off flooding water is further activated (S22). Specifically, a command is issued to the regulator 64, the flow rate of the fuel gas is intermittently increased and decreased, and the generated water is blown off by the change.

  If the evaluation of occurrence of flooding is 5, it can be determined that (fuel gas flow rate increase + fuel cell cooling water temperature increase + purge) alone is insufficient for eliminating / preventing flooding (S24). In this case, power supply switching is executed (S26). That is, a command is issued to the power distribution unit 16 so that the power of the secondary battery 14 is supplied to the load 12 so as not to hinder the operation of the vehicle 10.

  Thus, according to the evaluation of occurrence of flooding, the flooding elimination / prevention means can be selected and appropriate processing can be executed. Instead of evaluating the occurrence of flooding, the flooding elimination / prevention means may be selected based on the flooding occurrence probability.

  The selection order of the above four cancellation / prevention means may be determined in advance, and may be a selection order other than the above.

  In addition, whether or not it is easy to flood is set to 0 or 1, and when it is determined that flooding is likely to occur, it is most executed according to the running state of the vehicle from among the above four elimination / prevention means. It is good also as selecting what is easy to do. Or it is good also as what performs a several thing out of four cancellation | release / prevention means.

In embodiment which concerns on this invention, it is a figure which shows the structure of the fuel cell system for vehicles. In the embodiment according to the present invention, it is a diagram illustrating the configuration of the fuel cell power generation unit. FIG. 3 is a diagram showing a configuration of a fuel cell stack in the embodiment according to the present invention. In embodiment which concerns on this invention, it is a figure which shows another arrangement | positioning of a fuel cell stack. 5 is a flowchart showing a procedure for eliminating / preventing flooding in the embodiment according to the present invention.

Explanation of symbols

  8 road, 10 vehicle, 12 load, 14 secondary battery, 16 power distribution unit, 20 fuel cell system for vehicle, 22 fuel cell stack, 30 tilt sensor, 32 vehicle speed detection means, 40 control unit, 41 CPU, 42 flooding judgment Module, 44 Flooding prevention activation module, 45 Fuel gas increase means, 46 Cooling water temperature increase means, 47 Purge execution means, 48 Power supply switching means, 50 Fuel cell operation module, 52 Storage section, 54 Inclination sensor I / F, 56 Vehicle speed I / F, 60 Fuel cell power generation unit, 62 Hydrogen gas source, 64 Regulator, 66 Circulating booster, 68 Exhaust valve, 70 Oxidizing gas supply source, 72 ACP, 74 Humidifier, 76 Bypass valve, 78 Diluter, 80 Circulation pump, 82 heat exchanger, 90 manifold, 91 ports , 92 Single cell, 93 MEA, 94 Separator, 96 Fuel gas, 98 Easy to collect.

Claims (7)

An inclination sensor for detecting the inclination of the fuel cell mounted on the vehicle or the inclination of the vehicle;
An estimation means for estimating the gas flow rate of the fuel cell;
A determination means for determining the flooding status of the fuel cell according to a predetermined determination condition based on the detection result of the inclination sensor and the estimation result of the estimation means;
A vehicle fuel cell system comprising: The vehicle fuel cell system according to claim 1,
A vehicle fuel cell system comprising: a preventive starting unit that starts a flooding elimination / prevention unit based on a result of the determination unit. The vehicle fuel cell system according to claim 2,
The vehicle fuel cell system, wherein the flooding elimination / prevention means is a fuel gas increase means for increasing the flow rate of the fuel gas supplied to the fuel cell. The vehicle fuel cell system according to claim 2,
The vehicle fuel cell system, wherein the flooding elimination / prevention means is a cooling water temperature raising means for raising the temperature of the cooling water of the fuel cell. The vehicle fuel cell system according to claim 2,
The vehicle fuel cell system according to claim 1, wherein the flooding elimination / prevention means is a purge execution means for executing a purge for blowing off moisture using fuel gas or oxidizing gas of the fuel cell. The vehicle fuel cell system according to claim 1,
A fuel cell system for a vehicle, comprising a power source switching means for driving the vehicle with the power of the secondary battery instead of the fuel cell based on the result of the judging means. The vehicle fuel cell system according to claim 1,
The estimation means estimates the gas flow rate based on the power generation current of the fuel cell.

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