JP2007109565A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent water from flowing into a fuel circulation means without drainage from a water accumulation apparatus, at resumption of supply of fuel/oxidant for a fuel cell after suspended supply operation. <P>SOLUTION: A fuel/oxidant supply stop decision section 104 makes a decision to stop supplying at least either one of the fuel or oxidant, based on the accumulated amounts of water detected by a water accumulation amount detection means 101, the stoppage time estimated by a stoppage time estimation means, and status of a fuel cell system detected by a fuel cell operational status detection means 103; then gives a supply stop instruction to a fuel supply means 105, and a oxidant supply means 106. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fuel cell system, and more particularly to a fuel cell system with improved idle stop performance suitable for a power source of a moving body.

  In a fuel cell, a fuel gas such as hydrogen gas and an oxidizing gas containing oxygen are electrochemically reacted through an electrolyte, and electric energy is directly taken out between electrodes provided on both surfaces of the electrolyte. In particular, solid polymer fuel cells using solid polymer electrolytes are attracting attention as power sources for electric vehicles because of their low operating temperature and easy handling. That is, a fuel cell vehicle is equipped with a hydrogen storage device such as a high-pressure hydrogen tank, a liquid hydrogen tank, or a hydrogen storage alloy tank in the vehicle, and reacts by supplying hydrogen supplied therefrom and oxygen-containing air to the fuel cell. This is the ultimate clean vehicle that drives the motor connected to the drive wheels with the electric energy extracted from the fuel cell, and that the only exhaust material is water.

  By the way, in the operation region where the output of the fuel cell is small, there is a system in which power generation is stopped because power generation efficiency is low and power is supplied from a power storage device such as a secondary battery or a capacitor. In this system, it is possible to avoid an operation region where the power generation efficiency of the fuel cell is low and to improve the fuel efficiency of the fuel cell system.

For example, in the fuel cell vehicle disclosed in Patent Document 1, the hydrogen pressure at the anode inlet, the cell voltage of the fuel cell, the hydrogen of the hydrogen dilution means disposed at the anode outlet, even when the required power generation amount is a predetermined value or less. There is a condition for prohibiting the idle stop depending on the concentration or the like.
JP 2004-173450 A (page 6, FIG. 3)

  However, since the above conventional example does not consider the amount of water in the water tank as the idle stop condition, the water condensed in the fuel cell or the piping during the idle stop and when returning from the idle stop to the power generation state. As a result, the water level of the water tank rises and the operation of the fuel circulation pump is hindered.

  In particular, in-vehicle fuel cell systems, where the location of the water tank and the shape of the water distribution pipe are restricted in terms of mounting, drain water using the pressure difference between the tank pressure and atmospheric pressure. Since the hydrogen pressure and air pressure decreased, water could not be drained, and draining after the end of the idle stop had a problem that the return time from the idle stop to the power generation state was prolonged.

  In order to solve the above problems, the present invention provides a fuel cell in which an electrolyte membrane is sandwiched between a fuel electrode and an oxidant electrode, fuel supply means for supplying fuel gas to the fuel electrode, and the oxidation A fuel comprising: an oxidant supply unit that supplies an oxidant gas to the agent electrode; a water storage device that stores water as liquid water; and a water storage amount detection unit that detects the amount of water stored in the water storage device. The gist of the present invention is that the battery system includes a control device that determines the supply stop of at least one of the fuel gas and the oxidant gas based on the detection value of the water accumulation amount detection means.

  According to the present invention, it is possible to determine the supply stop of at least one of the fuel gas and the oxidant gas by setting the water amount of the water storage device to an appropriate value, and to quickly return to the power generation state without any trouble after the supply is resumed. There is an effect that can be.

  Next, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a control block diagram for explaining the outline of the first embodiment of the fuel cell system according to the present invention. The fuel cell system detects water accumulation amount detection means 101 for detecting the amount of water accumulated in the water accumulation device, stop time estimation means 102 for estimating the idle stop time when the fuel cell is under low load, and detects the state of the fuel cell system. Based on the detected value of the fuel cell state detection means 103, the detected value of the water accumulation amount detection means 101, the stop time estimated by the stop time estimation means, and the state of the fuel cell system detected by the fuel cell operating state detection means 103 A fuel / oxidant supply stop determination unit 104 that determines to stop the supply of at least one of the oxidants, a fuel supply unit 105 that supplies fuel gas to the fuel electrode of the fuel cell, and an oxidant to the oxidant electrode of the fuel cell Oxidant supply means 106 for supplying water and water transfer means 107 for draining water from the water storage device.

  FIG. 2 is a system configuration diagram showing a schematic configuration of the fuel cell system according to the present invention. The fuel cell system 1 includes, for example, a polymer electrolyte fuel cell 2. The fuel cell 2 has a structure in which a plurality of unit cells (cells) in which an electrolyte membrane 3 is sandwiched between an anode (fuel electrode) 4 and a cathode (oxidant electrode) 5 are stacked, but only the unit cell is illustrated. Hydrogen gas is supplied as fuel to the anode 4 and air is supplied as oxidant gas to the cathode 5, and the electrode reaction shown below proceeds to generate electric power.

Anode (fuel electrode): H ₂ → 2H ⁺ + 2e ⁻ (1)
Cathode (oxidant electrode): 2H ⁺ + 2e ⁻ + (1/2) O ₂ → H ₂ O (2)
Hydrogen as a fuel gas is supplied from the hydrogen tank 6 to the anode 4 through the hydrogen tank main valve 7, the pressure reducing valve 8, and the hydrogen supply valve 9. The high-pressure hydrogen supplied from the hydrogen tank 6 is mechanically reduced to a predetermined pressure by the pressure reducing valve 8 and further reduced by the hydrogen supply valve 9 so that the hydrogen pressure at the inlet of the anode 4 becomes a desired pressure. From the hydrogen tank 6 to the hydrogen supply valve 9 corresponds to the fuel supply means 105 of FIG.

  A fuel circulation path 11 is provided for circulating the fuel gas that has not been consumed at the anode from the outlet of the anode 4 to the inlet of the anode 4. The circulation pump 12 is fuel circulation means for increasing the pressure of the fuel gas in the fuel circulation path 11 and circulating it.

  The fuel circulation path 11 between the outlet of the anode 4 and the circulation pump 12 is provided with a water tank 25 that is a water accumulation device that accumulates water as liquid water. The water tank has a gas-liquid separation function of separating moisture in the anode off gas discharged from the anode 4, and prevents liquid water from flowing into the circulation pump 12. The water in the water tank 25 may be used, for example, for humidifying air supplied to the cathode 5 by a humidifier (not shown) or hydrogen supplied to the anode 4, or water formed inside the fuel cell 2. It may be used to humidify the fuel cell 2 by supplying it to the passage.

  The amount of water accumulated in the water tank 25 is detected by a water level sensor 27 (water accumulation amount detection means 101 in FIG. 1), and a detection signal is sent to the controller 30. In addition, a drain valve 26 (water moving means 107 in FIG. 1) is disposed at the bottom of the water tank 25, and the water in the water tank 25 is discharged out of the system by opening and closing the drain valve 26 under the control of the controller 30. Thus, the amount of water in the tank can be controlled.

  Air to the cathode 5 is supplied by a compressor 14 which is an oxidant supply means (106 in FIG. 1). An air pressure adjusting valve 24 is provided at the cathode outlet to control the cathode pressure.

  The power manager 15 extracts power from the fuel cell 2 and supplies power to the load device 16 or the battery 17. The battery controller 18 monitors the charge / discharge current of the battery 17 to calculate the amount of electricity stored in the battery, and transmits the amount of electricity stored to the controller 30. The voltage sensor 19 measures the voltage of each unit cell of the fuel cell 2 or each unit cell group in which a plurality of unit cells are connected in series. The controller 30 controls each actuator in the system using each sensor signal at the time of starting, stopping, and generating power of the fuel cell system.

  In order to supply air as an oxidant to the cathode 5, non-chemically reacting nitrogen permeates the electrolyte membrane 3 and accumulates in a hydrogen circulation system including the anode 4, the fuel circulation path 11 and the circulation pump 12. If the amount of nitrogen accumulated in the hydrogen circulation system increases too much, the mass density of the gas in the hydrogen circulation system increases and the gas circulation amount by the circulation pump 12 cannot be maintained, so the amount of nitrogen in the hydrogen circulation system must be managed. There is. Therefore, the gas containing nitrogen in the hydrogen circulation system is discharged to the outside by the purge valve 20 so that the circulation performance can be maintained for the amount of nitrogen present in the hydrogen circulation system. The pressure sensor 10 is a sensor that measures the pressure at the anode outlet, and the temperature sensor 21 is a sensor that measures the temperature of the gas at the anode outlet. Each detected value is input to the controller 30.

  In this embodiment, the controller 30 is composed of a CPU, a ROM, a working RAM, and a microprocessor having an input / output interface. The controller 30 executes the control program stored in the ROM, thereby controlling the entire fuel cell system and determining whether to stop the fuel / oxidant supply to the fuel cell 2 of the fuel cell system according to the present invention. It is a control device (reference numeral 104 in FIG. 1).

  Next, the operation of the controller 30 in the first embodiment will be described with reference to the control block diagram of FIG. The water accumulation amount detection unit 31 converts the water level detected by the water level sensor 27 into a water accumulation amount and outputs the water accumulation amount to the hydrogen supply / compressor stop determination unit 35.

  The stop time prediction calculation unit 32 inputs an on / off signal of the key switch 23 and a signal indicating the magnitude of the required power, and when the off signal of the key switch is input or when the required power is 0, Predicting that the stop time is long, output to the hydrogen supply / compressor stop determination unit 35. The stop time prediction calculation unit 32 receives a signal indicating the amount of power stored in the battery 17 from the battery controller 18 and also receives a signal indicating the amount of power consumption of the vehicle from a vehicle control computer (not shown). The time during which power can be supplied from the battery 17 is calculated and output to the hydrogen supply / compressor stop determination unit 35.

  The stoppable prediction calculation unit 33 inputs a vehicle speed signal detected by a vehicle speed sensor (not shown), an accelerator operation amount signal from an accelerator sensor (not shown), and a storage amount of the battery 17 from the battery controller 18. When the accelerator operation amount is 0, the vehicle speed is equal to or lower than the predetermined speed, and the charged amount is equal to or higher than the predetermined amount, it is predicted that there is a high possibility that the vehicle can be idle-stopped. Output to the stop determination unit 35.

  The fuel cell system state quantity detection unit 34 inputs detection values of the fuel cell system state such as the pressure sensor 10, the temperature sensor 21, and a fuel cell coolant temperature sensor (not shown), and outputs them to the hydrogen supply / compressor stop determination unit 35. To do.

  The hydrogen supply / compressor stop determination unit 35 includes a water accumulation amount from the water accumulation amount detection unit 31, a stop time prediction value from the stop time prediction calculation unit 32, a stop possibility from the stop possibility prediction calculation unit 33, and a fuel cell. Based on the fuel cell system state quantity from the system state quantity detection unit 34, it is determined whether or not to perform an idle stop that stops the hydrogen supply and the compressor for a short time.

  The hydrogen supply valve control unit 36 performs a closing operation of the hydrogen supply valve 9 at the time of idling stop according to an instruction from the hydrogen supply / compressor stop determination unit 35.

  The compressor control unit 37 performs a stop operation of the compressor 14 at the time of idling stop according to an instruction from the hydrogen supply / compressor stop determination unit 35.

  During normal operation, the drain valve control unit 38 opens the drain valve 26 based on the water accumulation amount of the water tank 25 detected by the water accumulation amount detection unit 31 when the water accumulation amount exceeds the drainage start water flow. While the water in the water tank 25 is drained, the drain valve is closed and the drainage is stopped when the accumulated amount of water becomes equal to or less than the drainage stop water amount less than the drainage start water amount.

  When the stop time prediction calculation unit 32 notifies the hydrogen supply / compressor stop determination unit 35 of the prediction of a long-term stop, the power generation amount control unit 39 is less than a predetermined water amount that exceeds the drain stop water amount. For example, the amount of power generated by the fuel cell 2 is increased to increase the amount of water generated by power generation, and the amount of water required for starting the fuel cell system is ensured even if the inside of the fuel cell 2 dries after a long stop.

  During normal power generation, the circulation pump control unit 40 controls driving of the circulation pump 12 according to, for example, the hydrogen supply amount, and drives the circulation pump 12 according to an instruction from the hydrogen supply / compressor stop determination unit 35, so that the fuel cell 2. The liquid water in the anode 4 or the fuel circulation path 11 is transported to the water tank 25.

  Next, processing contents of the controller in the first embodiment will be described with reference to the control flowchart of FIG. The following flowchart is called and executed when an idle stop condition other than the amount of water in the water tank 25 is satisfied or when the key switch 23 is switched from the on state to the off state. The idle stop conditions other than the amount of water are, for example, that the temperature of the fuel cell 2 is equal to or higher than a predetermined temperature and the warm-up is completed, the required power for the fuel cell system exceeds 0 and is equal to or lower than a predetermined value, That is, all the conditions that the storage amount of the battery 17 is equal to or greater than a predetermined value are satisfied.

  First, in step 402 of FIG. 4 (hereinafter, step is abbreviated as S), the water level sensor 27 detects the water level in the water tank 25 and converts the water level into the amount of water. Next, in S403, the length of the stop time of the fuel cell system is determined. For this, if an off signal is input from the key switch 23 or the required power to the fuel cell system is 0, it is determined that the time is long, and otherwise it is determined that the time is short.

  When it is determined in S403 that the time is long, the process proceeds to S404, and when it is determined that the time is short in S403, the process proceeds to S410. In S404, the water amount threshold value determined to stop the supply of fuel and oxidant is set to the long-time threshold value (first predetermined water amount), and the process proceeds to S405. This long-time threshold value is a value that is less than the drainage start water amount that starts drainage by opening the drain valve 26 of the water tank 25 and exceeds the drainage stop water amount that closes the drain valve 26 and stops drainage during normal operation. . The purpose of setting such a long-time threshold is that when the fuel cell system is stopped for a long time, the inside of the fuel cell, the humidifier, and the like are dried, so that a larger amount of water is required at the time of restart than when the fuel cell system is stopped for a short time. It is to do.

  In S405, the water level detected by the water level sensor 27 is converted into a water amount, the water amount is compared with a long-time threshold value, and it is determined whether or not the water amount is equal to or greater than the long-time threshold value. It is determined whether or not the stop is permitted. If the amount of water is greater than or equal to the long-time threshold, the process proceeds to S406. In S406, the hydrogen supply valve 9 is closed to stop the hydrogen supply. In S407, the compressor 14 is stopped to stop the air supply, and the process is terminated by entering the stop state.

  If it is determined in S405 that the water amount is not equal to or longer than the long-time threshold value, the flow proceeds to S408, the flow rate of hydrogen supplied from the hydrogen supply valve 9 is increased so that the power generation amount of the fuel cell 2 is increased, and the compressor 14 is rotated. The speed is increased to instruct the power manager 15 to increase the current drawn from the fuel cell 2. Thereby, the generated water in the fuel cell 2 increases. Next, in S409, the water level sensor 27 detects the water level in the water tank 25, converts the water level into the amount of water, and returns to S405.

  In S410, the water amount threshold value determined to stop the fuel and oxidant supply is set to the short time threshold value (second predetermined water amount), and the process proceeds to S411. This short-time threshold value is a value that is less than the drainage start water amount that starts drainage by opening the drain valve 26 of the water tank 25 during normal operation, and exceeds the drainage stop water amount that stops drainage by closing the drain valve 26. In addition, the value is less than the long time threshold set in S404. Further, the short time threshold value may be corrected by the fuel cell temperature. In this correction, the higher the fuel cell temperature, the higher the vapor pressure of the generated water, and the greater the amount of water that can condense during idle stop, so the higher the fuel cell temperature, the shorter the threshold value for short time. Correct so that becomes smaller. This correction may be changed so that the short-time threshold value decreases as the temperature difference between the fuel cell temperature and the outside air temperature increases.

  By setting such a short-time threshold value, even if liquid water condensed in the anode 4 or the fuel circulation path 11 flows into the water tank 25 during idle stop, the drainage start water level is not exceeded and the idle water level is not exceeded. Even when the driving of the circulation pump 12 is resumed immediately without draining from the water tank 25 at the restart after the stop, the water overflowing from the water tank 25 flows into the circulation pump 12 and inhibits the circulation of the fuel gas. There is an effect that things disappear.

  In S411, the water level detected by the water level sensor 27 is converted into a water amount, the water amount is compared with the short time threshold value, and it is determined whether or not the water amount is less than the short time threshold value. It is determined whether or not the stop is permitted. If the amount of water is less than the short-time threshold, the process proceeds to S412. If the amount of water is not less than the short-time threshold, the process returns to S402.

  In S412, the hydrogen supply valve 9 is closed to stop the hydrogen supply. In S413, the compressor 14 is stopped to stop the air supply, and the process is ended by entering the idle stop state. In the idle stop state, for example, the required generated power, the stored amount of the battery 17, the fuel cell temperature, and the like are monitored by a control flow (not shown). When any of the battery temperature is detected below a predetermined value, control is performed so that the normal power generation state is restored.

  Furthermore, the controller 30 may monitor the water level sensor 27 during idle stop. In particular, when the outside air temperature is low, such as in a cold region, even if the amount of water in the water tank 25 detected by the water level sensor 27 during idle stop may reach the drainage start water amount, the controller 30 interrupts idle stop and generates power. By controlling to return to the state, the water tank can be drained, and the operation of the circulation pump is not hindered by the water overflowing from the water tank.

  Next, a second embodiment of the fuel cell system according to the present invention will be described. The system configuration diagram and control block diagram of the second embodiment are the same as the configuration of the first embodiment shown in FIGS. The feature of the fuel cell system of this embodiment is that when the hydrogen supply / compressor stop conditions other than the water amount in the water tank are satisfied and only the water tank water amount condition is not satisfied, the water amount reaches the drainage start water amount during normal operation. Even if not, the drain valve 26 is opened to drain from the water tank 25.

  Next, processing contents of the controller in the second embodiment will be described with reference to the control flowchart of FIG. First, in S502 of FIG. 5, the state quantity of the fuel cell system is measured by each sensor of the fuel cell system. Next, in S503, it is determined whether conditions for hydrogen supply and compressor stop other than the amount of water in the water tank 25 are satisfied. The conditions for hydrogen supply / compressor stoppage other than the amount of water are, for example, that the temperature of the fuel cell 2 is equal to or higher than a predetermined temperature and the warm-up is completed, and the required power for the fuel cell system exceeds 0 and is lower than a predetermined value. That is, all the conditions that the amount of power stored in the battery 17 is equal to or greater than a predetermined value are satisfied.

  If the condition is not satisfied in S503, the process returns to S502. If the condition is satisfied in S503, the process proceeds to S504, where the water level sensor 27 detects the water level in the water tank 25, and converts the water level into the amount of water. Next, in S505, it is determined whether or not the amount of water measured in S504 is less than a threshold (second predetermined value) for determining that the supply of fuel and oxidant is to be stopped. It is determined whether or not a stop condition is satisfied. This threshold value is a value that is less than the drainage start water amount that starts drainage by opening the drain valve 26 of the water tank 25 during normal operation, and that exceeds the drainage stop water amount that stops drainage by closing the drain valve 26.

  If it is determined in S505 that the amount of water is less than the threshold value, the process proceeds to S506, where the hydrogen supply valve 9 is closed and the hydrogen supply is stopped. In S413, the compressor 14 is stopped and the air supply is stopped to enter the idle stop state. The process is terminated by entering. In the idle stop state, for example, the required generated power, the stored amount of the battery 17, the fuel cell temperature, and the like are monitored by a control flow (not shown). When any of the battery temperature is detected below a predetermined value, control is performed so that the normal power generation state is restored.

  If it is determined in S505 that the amount of water is not less than the threshold value, the flow proceeds to S508, the drain valve 26 is opened, and water is discharged from the water tank 25 to the outside. Next, in S509, the water level in the water tank 25 is detected by the water level sensor 27, and the water level is converted into the amount of water. Next, in S510, it is determined whether or not the amount of water measured in S509 is less than a threshold (second predetermined value) for determining that the supply of fuel and oxidant is to be stopped, whereby the hydrogen supply / compressor relating to the amount of water in the water tank 25 is determined. It is determined whether or not a stop condition is satisfied. If it is determined in S510 that the amount of water is less than the threshold, the process proceeds to S511, the drain valve 26 is closed, and the process proceeds to S506. If the amount of water is not less than the threshold value in S510, the process returns to S508 to continue draining.

  According to the embodiment described above, when the idle stop condition other than the water amount in the water tank is satisfied and the water amount condition is not satisfied, the water tank is drained even if it does not reach the drainage start water amount. There is an effect that it is possible to quickly move to idle stop.

  Next, a third embodiment of the fuel cell system according to the present invention will be described. The system configuration diagram and control block diagram of the third embodiment are the same as the configuration of the first embodiment shown in FIGS.

  In FIG. 3, the stoppable prediction calculation unit 33 in the present embodiment includes a vehicle speed signal detected by a vehicle speed sensor (not shown), an accelerator operation amount signal from an accelerator sensor (not shown), and a storage amount of the battery 17 from the battery controller 18. Enter each. When the accelerator operation amount is 0, the vehicle speed is equal to or lower than the predetermined speed, and the charged amount is equal to or higher than the predetermined amount, it is predicted that there is a high possibility that the vehicle can be idle-stopped. Output to the stop determination unit 35.

  Then, the drain valve control unit 38, in response to an instruction from the hydrogen supply / compressor stop determination unit 35, predicts water in advance even if the water accumulation amount in the water tank 25 does not reach the drainage start water amount when the idle stop is predicted. The amount of water in the tank can be made less than the threshold value, and when an idle stop condition other than the amount of water is satisfied, it is possible to quickly shift to the idle stop.

  Next, processing contents of the controller in the third embodiment will be described with reference to the control flowchart of FIG. First, in S602 of FIG. 6, the speed signal of the moving body is detected from the vehicle speed sensor. Next, in S603, the operation status of the mobile driver is detected. The operation status includes an accelerator operation amount, a brake operation amount, and a shift position of the transmission if provided.

  In step S604, the storage amount of the battery 17 is read from the battery controller 18. In step S606, it is determined whether or not the idle stop in which the hydrogen supply and the compressor stop are performed for a short time is large or small. For example, when the accelerator operation amount is 0, the vehicle speed is a predetermined speed (for example, 20 km / h) or less, and the storage amount is not less than a predetermined amount (for example, the storage amount that can cover the current vehicle power consumption for about 5 minutes), It is determined that there is a high possibility of stopping in a state where idling can be stopped, and otherwise, it is determined that it is small.

  If it is determined in S605 that the possibility of stopping is small, the process returns to S602. When it is determined in S605 that the possibility of stopping is high, the process proceeds to S606. In S606, the detection value of the water level sensor 27 is read. In S607, it is determined whether or not the water amount is less than a threshold value of the water amount that can be idle-stopped. If the amount of water is less than the threshold of the amount of water that can be idle-stopped, the condition of the amount of water is satisfied, and the process is terminated without doing anything.

  If it is determined in S607 that the amount of water is not less than the threshold value of the amount of water that can be idle-stopped, the processing in S608 and subsequent steps is performed to reduce the amount of water in the water tank 25 in order to establish the water amount condition in advance. In S608, the drain valve 26 is opened, and the detection value of the water level sensor 27 is read in S609. In S610, it is determined whether or not the water amount is less than a threshold value of the water amount that can be idle-stopped. If the amount of water is not less than the threshold value of the amount of water that can be idle-stopped, the flow returns to S608 to continue draining. If the amount of water is less than the threshold of the amount of water that can be idle-stopped, the condition of the amount of water has been satisfied in advance, and the process is terminated.

  Next, a fourth embodiment of the fuel cell system according to the present invention will be described. The system configuration diagram and control block diagram of the fourth embodiment are the same as the configuration of the first embodiment shown in FIGS.

  As in the third embodiment, the feature of the present embodiment is that when the possibility of idling stop is determined to be large, if the amount of water in the water tank is not less than the threshold of the amount of water that can be idle stopped, the power generation amount is increased. The number of generated water is increased by increasing the number of rotations of the circulation pump, and liquid water condensed from the anode 4 and the fuel circulation path 11 is collected, so that the amount of water in the water tank reaches the amount of drainage starting water during normal operation. In other words, drainage is performed under normal operation control. As a result, when an idle stop is predicted in advance, the amount of water in the water tank can be reduced below the threshold for the amount of water that can be idle stopped.

  Next, processing contents of the controller in the fourth embodiment will be described with reference to the control flowchart of FIG. First, in S702 of FIG. 7, the speed signal of the moving body is detected from the vehicle speed sensor. Next, in S703, the operation status of the mobile driver is detected. The operation status includes an accelerator operation amount, a brake operation amount, and a shift position of the transmission if provided.

  In step S704, the storage amount of the battery 17 is read from the battery controller 18. In step S706, a determination is made as to whether or not the possibility of idling stop in which hydrogen supply and compressor stop for a short time are performed. For example, when the accelerator operation amount is 0, the vehicle speed is a predetermined speed (for example, 20 km / h) or less, and the storage amount is not less than a predetermined amount (for example, the storage amount that can cover the current vehicle power consumption for about 5 minutes), It is determined that there is a high possibility of stopping in a state where idling can be stopped, and otherwise, it is determined that it is small.

  If it is determined in S705 that the possibility of stopping is small, the process returns to S702. When it is determined in S705 that the possibility of stopping is high, the process proceeds to S706. In S706, the detection value of the water level sensor 27 is read, and in S707, it is determined whether or not the water amount is less than a threshold value of the water amount that can be idle-stopped. If the amount of water is less than the threshold of the amount of water that can be idle-stopped, the condition of the amount of water is satisfied, and the process is terminated without doing anything.

  If it is determined in S707 that the amount of water is not less than the threshold value of the amount of water that can be idle-stopped, the processing of S708 and subsequent steps is performed to reduce the amount of water in the water tank 25 in order to establish the water amount condition in advance. In S708, the flow rate of hydrogen supplied from the hydrogen supply valve 9 is increased so as to increase the power generation amount of the fuel cell 2, and the rotational speed of the compressor 14 is increased so that the current extracted from the fuel cell 2 to the power manager 15 is increased. Instruct to increase. Thereby, the generated water in the fuel cell 2 increases.

  Next, in S709, the rotational speed of the circulation pump 12 is increased, and liquid water is effectively recovered from the anode 4 and the fuel circulation path 11 to the water tank 25. In S710, the detection value of the water level sensor 27 is read. In S711, it is determined whether or not the water amount is less than a threshold value of the water amount that can be idle-stopped. If the amount of water is not less than the threshold of the amount of water that can be idle-stopped, the process returns to S708 and continues to increase the amount of power generation. If the amount of water is less than the threshold of the amount of water that can be idle-stopped, the condition of the amount of water has been satisfied in advance, and the process is terminated.

  Next, a fifth embodiment of the fuel cell system according to the present invention will be described. The control block diagram of the fifth embodiment is the same as the configuration of the first embodiment shown in FIGS.

  FIG. 8 is a system configuration diagram of the fuel cell system in the present embodiment. The fuel cell system of the present embodiment supplies the cathode 5 with the oxidant from the compressed oxygen or high-pressure air stored in the oxidant supply source 14 to the cathode 5 and circulates the cathode off-gas discharged from the cathode 5 to the cathode again. The oxidant circulation path 28 and the oxidant circulation pump 29 are provided, and the water tank 25 is characterized by being provided in the oxidant circulation path 28. Other configurations are the same as the system configuration diagram applied to the first to fourth embodiments illustrated in FIG.

  Even in such a configuration in which the water tank 25 having a gas-liquid separation function is provided in the oxidant circulation path 28, the same effects as those of the first to fourth embodiments are achieved by performing the control as described in the first to fourth embodiments. Is obtained.

  While preferred embodiments have been described above, they are not intended to limit the invention. For example, in each of the embodiments described above, both the hydrogen gas (fuel) supply and the air (oxidant) supply are stopped in the idle stop. However, when one of the hydrogen gas supply or the air supply is stopped. Needless to say, the present invention is applicable.

It is a principal part block diagram of the fuel cell system which concerns on this invention. 1 is a system configuration diagram illustrating an overall configuration of Embodiment 1. FIG. FIG. 3 is a control block diagram illustrating the control device according to the first embodiment. 3 is a control flowchart of the first embodiment. 6 is a control flowchart of Embodiment 2. 10 is a control flowchart of Embodiment 3. 10 is a control flowchart of Embodiment 4. FIG. 10 is a system configuration diagram of a fifth embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 ... Water accumulation amount detection means 102 ... Stop time estimation means 103 ... Fuel cell operation state detection means 104 ... Fuel / oxidant supply stop judgment part 105 ... Fuel supply means 106 ... Oxidant supply means 107 ... Water transfer means

Claims (14)

A fuel cell having an electrolyte membrane sandwiched between a fuel electrode and an oxidant electrode;
Fuel supply means for supplying fuel gas to the fuel electrode;
An oxidant supply means for supplying an oxidant gas to the oxidant electrode;
A water storage device for storing water as liquid water;
Water accumulation amount detecting means for detecting the amount of water accumulated in the water accumulation device;
In a fuel cell system comprising:
A fuel cell system, comprising: a control device that determines a supply stop of at least one of fuel gas and oxidant gas based on a detection value of the water accumulation amount detection means. A fuel circulation path for recirculating unreacted fuel gas discharged from the fuel electrode to the fuel electrode;
Fuel circulation means for circulating the fuel gas in the fuel circulation path from the fuel electrode outlet to the fuel electrode inlet,
The fuel cell system according to claim 1, wherein the water storage device is disposed in the fuel circulation path. Water moving means for starting drainage from the water accumulation device when the detection value of the water accumulation amount detection means exceeds the drainage start water quantity, and stopping drainage when the drainage stop water quantity is less than the drainage start water quantity, ,
A stop time estimating means for estimating a duration of supply stop of at least one of the fuel gas and the oxidant gas,
When the time estimated by the stop time estimation means is longer than a predetermined time, the detected value of the water accumulation amount detection means is greater than or equal to a first predetermined water amount that exceeds the drainage stop water amount and less than the drainage start water amount. The fuel cell system according to claim 2, wherein the fuel cell system is a condition for stopping supply of at least one of the fuel gas and the oxidant gas.   If the detection value of the water accumulation amount detection means is less than the first predetermined water amount when the time estimated by the stop time estimation means is longer than a predetermined time, the power generation condition of the fuel cell is set to the value of the water accumulation device. The fuel cell system according to claim 3, wherein the fuel cell system is set so that the amount of water increases. When the time estimated by the stop time estimating means is longer than a predetermined time,
5. The fuel cell system according to claim 3, wherein the required generated power for the fuel cell system is 0, or when there is a generation stop request for the fuel cell system. 6. Water moving means for starting drainage from the water accumulation device when the detection value of the water accumulation amount detection means exceeds the drainage start water quantity, and stopping drainage when the drainage stop water quantity is less than the drainage start water quantity, ,
A stop time estimating means for estimating a duration of supply stop of at least one of the fuel gas and the oxidant gas,
When the time estimated by the stop time estimating means is shorter than a predetermined time, the detected value of the water accumulation amount detecting means is less than a second predetermined water amount that exceeds the drain stop water amount and less than the drain stop water amount. The fuel cell system according to claim 2, wherein the fuel cell system is a condition for stopping supply of at least one of the fuel gas and the oxidant gas.   When the time estimated by the stop time estimating means is shorter than a predetermined time and the detected value of the water accumulation amount detecting means is equal to or greater than the second predetermined water amount, the water moving means causes the water accumulation device to drain. The fuel cell system according to claim 6, wherein the fuel cell system is less than the second predetermined amount of water. Comprising stoppable prediction means for predicting that the supply stop condition of at least one of the fuel gas and the oxidant gas other than the water amount of the water storage device is satisfied,
8. The fuel cell system according to claim 7, wherein when the stoppable prediction unit predicts that stoppage is possible, the water storage unit previously sets the amount of water stored in the water storage device to be less than the second predetermined amount of water. 9. . The fuel cell supplies power to a power source of a moving body,
The fuel cell system according to claim 8, wherein the stoppable prediction unit predicts the stoppable based on a speed of a moving body and a driving operation state of the moving body. When the generated power of the fuel cell is insufficient, a power storage device that supplies power to the load device of the fuel cell is provided,
The fuel cell system according to claim 8, wherein the stoppable prediction unit predicts the stoppable based on a storage amount of the power storage device. Comprising temperature detecting means for detecting the temperature of the fuel cell;
11. The fuel cell system according to claim 6, wherein the second predetermined water amount is corrected to be smaller as the temperature detected by the temperature detection unit is higher. Water moving means for starting drainage from the water accumulation device when the detection value of the water accumulation amount detection means exceeds the drainage start water quantity, and stopping drainage when the drainage stop water quantity is less than the drainage start water quantity, ,
A stop time estimating means for estimating a duration of supply stop of at least one of the fuel gas and the oxidant gas,
The fuel circulation unit is operated to transport water in the fuel electrode and the fuel circulation path to the water storage device when the time estimated by the stop time estimation unit is shorter than a predetermined time. Item 3. The fuel cell system according to Item 2. When the generated power of the fuel cell is insufficient, a power storage device that supplies power to the load device of the fuel cell is provided,
2. The fuel cell system according to claim 1, wherein the control device stops supply of at least one of the fuel gas and the oxidant gas when the required power can be supplied from the power storage device.   When the water accumulation amount detected by the water accumulation amount detection means reaches the drainage start water amount while the supply of at least one of the fuel gas and the oxidant gas is stopped, the control device 4. The fuel cell system according to claim 3, wherein control is performed so as to interrupt the supply stop of at least one of the gas and return to the power generation state.

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