JP2007265653A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system with improved acoustic vibration performance at a power generation state after return from idling stoppage. <P>SOLUTION: The fuel cell system 102 generates power by electrochemical reaction of fuel gas and oxidant gas. A battery 107, while being charged by generated power of the fuel cell system 102, supplies power in case generated power of a fuel cell is in short supply. A controller 109 carries out an idling stop control, in which it temporarily stops supply of at least oxidant gas to the fuel cell at its low load to temporarily stop generation of power by the fuel cell to shift it into an idling stoppage state, while, on the other hand, it restarts power generation by releasing the idling stoppage state to restart supply of at least oxidant gas. Further, the controller 109, after it releases the idling stoppage state to shift to a power generation state, restrains charging of the battery 107 as compared with a norma operation state. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel cell system that performs idling stop, and more particularly, to a fuel cell system that has improved acoustic vibration characteristics after returning from an idling stop to a power generation state.

  In order to improve the fuel efficiency of the fuel cell system, there is a fuel cell system that performs idling stop that temporarily stops power generation when the load is low. In such a system, a power storage device charged from a fuel cell is provided, and when the load is low, power generation of the fuel cell is stopped and power is supplied from the power storage device to the load device. As a result, fuel cell power generation at a low load with relatively low power generation efficiency can be avoided, and the fuel efficiency of the fuel cell system can be improved.

  Such an idling stop is particularly effective for a fuel cell system for vehicles with a wide load range. For example, an idle control device for a fuel cell vehicle described in Patent Document 1 is known. This control device has a function of stopping the power generation of the fuel cell by stopping the compressor when the state of the vehicle is determined to be a predetermined idle state. When the remaining capacity of the capacitor, which is a power storage device, falls below a predetermined value during idle stop, the compressor is driven by the power of the capacitor to restart the fuel cell, and the restarted fuel cell is operated as normal. The capacitor is charged by generating power in an operation region where the power generation efficiency is better than that in the region.

When the idling stop state is canceled and the fuel cell is brought into a power generation state, the fuel cell system is controlled so as to charge the capacitor a lot in preparation for the next idling stop.
Japanese Unexamined Patent Publication No. 2004-056868 (5th page, FIG. 2)

  However, in the above-described prior art, after the idling stop state is canceled and power generation is resumed, the air compressor is driven more than the normal operation state by the amount charged to the power storage device. Therefore, when the conventional idling stop is cancelled, the air compressor stops and shifts from a very quiet state to a state where the air compressor driving sound is larger than usual. As a result, the acoustic vibration performance is deteriorated, and there is a problem that the driver feels uncomfortable or uncomfortable.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a fuel cell system having improved acoustic vibration performance in a power generation state after returning from an idling stop.

  In order to achieve the above object, the present invention provides a fuel cell that generates power by an electrochemical reaction between a fuel gas and an oxidant gas, and is charged with the generated power of the fuel cell, while the generated power of the fuel cell is Power storage means for supplying power in the event of shortage, and temporarily stopping the supply of at least oxidant gas to the fuel cell, temporarily stopping power generation of the fuel cell and shifting to an idling stop state, while idling An idling stop control means for releasing the stop state and restarting at least the supply of the oxidant gas to resume power generation, and charging for charging the power storage means by increasing the power generation amount of the fuel cell according to the power storage amount of the power storage means And the charge control means cancels the idling stop state and shifts to the power generation state, and then transfers the charge control means to the power storage means. And summarized in that the suppressed than during normal operation the charging.

  According to the present invention having the above-described configuration, after the idling stop is returned, charging to the power storage means is suppressed from that during normal operation, so that the amount of power generated by the fuel cell can be suppressed. In order to suppress the supply amount of gas, noise generated by an air compressor or the like that supplies oxidant gas is reduced.

  The suppression of charging to the power storage means from the normal time includes delaying the start of charging, limiting the charging current to be smaller than normal time, and limiting the increase rate of the charging current to be small. As a result, the user who is accustomed to the silence during idling stop can suppress the acoustic vibration associated with the start of the supply of the oxidant gas after the idling stop is released, and can relieve the sense of incongruity.

  According to the present invention, after returning from the idling stop, the remaining amount of the power storage means is originally low, so that the amount of power generated by the fuel cell increases in order to charge the power storage means earlier, and air is accordingly generated. The compressor speed increases, but charging of the power storage means is suppressed, so the speed of the air compressor is reduced and the noise level is also reduced, giving the driver an uncomfortable feeling of silence during idling stop. And the effect of reducing discomfort.

  Hereinafter, a fuel cell vehicle to which the present invention is applied and a control method thereof will be described in detail with reference to the drawings.

[Description of fuel cell vehicle]
FIG. 1 is a diagram showing a basic configuration of a fuel cell vehicle equipped with a fuel cell system according to the present invention, and FIG. 2 is a diagram showing a configuration example of a fuel cell system to which the present invention is applied.

  In FIG. 1, a fuel cell vehicle 101 is a vehicle in which a fuel cell system 102 is mounted as a drive power source, and further includes an inverter 103, a drive motor 104, drive wheels 105, a vehicle speed sensor 106, a battery 107, a relay 108, and A controller 109 is provided. The fuel cell vehicle 101 also includes a shift position sensor 111 that detects the position of the shift lever, a brake sensor 112 that detects the presence or absence of a brake operation, and an accelerator sensor 113 that detects an accelerator operation amount.

  In the fuel cell system 102, the fuel gas hydrogen supplied to the fuel cell system 102 and the oxidant gas air pressure and flow rate so that the power consumed by the drive motor 104 and the power required for charging the battery 107 can be generated. Etc. are controlled by a pressure regulating valve, a compressor and the like shown in FIG.

  The inverter 103 converts the direct current power generated by the fuel cell system 102 into alternating current power, and controls the drive motor 104 so as to obtain an output torque that drives the drive motor 104 instructed by the controller 109.

  The drive wheels 105 are mechanically connected to the drive motor 104, and the drive torque obtained by the drive motor 104 is transmitted to generate a drive force to drive the vehicle. The vehicle speed sensor 106 detects the rotational speed of the drive wheel 105. The microphone 116 converts sound in the passenger compartment into an electrical signal. The controller 109 calculates a value related to the noise level in the vehicle interior based on the electrical signal from the microphone 116.

  The battery 107 supplies power to the drive motor 104 and the pressure control valves and compressors of auxiliary equipment required for generating power by the fuel cell system 102 when power is not supplied from the fuel cell system 102, such as when idling of the vehicle is stopped. Supply. The battery 107 is provided with a voltage sensor 114 for detecting the voltage of the battery 107 and a current sensor 115 for detecting a current. Based on the voltage and current detected by the voltage sensor 114 and the current sensor 115, the controller 109 is provided. Estimates the amount of charge (SOC) of the battery 107.

  The relay 108 connects / disconnects the fuel cell system 102 and the load based on a command from the controller 109.

  The controller 109 functions as a control center that controls the operation of the fuel cell vehicle 101, and is provided with resources such as a CPU, a storage device, and an input / output device necessary for a computer that controls various operation processes based on a program. It is realized by a computer or the like. The controller 109 reads signals from the sensors in the vehicle and sensors (not shown) that collect information necessary for driving the fuel cell vehicle that cannot be obtained by these sensors. Based on the control logic (program) possessed, a command is sent to each component of the vehicle, and the vehicle operation / idling stop control and charge control to the battery as power storage means, which will be described below, Control and control all operations required for stop operation.

[Description of fuel cell PP]
Next, the fuel cell system 102 will be described with reference to FIG. In FIG. 2, the fuel cell system 102 includes a fuel cell stack 201 that generates power, a hydrogen supply system that supplies hydrogen (or hydrogen-rich gas) as a fuel gas to the fuel cell stack 201, and a fuel cell stack 201. And an air supply system for supplying air containing oxygen which is an oxidant gas.

  In the fuel cell stack 201, a power generation cell in which a hydrogen electrode to which hydrogen is supplied and an air electrode to which oxygen (air) is supplied is stacked on both sides of an electrolyte / electrode catalyst composite is stacked in a multistage manner. A power generation unit that converts chemical energy into electrical energy through an electrochemical reaction is configured.

  At the hydrogen electrode of the fuel cell stack 201, when hydrogen is supplied, it is dissociated into hydrogen ions and electrons, the hydrogen ions pass through the electrolyte, the electrons generate electric power through an external circuit, and move to the air electrode. At the air electrode, oxygen in the supplied air reacts with the hydrogen ions and electrons to generate water, which is discharged to the outside.

  As the electrolyte of the fuel cell stack 201, for example, a solid polymer electrolyte is used in consideration of high energy density, low cost, light weight, and the like. The solid polymer electrolyte is made of an ion (proton) conductive polymer film such as a fluororesin ion exchange membrane, and functions as an ion conductive electrolyte when saturated with water.

  The hydrogen supply system reduces the pressure of the high pressure hydrogen gas supplied from the high pressure hydrogen tank 202, the main valve 203, and the high pressure hydrogen tank 202 as hydrogen supply means to the operating pressure of the fuel cell stack 201 as a hydrogen supply means. A hydrogen pressure regulating valve 204 to be adjusted, a hydrogen circulation pump 208 for circulating the hydrogen off-gas through the hydrogen circulation path 207 in order to return the hydrogen off-gas discharged from the fuel cell stack 201 to the inlet side of the fuel cell stack 201 via the ejector 205, and A hydrogen supply path 206 serving as a hydrogen electrode path is provided.

  Hydrogen gas supplied from the high-pressure hydrogen tank 202 is sent to the hydrogen supply path 206 through the hydrogen pressure regulating valve 204 and supplied to the hydrogen electrode of the fuel cell stack 201. At this time, the hydrogen pressure regulating valve 204 adjusts the pressure of the supplied hydrogen gas so that the pressure in the hydrogen electrode and the hydrogen electrode passage of the fuel cell stack 201 becomes a pressure corresponding to the load.

  In the fuel cell stack 201, not all of the supplied hydrogen gas is consumed, and the hydrogen off-gas discharged from the fuel cell stack 201 without being consumed is circulated by the hydrogen circulation pump 208 through the hydrogen circulation path 207. Then, it is mixed with hydrogen gas newly supplied by the ejector 205 and supplied again to the hydrogen electrode of the fuel cell stack 201. Thereby, the stoichiometric ratio (supply flow rate / consumption flow rate) of hydrogen can be 1 or more, and the cell voltage is stabilized.

  A purge valve 210 and a purge pipe 211 are provided on the outlet side of the fuel cell stack 201 in the hydrogen supply system. The purge valve 210 is normally closed, and is opened when a drop in the cell voltage due to water clogging of the fuel cell stack 201 or accumulation of inert gas is detected. Impurities, nitrogen, and the like are accumulated by circulating hydrogen gas in the hydrogen circulation path 207, which may reduce the partial pressure of hydrogen and reduce the power generation efficiency of the fuel cell stack 201. Therefore, a purge valve 210 and a purge pipe 211 are provided on the outlet side of the fuel cell stack 201, and impurities and nitrogen are removed from the hydrogen circulation path 207 by opening the purge valve 210 and performing hydrogen purge as necessary. I can do it.

  The air supply system includes an air compressor 212 and an air pressure regulating valve 216 as air supply means, an air supply pipe 214 serving as an air supply passage to the air electrode, and an exhaust pipe 215 for discharging used air at the air electrode. ing.

  The air compressor 212 feeds air to the air electrode of the fuel cell stack 201. For example, air compressed by motor driving is supplied to the air electrode of the fuel cell stack 201 through the air supply pipe 214. The air compressor 212 is provided with a tachometer 213 that detects the rotation speed of the compressor.

  The air pressure regulating valve 216 adjusts the pressure of the air supplied to the fuel cell stack 201 by the air compressor 212, and is provided in the exhaust pipe 215 on the outlet side of the air electrode of the fuel cell stack 201. The air pressure regulating valve 216 adjusts the pressure of air supplied by the air compressor 212 so that the pressure in the air electrode and the air electrode passage of the fuel cell stack 201 becomes a pressure corresponding to the load.

  Oxygen that has not been consumed in the fuel cell stack 201 and other components in the air are discharged from the fuel cell stack 201 through the exhaust pipe 215 and the air pressure regulating valve 216.

  The above-described fuel cell stack 201 using the solid polymer electrolyte membrane has a relatively low proper operating temperature of around 80 ° C., and needs to be cooled when overheated. For this reason, a cooling mechanism (not shown) that normally cools the fuel cell stack 201 by circulating cooling water in the fuel cell stack 201 and maintains the fuel cell stack 201 at an optimum temperature is provided.

[Description of idling stop]
The system control unit 218 functions as a control center that controls the operation of the fuel cell system 102, and includes resources such as a CPU, a storage device, and an input / output device necessary for a computer that controls various operation processes based on a program. For example, it is realized by a microcomputer or the like, for example, as a partial function of the controller 109 shown in FIG.

  The system controller 218 reads signals from the sensors in the fuel cell system 102 and sensors (not shown) that collect information necessary for operation of the fuel cell system 102 that cannot be obtained by these sensors. A command is sent to each component of the fuel cell system 102 based on the read signal and the control logic (program) stored in advance.

  In addition, the system control unit 218 temporarily stops the supply of at least the oxidant gas to the fuel cell, temporarily stops the power generation of the fuel cell stack 201, and shifts to the idling stop state. An idling stop control unit that releases and restarts at least the supply of the oxidant gas to restart power generation, and a charge control unit that charges the battery 107 by increasing the power generation amount of the fuel cell stack 201 according to the amount of power stored in the battery 107. Also, the system control unit 218 performs control to suppress charging of the battery 107 from that during normal operation after the idling stop state is canceled and the state is shifted to the power generation state.

  The operation of shifting the fuel cell system 102 to the idle stop state is executed according to the procedure shown in the flowchart of FIG.

  In FIG. 3, first, in step (hereinafter abbreviated as S) 11, first, the hydrogen pressure regulating valve 204 is closed to stop the supply of hydrogen of fuel gas, then the purge valve 210 is closed in S12, and the hydrogen circulation pump in S13. The driving of 208 is stopped. Next, in S14, the driving of the air compressor 212 is stopped to stop the supply of air, and in S15, the driving of the cooling water pump is stopped. Thereby, the power generation of the fuel cell stack 201 is stopped, and the fuel cell system is shifted to the idle stop state.

  In this way, by setting the fuel cell system to the idle stop state, the operation of the auxiliary machines such as the hydrogen circulation pump 208 and the air compressor 212 is stopped, and in addition to the improvement of the fuel consumption, the improvement of the acoustic vibration performance and the low power consumption We are trying to make it.

  The procedure for releasing the idle stop state of the fuel cell system and restarting power generation is performed according to the flowchart shown in FIG.

  In FIG. 4, first, in S21, the hydrogen pressure regulating valve 204 is opened to start supplying hydrogen, and in S22, the air compressor 212 is driven to open the air pressure regulating valve 216 to start supplying air. Thereafter, power generation is started in S23, and the cooling water pump is driven in S24 to start supplying cooling water. Thus, current is taken out from the fuel cell stack 201 under the control of the system control unit 218, and the fuel cell system 102 returns from the idle stop state to the normal power generation state.

[Description of charging function after returning from idling stop]
Next, in the fuel cell system 102 having such an idle stop function, a method for charging the battery after the fuel cell system 102 returns from the idling stop state to the normal power generation state will be described.

  Under normal power generation conditions, the amount of power generated by the fuel cell is determined as the sum of the power equivalent to the driving force required by the drive motor, the auxiliary power required to operate the fuel cell itself, and the power charged in the battery. It is done. Also. The amount of charge to the battery is obtained, for example, according to the remaining amount of the battery, or the electric power to be charged is obtained so that the power generation efficiency of the fuel cell is high.

  FIG. 6 is a time chart for explaining a state in which the battery is charged after returning from the idling stop state in this embodiment, and FIG. 5 is a time chart in a comparative example to which the present invention is not applied.

  In the comparative example of FIG. 5, it is assumed that the stored amount of battery 107 (SOC) decreases due to discharging from the battery during idling stop, and the SOC decreases to, for example, 40%, which is the idling stop return condition, at time t1. The system control unit 218 that has determined the SOC condition starts the idling stop return control and activates the air compressor 212 in accordance with the flowchart shown in FIG. For example, at time t2, the fuel cell stack can generate power, and the extraction of the generated current starts.

  Then, charging of the battery starts at time t3. After that, the charging proceeds, for example, when the battery SOC reaches a charging target value, for example, 70%, at time t4, the charging stop operation is started, the hydrogen supply is throttled and the rotation speed of the air compressor is reduced, and at time t5 Reach idle speed.

  From time t2 to time t4, the system control unit 218 supplies hydrogen and air so that a power generation current for battery charging can be obtained in addition to normal auxiliary power consumption for idle. For this reason, the air compressor 212 is driven at, for example, 1900 [rpm] in order to supply the air amount including the charged amount, instead of the rotation speed 800 [rpm] of the air compressor 212 for normal idle.

  Thus, in the comparative example, at the time of idling stop recovery that requires charging, the rotational speed of the air compressor is, for example, 1900 [rpm], which is significantly higher than the idling stop state, and the acoustic vibration level is high, and the idling stop is performed. Drivers who are used to the quietness of the state will feel uncomfortable.

  In this embodiment, as shown in FIG. 6, until the time when it is determined to return from the idling stop at the time t1, it is the same as the comparative example, but after returning from the idle stop, the comparative example or the normal idling time For battery charging, the charging current to the battery is suppressed to be smaller than normal. As a result, the rotation speed of the air compressor can be suppressed to, for example, 1300 [rpm], which is lower than 1900 [rpm] in the charging state at the normal idling time, and the noise level is also reduced. It is possible to reduce the uncomfortable feeling and uncomfortable feeling given to the driver accustomed to the vehicle.

  The magnitude of the charging current after returning from the idling stop may be variable according to the length of the idling stop duration, for example. That is, as shown in FIG. 9A, the charging current is limited so that the idling stop duration is longer. The longer the idling stop duration is, the more familiar the user is with the silent state. Therefore, by controlling the charging current in this way, it is possible to further reduce discomfort and discomfort at the start of charging.

  Further, the magnitude of the charging current after returning from the idling stop may be variable according to the vehicle speed at the time of returning from the idling stop detected by the vehicle speed sensor, for example. That is, as shown in FIG. 10A, the charging current is limited so as to decrease as the vehicle speed at the time of idling stop return decreases. If the vehicle speed is low, the traveling sound of the vehicle is small, so the driver can easily feel the noise generated by the air compressor. Conversely, if the vehicle speed is high, the noise of the air compressor is easily hidden in the traveling sound. Controlling the charging current in this way can further reduce the sense of discomfort and discomfort at the start of charging.

  Further, the magnitude of the charging current after the idling stop return may be made variable according to the accelerator operation amount at the time of the idling stop return detected by the accelerator sensor 113. This tendency is the same as the change of the charging current with respect to the vehicle speed shown in FIG.

  The greater the amount of accelerator operation at the time of idling stop return, the more likely it is that the driver can tolerate a higher level of acoustic vibration, so by changing the method of charging according to the amount of accelerator operation, the minimum necessary acoustic vibration Suppressing the level.

  Furthermore, the magnitude of the charging current after returning from idling stop may be made variable according to the vehicle interior noise level at returning from idling stop calculated based on the vehicle interior acoustic signal input from the microphone 116. This tendency is the same as the change of the charging current with respect to the vehicle speed shown in FIG.

  It seems that the higher the noise in the passenger compartment at the time of idling stop return, the higher the acoustic vibration level can be tolerated by the driver, so by changing the charging method according to the noise level in the passenger compartment, the minimum required It can be suppressed to suppress the acoustic vibration level.

  Next, a second embodiment of the fuel cell system according to the present invention will be described. The present embodiment is characterized in that when the fuel cell returns to the power generation state after the idling stop is canceled, the charging of the battery is suppressed by delaying the charging start of the battery by the charging start delay time.

  An example of a fuel cell vehicle on which the fuel cell system of Example 2 is mounted and a configuration example of a fuel cell system to which Example 2 is applied are the same as those of Example 1 shown in FIGS. 1 and 2. Further, the process for shifting the fuel cell system to the idling stop and the process for returning the fuel cell system from the idling stop are the same as those in the first embodiment shown in FIGS.

  FIG. 7 is a time chart for explaining a state in which the battery is charged after returning from the idling stop state in the present embodiment. The charging of the battery is suppressed by delaying the charging start of the battery from the time (t1) when it is determined to return from the idling stop state to the time ta when the charging start delay time elapses. During this charging start delay time, the fuel cell stack generates power for the normal idle amount corresponding to the auxiliary machine power consumption, so the rotational speed of the air compressor is 800 [rpm] during normal idle time. Then, after the user gets used to the air compressor noise generated during normal idling (time ta), battery charging is started, and the rotation speed of the air compressor is increased to the rotation speed during normal charging, for example, 1900 [rpm]. Therefore, compared to increasing the rotational speed of the air compressor to 1900 [rpm] immediately after returning from idling stop, there is an effect that the uncomfortable feeling and discomfort given to the driver can be reduced.

  The length of the charging start delay time may be variable according to the length of the idling stop duration, for example. That is, as shown in FIG. 9B, the charging start delay time is controlled to be longer as the idling stop duration is longer. As the idling stop duration is longer, the user is used to a quieter state. Thus, by controlling the length of the charging start delay time in this way, it is possible to further reduce discomfort and discomfort at the start of charging.

  Further, the length of the charging start delay time may be variable depending on the vehicle speed at the time of idling stop return detected by the vehicle speed sensor, for example. That is, as shown in FIG. 10B, the charging start delay time is controlled to be longer as the vehicle speed at the time of idling stop return is lower. If the vehicle speed is low, the traveling sound of the vehicle is small, so the driver can easily feel the noise generated by the air compressor. Conversely, if the vehicle speed is high, the noise of the air compressor is easily hidden in the traveling sound. Controlling the length of the charging start delay time in this way can further reduce discomfort and discomfort at the start of charging.

  Further, the magnitude of the charging current after the idling stop return may be made variable according to the accelerator operation amount at the time of the idling stop return detected by the accelerator sensor 113. This tendency is the same as the change of the charging current with respect to the vehicle speed shown in FIG.

  The greater the amount of accelerator operation at the time of idling stop return, the more likely it is that the driver can tolerate a higher level of acoustic vibration, so by changing the method of charging according to the amount of accelerator operation, the minimum necessary acoustic vibration Suppressing the level.

  Furthermore, the magnitude of the charging current after returning from idling stop may be made variable according to the vehicle interior noise level at returning from idling stop calculated based on the vehicle interior acoustic signal input from the microphone 116. This tendency is the same as the change of the charging current with respect to the vehicle speed shown in FIG.

  It seems that the higher the noise in the passenger compartment at the time of idling stop return, the higher the acoustic vibration level can be tolerated by the driver, so by changing the charging method according to the noise level in the passenger compartment, the minimum required It can be suppressed to suppress the acoustic vibration level.

  Next, a third embodiment of the fuel cell system according to the present invention will be described. The present embodiment is characterized in that, when the fuel cell returns to the power generation state after the idling stop is released, charging to the battery is suppressed by limiting the rate of increase of the charging current to the battery.

  An example of a fuel cell vehicle on which the fuel cell system of Example 3 is mounted and a configuration example of a fuel cell system to which Example 3 is applied are the same as those of Example 1 shown in FIGS. Further, the process for shifting the fuel cell system to the idling stop and the process for returning the fuel cell system from the idling stop are the same as those in the first embodiment shown in FIGS.

  FIG. 8 is a time chart for explaining a state in which the battery is charged after returning from the idling stop state in the present embodiment. After determining to return from the idling stop state at time t1, it is possible to extract current from the fuel cell stack at time t2, and the auxiliary device consumption current is switched from the battery to the fuel cell. At time t3, the generated current exceeds the auxiliary machine consumption current and charging starts. At this time, the rate of increase in charging current per hour is limited, and the rate of increase in the rotational speed of the air compressor 212 is also limited accordingly.

  By limiting the rate of increase of the charging current per hour, the rotational speed of the air compressor is changed from 800 [rpm] at normal idling time at time t2 (or t3), for example, at normal charging time at time tb. The rotational speed of the air compressor is gradually increased to 1900 [rpm].

  In this way, the rate of increase of the charging current per hour to the battery is limited, so the noise generated by the air compressor gradually increases, so that the rotation speed of the air compressor is set to the normal rotation speed immediately after the idling stop is returned. Compared to the increase in speed, there is an effect that the uncomfortable feeling and discomfort given to the driver can be reduced.

  The magnitude of the increase rate of the charging current per time may be variable according to the length of the idling stop duration, for example. That is, as shown in FIG. 9C, control is performed such that the rate of increase in charging current per hour increases as the idling stop duration time increases. As the idling stop duration is longer, the user is used to a quieter state. Thus, by controlling the rate of increase in charging current per hour in this way, it is possible to further reduce discomfort and discomfort at the start of charging.

  Further, the rate of increase of the charging current per hour may be variable according to the vehicle speed at the time of idling stop return detected by the vehicle speed sensor, for example. That is, as shown in FIG. 10C, control is performed such that the rate of increase in charging current per hour increases as the vehicle speed at the time of idling stop return decreases. If the vehicle speed is low, the traveling sound of the vehicle is small, so it is easy to feel the noise generated by the air compressor. Conversely, if the vehicle speed is high, the noise of the air compressor is easily hidden in the traveling sound. Controlling the rate of increase in charging current per hour in this way can further reduce discomfort and discomfort at the start of charging.

  Further, the magnitude of the charging current after the idling stop return may be made variable according to the accelerator operation amount at the time of the idling stop return detected by the accelerator sensor 113. This tendency is the same as the change of the charging current with respect to the vehicle speed shown in FIG.

  The greater the amount of accelerator operation at the time of idling stop return, the more likely it is that the driver can tolerate a higher level of acoustic vibration, so by changing the method of charging according to the amount of accelerator operation, the minimum necessary acoustic vibration Suppressing the level.

  Furthermore, the magnitude of the charging current after returning from idling stop may be made variable according to the vehicle interior noise level at returning from idling stop calculated based on the vehicle interior acoustic signal input from the microphone 116. This tendency is the same as the change of the charging current with respect to the vehicle speed shown in FIG.

  It seems that the higher the noise in the passenger compartment at the time of idling stop return, the higher the acoustic vibration level can be tolerated by the driver, so by changing the charging method according to the noise level in the passenger compartment, the minimum required It can be suppressed to suppress the acoustic vibration level.

  Next, a fourth embodiment of the fuel cell system according to the present invention will be described. The present embodiment is an embodiment in which the first, second, and third embodiments are implemented together, and has the effect of combining the effects of the first to third embodiments. The example of the fuel cell vehicle on which the fuel cell system of Example 4 is mounted and the configuration example of the fuel cell system to which Example 4 is applied are the same as those of Example 1 shown in FIGS. Further, the process for shifting the fuel cell system to the idling stop and the process for returning the fuel cell system from the idling stop are the same as those in the first embodiment shown in FIGS.

  FIGS. 11 and 12 are flowcharts for explaining the charge control after the idling stop is released in this embodiment, and FIG. 13 explains the state in which the battery is charged after returning from the idling stop state in the present embodiment. It is a time chart. In this embodiment, reference is made as a control table TWi = fi, DIi = gi, Ii = hi (i = 1, 2, 3) storing control parameters as shown in FIGS. 9 and 10 in advance.

  In step (hereinafter abbreviated as “S”) 31 in FIG. 11, it is determined whether an idle stop cancellation condition is satisfied. This release condition is, for example, a condition in which the accelerator operation amount is equal to or greater than a predetermined value, or the battery SOC is equal to or less than a predetermined value (for example, 40%). If the determination in S31 is No, the process returns without doing anything. If the determination in S31 is Yes, the process proceeds to S32, where the value of Flag, which is a work flag, is initialized to 0, and the work parameter area is further initialized.

  Next, in S33, it is determined whether or not the idle stop duration T from when the idle stop is started until when the idle stop cancellation condition is satisfied is equal to or greater than a predetermined value T1. This predetermined value T1 collects data relating to the degree of discomfort of the plurality of drivers with respect to the idle stop duration, and if the idle stop duration is equal to or shorter than this time, charging suppression after releasing the idle stop is not performed. Is set as the predetermined value T1.

  If judgment of S33 is Yes, it will progress to S34. If judgment of S33 is No, it will progress to S35. In S34, Flag is set to 1, TW1 is obtained by referring to the control table f1 (T) indicating the relationship of the first charge start delay time TW1 to the idle stop duration T, and the first charge for the idle stop duration T is obtained. DI1 is obtained with reference to the control table g1 (T) indicating the relationship of the current increase rate DI1, and I1 with reference to the control table h1 (T) indicating the relationship of the first charging current limit value I1 to the idle stop duration T. And go to S35.

  Next, in S35, the vehicle speed V detected by the vehicle speed sensor is read, and in S36, it is determined whether or not the vehicle speed V is smaller than a predetermined value V1. This predetermined value V1 collects data related to the degree of discomfort of a plurality of drivers with respect to the vehicle speed after returning from idle stop. If the vehicle speed is higher than this vehicle speed, charging is not particularly performed after idle stop is released. A vehicle speed that does not cause a sense of incongruity is set as the predetermined value V1.

  If judgment of S36 is Yes, it will progress to S37. If judgment of S36 is No, it will progress to S38. In S37, Flag is set to 1, TW2 is obtained with reference to the control table f2 (V) indicating the relationship of the second charging start delay time TW2 to the vehicle speed V at the time of idling stop return, and the vehicle speed V at the time of idling stop return. Referring to a control table g2 (V) showing the relationship of the second charging current increase rate DI2 with respect to, DI2 is obtained, and a control table h2 (V ) To obtain I2 and proceed to S38.

  Next, in S38, the accelerator operation amount A detected by the accelerator sensor is read. In S39, it is determined whether or not the accelerator operation amount A is smaller than a predetermined value A1. This predetermined value A1 collects data related to the degree to which a plurality of drivers feel uncomfortable with respect to the accelerator operation amount after returning from the idle stop. If the operation amount is greater than this accelerator operation amount, charging suppression particularly after releasing the idle stop is performed. The accelerator operation amount that does not cause a sense of incongruity even if the operation is not performed is set as the predetermined value A1.

  If judgment of S39 is Yes, it will progress to S40. If judgment of S39 is No, it will progress to S41. In S40, Flag is set to 1, TW3 is obtained with reference to the control table f3 (A) indicating the relationship of the third charging start delay time TW3 to the accelerator operation amount A at the time of idling stop return, and at the time of idling stop return. Referring to the control table g3 (A) showing the relationship of the third charging current increase rate DI3 to the accelerator operation amount A, DI3 is obtained, and the relationship of the third charging current limit value I3 to the accelerator operation amount A at the time of the idle stop return is obtained. The control table h3 (A) shown is referred to to obtain I3, and the process proceeds to S41.

  Next, in S41, the vehicle interior acoustic signal detected by the microphone is read, and the vehicle interior noise level N is calculated based on this acoustic signal. Next, in S42, it is determined whether or not the vehicle interior noise level N is smaller than a predetermined value N1. This predetermined value N1 collects data related to the degree of discomfort of a plurality of drivers with respect to the vehicle interior noise level after returning from the idle stop. A vehicle interior noise level that does not cause a sense of incongruity even if not performed is set as a predetermined value N1.

  If judgment of S42 is Yes, it will progress to S43. If judgment of S42 is No, it will progress to S44. In S44, Flag is set to 1, TW4 is obtained with reference to the control table f4 (N) indicating the relationship of the fourth charging start delay time TW4 to the vehicle interior noise level N at the time of idling stop return, and at the time of idling stop return. DI4 is obtained with reference to a control table g4 (N) showing the relationship of the fourth charging current increase rate DI4 with respect to the vehicle interior noise level N, and the fourth charging current limit value I4 with respect to the vehicle interior noise level N at the time of idling stop return. I4 is obtained by referring to the control table h4 (N) indicating the relationship, and the process proceeds to S44.

  In S44, a charging start delay time TW, a charging current increase rate DI, and a charging current limit value I that are actually used for suppressing charging are obtained. The charging start delay time TW is set to TW by obtaining the maximum value from TW1, TW2, TW3, and TW4. The charging current increase rate DI is determined as DI by obtaining the minimum value from DI1, DI2, DI3, and DI4. The charging current limit value I 1 is obtained by obtaining the minimum value from I 1, I 2, I 3, and I 4.

  Next, in S45, it is determined whether or not the value of the flag Flag is 1. If Yes, the process proceeds to S51 in FIG. 12 in order to perform charge suppression control. If it is No, it will not perform charge suppression but will move to normal charge control.

  In the battery charge suppression control in S51 and subsequent steps in FIG. 12, charge start delay control, charge current increase rate suppression control, and charge current limit control are performed. FIG. 13 is a time chart showing the state of the charging power suppression control.

  In FIG. 12, first, in S51, the process waits until the charging start delay time TW elapses. This TW corresponds to the period from t1 to ta in FIG. During this time, the air compressor is operated at a rotational speed of 800 [rpm] during idling in order to supply an air flow rate necessary for generating electric power corresponding to a normal idling amount, that is, an amount corresponding to the power consumption of the auxiliary equipment of the fuel cell. .

  After TW elapses in S51, the process proceeds to S52, and charging is started with the charging current Ic = DI. Next, the battery SOC is detected in S53, and it is determined in S54 whether or not the SOC is equal to or greater than a predetermined value SOC1 (for example, 70%) at which charging ends. If it is determined in S54 that the SOC is SOC1 or more, the process proceeds to a charge end process. In the charge termination process, for example, the hydrogen supply is reduced to the hydrogen pressure during normal idling, and the rotation speed of the air compressor is decreased to a rotation speed of 800 [rpm] corresponding to the air supply amount during normal idling.

  If the SOC is less than SOC1 in the determination of S54, after charging for 1 second with the current charging current Ic, the process proceeds to S56. In S56, the charging current Ic is increased by DI, the rotational speed of the air compressor is increased by the increase in charging current, and the process returns to S53. In this way, the battery can be charged by limiting the rate of increase in charging current per hour to DI. The period during which the rate of increase of the charging current per hour is limited is the period from time ta to time tb in FIG.

  When the charging current Ic is increased by DI in S56, it is determined whether or not the charging current Ic is equal to or higher than the charging current limit value I. If the charging current Ic is equal to or higher than the charging current limit value I, the charging current is set to I If it restrict | limits to, the restriction | limiting of a charging current can also be performed simultaneously. This charging current limiting period is a period between time tb and time t4 in FIG.

It is a block diagram explaining the structure of the fuel cell vehicle to which the fuel cell system which concerns on this invention is applied. It is a block diagram explaining the structure of the fuel cell system which concerns on this invention. It is a flowchart explaining an idling stop transfer process. It is a flowchart explaining an idling stop return process. It is a time chart explaining the charge control after the idling stop cancellation | release in the comparative example which does not apply this invention. It is a time chart explaining charge control after idling stop cancellation in Example 1 of the fuel cell system concerning the present invention. It is a time chart explaining the charge control after idling stop cancellation | release in Example 2 of the fuel cell system which concerns on this invention. It is a time chart explaining the charge control after idling stop cancellation | release in Example 3 of the fuel cell system which concerns on this invention. (A) Charging current value with respect to idling stop duration in Example 1, (b) Charging start delay time with respect to idling stop duration in Example 2, (c) Charging current increase rate with respect to idling stop duration in Example 3; It is a figure which shows the example of. (A) Charging current value with respect to vehicle speed at idling stop return in Example 1, (b) Charge start delay time with respect to vehicle speed at idling stop return in Example 2, (c) Charging current with respect to vehicle speed at idling stop return in Example 3 It is a figure which shows the example of an increase rate. It is the first half part of the flowchart explaining the charge control after idling stop cancellation | release in Example 4 of the fuel cell system which concerns on this invention. It is a second half part of the flowchart explaining the charge control after idling stop cancellation | release in Example 4 of the fuel cell system which concerns on this invention. It is a time chart explaining charge control after idling stop cancellation in Example 4 of the fuel cell system concerning the present invention.

Explanation of symbols

101: fuel cell vehicle 102: fuel cell system 103: inverter 104: drive motor 105: drive wheel 106: vehicle speed sensor 107: battery 108: relay 109: controller 111: shift position sensor 112: brake sensor 113: accelerator sensor 114: battery Voltage sensor 115: Battery current sensor 116: Microphone

Claims (8)

A fuel cell that generates electricity by an electrochemical reaction between a fuel gas and an oxidant gas;
Power storage means for supplying power when the fuel cell power is insufficient while the fuel cell is charged with the power generated by the fuel cell;
At least the supply of the oxidant gas to the fuel cell is temporarily stopped, and the power generation of the fuel cell is temporarily stopped to shift to the idling stop state, while the idling stop state is canceled and at least the oxidant gas is supplied. Idling stop control means for restarting and restarting power generation,
Charging control means for charging the power storage means by increasing the power generation amount of the fuel cell according to the power storage amount of the power storage means;
In a fuel cell system comprising:
The fuel cell system, wherein the charge control unit suppresses charging of the power storage unit from a normal operation after the idling stop state is canceled and the power generation state is shifted.   2. The fuel cell system according to claim 1, wherein the charging control unit does not charge the power storage unit during a charging start delay time after returning from idling stop. 3.   2. The fuel cell system according to claim 1, wherein the charging control unit sets an increasing rate of a charging current to the power storage unit smaller than that during normal operation after returning from idling stop.   2. The fuel cell system according to claim 1, wherein the charging control unit sets a charging current to the power storage unit to be smaller than that during normal operation for a predetermined time after returning from idling stop.   The charging control means sets the charging start delay time, the charging current increase rate, and the charging current based on an idling stop time that is a time during which the idling stop is continued. The fuel cell system according to claim 4. Equipped with a vehicle speed sensor for detecting the speed of a vehicle equipped with a fuel cell system;
The charge control means sets any one of the charge start delay time, the charge current increase rate, and the charge current based on a vehicle speed at the time of idling stop return. The fuel cell system according to any one of claims. An accelerator sensor for detecting an accelerator operation amount of a vehicle equipped with a fuel cell system;
The charge control means sets any one of the charge start delay time, the charge current increase rate, and the charge current based on an accelerator operation amount at the time of idling stop return. 5. The fuel cell system according to any one of 4 above. A noise level detecting means for detecting or estimating a noise level in a passenger compartment of a vehicle equipped with a fuel cell system;
The charge control means sets any one of the charge start delay time, the charge current increase rate, and the charge current based on a noise level in the vehicle interior at the time of idling stop return. The fuel cell system according to claim 4.

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