JP2006134771A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system capable of appropriately starting the control of a drain valve in starting of the next operation even when water in a drain system is freezed during the stop of a fuel cell. <P>SOLUTION: The fuel cell system is equipped with the fuel cell, a catch tank storing water produced by the power generation of the fuel cell, the drain valve 26 exhausting the water in the catch tank, and an ECU 3 controlling the drain valve 26. The ECU 3 is equipped with a freezing judgement means 31 judging whether water in the drain system is freezed or not and a thawing judgement means 33 judging whether ice in the drain system is thawed or not based on the total heating value of the fuel cell when the freezing judgement means 31 judged that water is freezed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel cell system provided with a steam separator.

  In general, a fuel cell is configured such that a cathode electrode is defined on one side and an anode electrode is defined on the other side with a proton conductive polymer electrolyte membrane interposed therebetween, and oxygen in the air supplied to the cathode electrode. And electricity generated by an electrochemical reaction with hydrogen supplied to the anode electrode. A fuel cell system including such a fuel cell includes a circulation channel for returning unreacted hydrogen gas (hereinafter also referred to as “hydrogen offgas”) discharged from the fuel cell to the fuel cell again. Systems equipped are known.

  By the way, in the fuel cell system as described above, water is generated mainly by the electrochemical reaction between hydrogen and oxygen on the cathode electrode side, and this water enters the anode electrode through the polymer electrolyte membrane. ing. Therefore, moisture is contained in the hydrogen off-gas discharged from the fuel cell, and such a problem occurs that the hydrogen off-gas containing such moisture is supplied to the fuel cell again, thereby reducing the power generation performance of the fuel cell. .

  As a technique for solving such a problem, a structure in which an air-water separator for separating moisture in hydrogen off-gas is conventionally provided in a circulation channel for returning hydrogen to the fuel cell again (patent) Reference 1). Specifically, this steam separator is composed of a heat exchanger for condensing water in the hydrogen off gas as a liquid, a tank for storing water condensed by the heat exchanger, and water in the tank. And a drain valve for switching the conduction state of the drain line. In this technique, when a predetermined amount or more of water has accumulated in the tank, the drain valve is appropriately opened and closed to discharge the water in the tank.

JP-A-8-321316

  However, in the above-described technology, the operation of the fuel cell is completed with water remaining in the drain system (in the tank, in the drain line, in the drain valve), and after a long time has passed, the winter or cold districts Then, there was a possibility that the water might freeze. And when the water in the drain system freezes in this way, for example, in a system that controls the drain valve with the start of the fuel cell, a current is passed unnecessarily to the drain valve that is frozen and cannot be opened. As a result, energy may be wasted.

  Also, in a system that controls the drain valve after a certain time has elapsed since the start of the fuel cell, a phenomenon that the drain valve control is not started even though it has already been thawed occurs, which causes power generation in the anode system. Condensed water would stagnate, and there was a risk that the power generation capacity would be significantly reduced, such as reducing the power generation voltage. Furthermore, while the water in the drain system is frozen, a system that discharges the water in the circulation flow path together with the hydrogen off-gas using a valve other than the drain valve can prevent a decrease in power generation capacity. If water continues to be discharged by other valves even though the water has already been thawed, the hydrogen off-gas discharged with this water will be wasted. In this case, it was desired to immediately shift to the control of the drain valve after determining that the thawing was performed.

  Therefore, the present invention provides a fuel cell system capable of appropriately starting drain valve control at the next startup even when water in the drain system is frozen while the fuel cell is stopped. With the goal.

  The invention according to claim 1 of the present invention that solves the above problems includes a fuel cell that generates power by reacting a reaction gas, a water reservoir that stores water generated by the power generation of the fuel cell, and the water reservoir. A drain valve for discharging the water, and a freezing judgment means for judging whether or not the water in the water reservoir and the drain valve is frozen when the fuel cell is started. The ice in the water reservoir and the drain valve is thawed based on a parameter that changes in relation to the thawing of ice in the water reservoir or the drain valve when the freezing determination means determines that the ice is frozen. And a decompression judging means for judging whether or not it has been done.

  Here, “a parameter that changes in relation to the thawing of ice in the water reservoir or the drain valve” is, for example, the total amount of heat applied to the water reservoir that gradually increases as the ice in the water reservoir progresses. It also refers to parameters such as the temperature of the water reservoir that rises after the ice in the water reservoir has completely thawed.

  According to the first aspect of the present invention, when the fuel cell is started, first, it is determined whether or not the water in the water reservoir and the drain valve is frozen by the freezing determination means. When it is determined by the freezing determination means that the water is not frozen, for example, the control is transferred to the normal drain valve control, and when it is determined that the water is frozen, the signal is output to the thawing determination means. . In the thawing determination means, when the signal is received from the freezing determination means, whether or not the ice in the water reservoir and the drain valve has been thawed based on, for example, the temperature of the water reservoir (a parameter that changes in relation to the thawing of ice). Determine whether.

  A second aspect of the present invention is the fuel cell system according to the first aspect, further comprising a calorific value integrating means for integrating the calorific value from the start of the fuel cell to the present as the parameter, wherein the thawing determination The means is characterized in that when the calorific value accumulated by the calorific value accumulating means exceeds a predetermined value, it is determined that the ice in the water reservoir and the drain valve has been thawed.

  According to the second aspect of the present invention, when the fuel cell is started, as described above, it is determined whether or not the water in the water reservoir and the drain valve is frozen by the freezing determination means, and the calorific value integration is performed. By the means, integration of the amount of heat generated from the fuel cell is started. When it is determined that the water is frozen by the freezing determination means, the thawing determination means determines whether or not the heat generation amount accumulated by the heat generation amount integration means exceeds a predetermined value. It is determined whether the ice in the section and the drain valve has been thawed. The thawing determination means determines that the ice in the water reservoir and the drain valve has been thawed when it is determined that the calorific value exceeds a predetermined value.

  The invention according to claim 3 is the fuel cell system according to claim 1, further comprising temperature detecting means for detecting the temperature in the water reservoir or the drain valve as the parameter, When the temperature detected by the temperature detecting means exceeds a predetermined value, it is determined that the ice in the water reservoir and the drain valve has been thawed.

  According to the third aspect of the present invention, when the fuel cell is started, as described above, it is determined whether or not the water in the water reservoir and the drain valve is frozen by the freezing determining means, and the temperature detecting means. For example, the temperature in the drain valve is detected. Then, when it is determined that the water is frozen by the freezing determination means, the thawing determination means determines whether the temperature detected by the temperature detection means exceeds a predetermined value, thereby determining whether the water reservoir and the drain valve are within the predetermined range. Determine whether the ice has been thawed. The thawing determination means determines that the ice in the water reservoir and the drain valve has been thawed when it is determined that the temperature exceeds a predetermined value.

  Invention of Claim 4 is a fuel cell system of Claim 1, Comprising: While the said water reservoir is provided in the reaction gas flow path used as the passage of the said reaction gas, at the time of starting of the said fuel cell, the said Drain valve opening means for opening the drain valve; and reaction gas detection means for detecting the amount of the reaction gas discharged from the drain valve opened by the drain valve opening means as the parameter. The thawing determination means determines that the ice in the water reservoir and the drain valve has been thawed when the amount of the reaction gas detected by the reaction gas detection means exceeds a predetermined value. And

  According to the fourth aspect of the present invention, for example, in a fuel cell system having a structure in which water does not accumulate in the drain valve, when the fuel cell is started, as described above, the freezing determination means causes the inside of the water reservoir and drain to be It is determined whether or not the water in the valve is frozen, the drain valve is opened by the drain valve opening means, and detection of the reaction gas is started by the reaction gas detection means. When it is determined that the water is frozen by the freezing determination means, the thawing determination means determines whether or not the amount of the reaction gas detected by the reaction gas detection means exceeds a predetermined value, that is, the ice in the drain system By determining whether or not a predetermined amount of the reaction gas has been discharged from the drain valve, it is determined whether or not the ice in the water reservoir and the drain valve has been thawed. The thawing determination means determines that the ice in the water reservoir and the drain valve has been thawed when it is determined that the amount of the reaction gas exceeds a predetermined value.

  According to the first aspect of the present invention, when the water in the drain system is frozen, the thawing determination means determines whether or not the ice has thawed, so that water can be discharged from the drain valve. Can be accurately grasped. Therefore, even when the water in the drain system is frozen while the fuel cell is stopped, the drain valve can be appropriately controlled at the next startup.

  According to the second aspect of the present invention, the thawing determination is performed based on the integrated value of the calorific value of the fuel cell obtained from parameters detected in a normal fuel cell system such as a current value and a voltage value. Therefore, it is not necessary to provide a dedicated sensor, and the number of parts can be reduced, and the cost and weight can be reduced.

  According to the third aspect of the present invention, since the temperature in the vicinity of the drain valve is directly detected by the temperature detecting means, it is possible to make a reliable thawing determination.

  According to the invention described in claim 4, since it is determined that the ice closing the drain system is thawed by the reaction gas being discharged from the drain valve, it is possible to make a reliable thaw determination. It becomes.

[First Embodiment]
Next, a first embodiment of the present invention will be described in detail with reference to the drawings as appropriate. In the drawings to be referred to, FIG. 1 is a configuration diagram showing a fuel cell system according to the first embodiment, and FIG. 2 is a block diagram showing a configuration of the ECU of FIG.

  As shown in FIG. 1, the fuel cell system S includes a fuel cell FC that supplies current to the traveling motor M, an air supply system 1 that supplies air to the fuel cell FC, and hydrogen that supplies hydrogen to the fuel cell FC. Supply system 2, ECU (control device) 3 for controlling various devices, voltmeter 41 for detecting the voltage generated in fuel cell FC, and current for detecting current flowing from fuel cell FC A total 42 and an outside air temperature sensor 43 for detecting the outside air temperature are provided.

  The fuel cell FC has a structure in which a cathode electrode is partitioned on one side and an anode electrode is partitioned on the other side with a proton conductive polymer electrolyte membrane interposed therebetween, and oxygen in the air supplied to the cathode electrode. Power is generated by an electrochemical reaction with hydrogen supplied to the anode electrode. Therefore, in the fuel cell FC, water is mainly generated on the cathode electrode side with power generation, and this water enters the hydrogen supply system 2 through the polymer electrolyte membrane.

  The air supply system 1 includes a compressor C that compresses and supplies air, an air flow path 11 that guides the air from the compressor C to the fuel cell FC, and guides the air discharged from the fuel cell FC to the outside. A back pressure valve 12 is provided mainly at the outlet of the air flow path 11 and controls the pressure (back pressure) on the cathode electrode side.

  The hydrogen supply system 2 mainly includes a hydrogen tank HT, a hydrogen supply channel 21, a shutoff valve 22, an ejector 23, a circulation channel 24, a catch tank (water reservoir) 25, and a drain valve 26. The hydrogen tank HT is filled with hydrogen as a fuel gas (reactive gas). This hydrogen is released by opening a shutoff valve 22 and a solenoid valve (not shown) provided in the hydrogen tank HT. The fuel cell FC is discharged through the hydrogen supply channel 21. The ejector 23 mixes the hydrogen from the hydrogen tank HT and the hydrogen returned from the fuel cell FC, and supplies the fuel again to the fuel cell FC to circulate the hydrogen. The circulation flow path 24 is a flow path for returning hydrogen discharged from the fuel cell FC to the fuel cell FC again via the ejector 23, and a catch tank 25 is attached at an appropriate position thereof.

  The catch tank 25 is a tank having a function of gas-liquid separation for separating hydrogen gas containing moisture discharged from the fuel cell FC into hydrogen gas and water, and has a structure in which the separated water is accumulated at the bottom. It has become. A drain line 25a is connected to the bottom of the catch tank 25 to guide water inside the catch tank 25, and a drain valve 26 is provided on the drain line 25a. Note that the catch tank 25 is disposed at a lower position in consideration of water discharge performance in the fuel cell system S, that is, at a position where residual water in the fuel cell FC and the circulation flow path 24 is likely to accumulate.

  The drain valve 26 is appropriately controlled to be opened and closed by the ECU 3 in order to discharge the water in the catch tank 25. In the following description, for convenience, the drain valve 26, the catch tank 25 and the drain line 25a are collectively referred to as a drain system D.

  The ECU 3 controls each device of the fuel cell system S, mainly the compressor C, the air purge valve 12, the shutoff valve 22, and the drain valve 26. In particular, the ECU 3 performs control to determine whether or not the drain system D is frozen when the fuel cell FC is started up, and to determine whether or not the ice has thawed when it is frozen. The details will be described below.

  As shown in FIG. 2, the ECU 3 includes a freezing determination unit 31, a calorific value integration unit 32, a thawing determination unit 33, and a drain valve control unit 34.

  When the fuel cell FC is started up, the freezing determination means 31 is based on a signal (temperature) output from the outside air temperature sensor 43, and the outside air temperature is once between the stop of the fuel cell FC and the next start-up. However, it has a function of determining whether or not the water in the drain system D is frozen by determining whether or not the temperature is below freezing point. Specifically, the freezing determination means 31 always captures and stores the outside air temperature detected by the outside air temperature sensor 43 while the fuel cell FC is stopped, and the previous stop when the fuel cell FC is started next time. From the accumulated data of the temperature stored until the start of this time, it is determined whether or not the outside air temperature has become below freezing point, and when the fuel cell FC is stopped again, the accumulated data is deleted and a new Memorize the accumulated data. The freezing determination means 31 is configured to output a signal indicating the result to the thawing determination means 33 when it is determined whether or not the water in the drain system D is frozen.

  The calorific value integrating means 32 starts the fuel cell FC based on the voltage value sent from the voltmeter 41, the current value sent from the ammeter 42, the elapsed time since the fuel cell FC was started, and the like. It has a function to integrate the calorific value from the present to the present. The calorific value integrating means 32 is configured to output the accumulated total calorific value to the thawing determining means 33. In the first embodiment, the total calorific value corresponds to “a parameter that changes in relation to the thawing of ice in the water reservoir or the drain valve” in the claims.

  The thawing judging means 33 refers to the signal from the calorific value integrating means 32 when the signal sent from the freezing judging means 31 is “a signal indicating that the water in the drain system D is frozen”. , Has a function of determining whether or not the ice in the drain system D has been thawed. Specifically, the thawing determination means 33 is sent from the calorific value integration means 32 when a “signal indicating that the water in the drain system D is frozen” is sent from the freezing judgment means 31. A function for determining whether or not the total calorific value of the fuel cell FC exceeds a predetermined value and determining that the ice in the drain system D has been thawed when it is determined that the total calorific value exceeds the predetermined value. Have.

  The thawing determination means 33 also thaws the ice in the drain system D even when the signal sent from the freezing determination means 31 is a “signal indicating that the water in the drain system D is not frozen”. It has the function to judge that it is done. The thawing determination means 33 does not send a signal to the drain valve control means 34 while determining that the ice in the drain system D has not been thawed, but only when it is determined that the ice has been thawed. Is output to the drain valve control means 34.

  The drain valve control means 34 has a function of opening the drain valve 26 under normal control when a “signal indicating that the thawing is performed” is sent from the thawing determination means 33. Here, the normal control refers to, for example, control for opening the drain valve 26 a predetermined number of times during a predetermined time when the water level accumulated in the catch tank 25 becomes a predetermined value or more.

  Next, the operation of the ECU 3 will be described with reference to FIGS. 1 and 3. In the drawings to be referred to, FIG. 3 is a flowchart (a) showing the operation of the ECU until the drain valve is normally controlled, a flowchart (b) showing the operation of the ECU based on the subroutine of FIG. 3 (a), and FIG. It is map (c) referred in the step which accumulates the calorific value of (b).

  As shown in FIGS. 1 and 3A, when the ignition switch (IGSW) is turned on by the driver, the ECU 3 first opens the shutoff valve 22, the back pressure valve 12, and the compressor C. By driving, air and hydrogen gas, which are reaction gases, are supplied to the fuel cell FC (step S1). Then, after starting the power generation of the fuel cell FC in step S1, the process proceeds to the thawing determination process (step S2).

  In the thawing determination step, as shown in FIG. 3 (b), first, whether or not the outside air temperature has fallen below the freezing point between the previous stop of the fuel cell FC and the current start-up, that is, the previous time of the fuel cell FC. It is determined whether or not the outside air temperature has always exceeded 0 ° C. from the stop to the current start (step S11). In step S11, when it is determined that the outside air temperature has fallen below freezing point (No), the current power W is calculated from the current voltage V and current I (step S12).

  The calculation of the work rate W in step S12 is performed using the map showing the IV characteristic shown in FIG. Specifically, the work rate W is calculated by multiplying the difference between the voltage V0 when the current I is 0 A (ampere) and the current voltage V by the current current I.

Then, after step S12, the process proceeds to step S13 to determine whether or not a flag to be described later is set (whether or not “Flag = 1”). If it is determined in step S13 that the flag is not set (No), the process proceeds to step S14, the flag is set, and the timer is started to measure the elapsed time from the start of the fuel cell FC. It will be. If it is determined in step S13 that the flag is set (Yes), the timer started in step S14 is referred to and the current work rate Wn _-1 is calculated (step S12). elapsed time is calculated to the work rate W _n calculated in (step S15).

After step S15, the process proceeds to step S16, and based on the work rate calculated in step S12, the elapsed time calculated in step S15, and the work amount which is a fixed value, the heat generation amount Q of the current fuel cell FC. _n is calculated, and this calorific value Q _n is added to the calorific values Q _{1 to} Q _n−1 previously calculated. Here, the calorific value Q _n is calculated by the following equation.
Q _n = W _n × T _n ÷ K
(Q _n: calorific value, W _n: This work rate, T _n: elapsed time of the current, K: the amount of work [fixed value; 4.2 J])
Also, after step S14, the process proceeds to step S16, since this time is not performed to calculate the elapsed time in step S15, the calorific value Q ₁ is a 0 J (Joule).

  Then, after step S16, it is determined whether or not the total calorific value Q accumulated in step S16 exceeds a predetermined value (step S17), and if it is determined that it does not exceed the predetermined value (No). The processes in steps S11 to S17 are repeated again. Here, the predetermined value referred to in step S17 is an amount of heat that can be thawed by the ice of the drain system D, and an experiment or simulation taking into account that the total calorific value from the fuel cell FC is absorbed by each device. For example, it is calculated in advance. The predetermined value does not need to be fixed to a value calculated in advance as in the present embodiment. For example, a map that takes into account the water level of the water in the catch tank 25, the outside temperature, and the like is created, and this map You may make it change suitably based on.

  If it is determined in step S17 that the predetermined value has been exceeded (Yes), or if it is determined in step S11 that the outside temperature has never become below freezing while the fuel cell FC is stopped (Yes), Proceeding to S18, it is determined that the ice in the drain system D has been thawed (or has already been thawed). Thereafter, if the flag is set in step S14, the flag is returned to the original in step S19 ("Flag = 0" is set), and the operation of this subroutine (decompression determination step) is completed. To do. After the processing of the thawing determination process is completed, the ice in the drain system D is in a thawed state, so the flow returns to the flow shown in FIG. 3A again, and the drain valve 26 is normally controlled. (Step S3).

According to the above, the following effects can be obtained in the first embodiment.
When the water in the drain system D is frozen, the thawing determination means 33 determines whether or not the ice has thawed, so that the timing at which water can be discharged from the drain valve 26 can be accurately grasped. Can do. Therefore, even when the water in the drain system D is frozen while the fuel cell FC is stopped, the control of the drain valve 26 can be appropriately started at the next startup.

  Since the thawing determination is made based on the total calorific value Q of the fuel cell FC obtained by parameters detected in a normal fuel cell system such as current I and voltage V, there is no need to provide a dedicated sensor for thawing determination. The number of points can be reduced, and the cost and weight can be reduced.

The present invention is not limited to the first embodiment, and can be implemented in various forms.
In the first embodiment, the calorific value is calculated mainly based on the current and voltage. However, the present invention is not limited to this, and may be calculated based on the temperature of the fuel cell, for example. . However, in this case, since it is necessary to provide a temperature sensor separately in the fuel cell, it is desirable to have the structure as in this embodiment.

[Second Embodiment]
The second embodiment of the present invention will be described below. Since this embodiment is obtained by partially changing the structure of the first embodiment, the same components as those of the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. In the drawings to be referred to, FIG. 4 is a configuration diagram showing a fuel cell system according to the second embodiment, and FIG. 5 is a block diagram showing a configuration of the ECU of FIG.

  As shown in FIG. 4, the fuel cell system S ′ according to the second embodiment uses the temperature in the catch tank 25 instead of the voltmeter 41 and the ammeter 42 provided in the structure of the first embodiment. A temperature sensor (temperature detection means) 44 for detection is provided. In addition, the fuel cell system S ′ is provided with an ECU 3 ′ that performs thawing determination different from that in the first embodiment.

  As shown in FIG. 5, the ECU 3 ′ includes a freezing determination unit 31 and a drain valve control unit 34 having functions similar to those of the first embodiment, and a thawing determination unit 33 ′ having a slightly different function from that of the first embodiment. It consists of and. Hereinafter, only functions different from those of the first embodiment of the decompression determination unit 33 'will be described.

  When the signal sent from the freezing judgment means 31 is a “signal indicating that the water in the drain system D is frozen”, the thawing judgment means 33 ′ refers to the signal from the temperature sensor 44, It has a function of determining that the ice in the drain system D has been thawed. Specifically, the thaw determination means 33 ′ receives a catch signal sent from the temperature sensor 44 when a “signal indicating that the water in the drain system D is frozen” is sent from the freeze judgment means 31. It has a function of determining whether or not the temperature in the tank 25 exceeds a predetermined value, and determining that the ice in the drain system D has been thawed when it is determined that the temperature exceeds the predetermined value. .

  Next, the operation of the ECU 3 '(particularly, the operation of the thawing determination means 33') will be described with reference to FIG. In the drawings to be referred to, FIG. 6 is a flowchart showing the thawing determination of the ECU according to the second embodiment. The operation of the ECU 3 ′ according to the present embodiment is a modification of only the thawing determination step (step S2) in the flowchart of FIG. 3A described in the first embodiment. The description of S1, S3) will be omitted.

  As shown in FIG. 6, in the thawing determination step, first, it is determined whether or not the water in the drain system D is frozen based on the outside air temperature as in the first embodiment (step S11). In step S11, when it is determined that it is frozen (No), it is determined whether or not the current temperature T in the catch tank 25 exceeds a predetermined value T1, so that the inside of the drain system D is determined. It is determined whether or not the ice has been thawed (step S21).

  If it is determined in step S21 that the predetermined value T1 has not been exceeded (No), the processes in steps S11 and S21 are repeated again. If it is determined in step S21 that the predetermined value has been exceeded (Yes), or if it is determined in step S11 that the drain system D is not frozen (Yes), the process proceeds to step S18, and the drain system D It is determined that the ice inside is thawed (or already thawed).

According to the above, the following effects can be obtained in the second embodiment.
Since the temperature near the drain valve 26 is directly detected by the temperature sensor 44, it is possible to make a reliable thawing determination.

The present invention is not limited to the second embodiment, and can be implemented in various forms.
In the second embodiment, the temperature in the catch tank 25 is detected. However, the present invention is not limited to this. For example, the temperature in the drain line 25a or the drain valve 26 may be detected. Good.

[Third Embodiment]
The third embodiment of the present invention will be described below. Since this embodiment is obtained by partially changing the structure of the first embodiment, the same components as those of the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. In the drawings to be referred to, FIG. 7 is a configuration diagram showing a fuel cell system according to a third embodiment, and FIG. 8 is a block diagram showing a configuration of the ECU of FIG. In the third embodiment, it is assumed that the drain valve 26 has a structure in which water does not accumulate therein (a structure in which the drain valve 26 does not stop opening due to freezing).

  As shown in FIG. 7, the fuel cell system S ″ according to the third embodiment is arranged on the downstream side of the drain valve 26 instead of the voltmeter 41 and the ammeter 42 provided in the structure of the first embodiment. A hydrogen sensor (reactive gas detection means) 45 is provided, and the fuel cell system S ′ is provided with an ECU 3 ″ for performing a thawing determination different from that of the first embodiment.

  As shown in FIG. 8, the ECU 3 ″ includes a freezing determination means 35, a thawing determination means 36, and a drain valve control means 37 that are slightly different in function from the first embodiment.

  The freezing determination means 35 has a function similar to that of the first embodiment in which it is determined whether or not the water in the drain system D is frozen based on the outside air temperature, and the result is output to the thawing determination means 36. ing. In addition, the freezing determination means 35 has a function different from that of the first embodiment in that when it is determined that the water in the drain system D is frozen, the signal is also output to the drain valve control means 37. Have.

  The thawing determination means 36 refers to the signal from the hydrogen sensor 45 when the signal sent from the freezing determination means 35 is a “signal indicating that the water in the drain system D is frozen”. It has a different function from the first embodiment, such as determining whether or not the ice in the system D has been thawed. Specifically, the thawing determination means 36 receives the hydrogen gas sent from the hydrogen sensor 45 when a “signal indicating that the water in the drain system D is frozen” is sent from the freezing judgment means 35. A function of determining whether or not the ice in the drain system D has been thawed when it is determined whether or not the amount of hydrogen (hydrogen concentration) exceeds a predetermined value and the hydrogen concentration exceeds a predetermined value ing. Here, the reason why the thawing determination can be made based on the hydrogen concentration is that when the hydrogen concentration is equal to or lower than the predetermined value, it is recognized that the hydrogen gas is not normally discharged from the drain valve 26, and the catch tank 25 It can be determined that the drain line 25a is closed due to freezing, and if the hydrogen concentration exceeds a predetermined value, it is recognized that the hydrogen gas is normally discharged from the drain valve 26, and the catch tank This is because it can be determined that the ice that has closed the drain line 25 and the drain line 25a has thawed.

  The thawing determination means 36 also thaws the ice in the drain system D even when the signal sent from the freezing determination means 35 is a “signal indicating that the water in the drain system D is not frozen”. It has the same function as that of the first embodiment, such as determining that it has been performed. The thawing determination means 36 does not send a signal to the drain valve control means 37 while determining that the ice in the drain system D has not been thawed, but only when it is determined that the ice has been thawed. It also has a function similar to that of the first embodiment, such as outputting a signal indicating the above to the drain valve control means 37.

  The drain valve control means 37 has the same function as that of the first embodiment, such as opening the drain valve 26 under normal control when a “signal indicating that thawing has been performed” is sent from the thawing determination means 36. Have. Further, the drain valve control means 37 is configured to open the drain valve 26 when a “signal indicating that the water in the drain system D is frozen” is sent from the freezing judgment means 35. It also has a function (drain valve opening means) different from the embodiment.

  Next, the operation of the ECU 3 ″ will be described with reference to FIG. 9. In the referenced drawings, FIG. 9 is a flowchart showing the defrosting determination of the ECU according to the third embodiment. The operation of the ECU 3 ″ is a modification of only the thawing determination step (step S2) in the flowchart of FIG. 3A described in the first embodiment, so that the other operations (steps S1 and S3) are described. Will be omitted.

  As shown in FIG. 9, in the thawing determination step, it is first determined whether or not the water in the drain system D is frozen based on the outside air temperature as in the first embodiment (step S11). If it is determined in step S11 that it is frozen (No), the flow proceeds to step S31, and the drain valve 26 is opened. After step S31, the process proceeds to step S32, and it is determined whether or not the ice in the drain system D has been thawed by determining whether or not the hydrogen concentration detected by the hydrogen sensor 45 exceeds a predetermined value. (Step S32).

  If it is determined in step S32 that the predetermined value is not exceeded (No), the processes of steps S11, S31, and S32 are repeated again. If it is determined in step S32 that the predetermined value has been exceeded (Yes), or if it is determined in step S11 that the drain system D is not frozen (Yes), the process proceeds to step S18, and the drain system D It is determined that the ice inside is thawed (or already thawed).

According to the above, the following effects can be obtained in the third embodiment.
Since it is determined that the ice blocking the inside of the drain system D has been thawed by discharging a predetermined amount of hydrogen gas from the drain valve 26, a reliable thawing determination can be performed. Further, since the thawing determination is performed by monitoring the communication state of the drain system D in this manner, for example, even if the ice in the drain system D is not completely melted, it can be drained through a hole through which hydrogen gas flows, and the drain valve 26 can be quickly sunk. Can be normally controlled.

In addition, this invention is implemented in various forms, without being limited to each said embodiment (1st Embodiment-3rd Embodiment).
In each of the above embodiments, it is determined whether or not the water in the drain system D is frozen based on the signal detected by the outside air temperature sensor 43, but the present invention is not limited to this. Freezing of water in the drain system D may be determined based on a signal from a temperature sensor that detects the temperature.

It is a lineblock diagram showing the fuel cell system concerning a 1st embodiment. It is a block diagram which shows the structure of ECU of FIG. The flowchart (a) showing the operation of the ECU until the drain valve is normally controlled, the flowchart (b) showing the operation of the ECU based on the subroutine of FIG. 3 (a), and the heat generation amount of FIG. 3 (b) are integrated. It is the map (c) referred in a step. It is a block diagram which shows the fuel cell system which concerns on 2nd Embodiment. It is a block diagram which shows the structure of ECU of FIG. It is a flowchart which shows the thawing | decompression determination of ECU which concerns on 2nd Embodiment. It is a block diagram which shows the fuel cell system which concerns on 3rd Embodiment. It is a block diagram which shows the structure of ECU of FIG. It is a flowchart which shows the thawing | decompression determination of ECU which concerns on 3rd Embodiment.

Explanation of symbols

1 Air supply system 2 Hydrogen supply system 3 ECU
25 Catch tank (water reservoir)
25a Drain line 26 Drain valve 31 Freezing determination means 32 Heat generation amount integration means 33 Defrosting determination means 34 Drain valve control means 41 Voltmeter 42 Ammeter 43 Outside temperature sensor D Drain system FC Fuel cell S Fuel cell system

Claims (4)

A fuel cell that generates power by reacting reactive gases; and
A water reservoir for storing water generated by power generation of the fuel cell;
A drain valve for discharging water from the water reservoir, and a fuel cell system comprising:
Freezing determination means for determining whether water in the water reservoir and the drain valve is frozen at the time of starting the fuel cell;
When the freezing determination means determines that the ice is frozen, the ice in the water reservoir and the drain valve is thawed based on a parameter that changes in relation to the thawing of ice in the water reservoir or the drain valve. A fuel cell system, further comprising: a thawing judgment means for judging whether or not. The fuel cell system according to claim 1,
A calorific value integrating means for integrating the calorific value from the start of the fuel cell to the present as the parameter,
The thawing judging means judges that the ice in the water reservoir and the drain valve has been thawed when the calorific value accumulated by the calorific value accumulating means exceeds a predetermined value. . The fuel cell system according to claim 1,
A temperature detecting means for detecting the temperature in the water reservoir or the drain valve as the parameter;
The thawing determination means determines that the ice in the water reservoir and the drain valve has been thawed when the temperature detected by the temperature detection means exceeds a predetermined value. The fuel cell system according to claim 1,
The water reservoir is provided in a reaction gas flow path serving as a passage for the reaction gas,
Drain valve opening means for opening the drain valve when starting the fuel cell;
Reaction gas detection means for detecting, as the parameter, the amount of the reaction gas discharged from the drain valve opened by the drain valve opening means,
The thawing determination means determines that the ice in the water reservoir and the drain valve has been thawed when the amount of the reaction gas detected by the reaction gas detection means exceeds a predetermined value. Fuel cell system.

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