JP2008282794A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent failure at the time of starting a fuel cell system by exactly estimating temperature of a drain valve which permits or interrupts discharge of moisture in the fuel cell system. <P>SOLUTION: A fuel cell system 1 including: a fuel cell 2; a drain passage 47 arranged to discharge moisture in the fuel cell 2; a drain valve 46 arranged to permit or interrupt discharge of moisture in the drain passage 47; a temperature estimation device 5 arranged to estimate the temperature of the drain valve 46; and a fuel cell temperature detection device 21 arranged to detect the temperature in the fuel cell 2, wherein the temperature estimation device 5 has control data for specifying correlation between the temperature in the fuel cell 2 and the temperature of the drain valve 46 and estimates the temperature of the drain valve 46 on the basis of the temperature in the fuel cell 2 detected by the fuel cell detection device 21 and the control data. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel cell system.

  Currently, a fuel cell system including a fuel cell that receives a supply of reaction gas (fuel gas and oxidizing gas) and generates electric power has been proposed and put into practical use. When power is generated by such a fuel cell system, moisture is generated inside the fuel cell by an electrochemical reaction. For example, the generated water is discharged to the outside of the fuel cell together with the fuel off-gas, and is discharged to the outside through a gas-liquid separator and a drain valve provided in the fuel gas circulation passage. Since moisture exists in the fuel cell system internal parts (for example, drainage valves) in this way, if the fuel cell system is stopped for a long time in a low temperature environment such as below freezing point, the parts freeze, The normal start-up of the fuel cell system may be hindered.

In order to prevent the moisture in the system from freezing and prevent the occurrence of malfunctions at the start of the fuel cell system, the temperature of the parts in the fuel cell system where moisture exists is estimated, and the estimated temperature A technique for avoiding freezing of moisture by determining whether or not to stop the system based on the above has been proposed (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 2005-267961

  By the way, the technique described in Patent Document 1 estimates the temperature of a component from three parameters of the outside air temperature, the vehicle speed, and the output of the fuel cell, and determines the risk of freezing based on the estimated temperature. When the estimation formula described in this document is adopted, when the output of the fuel cell is zero, the temperature of the component is estimated to be the same as the outside air temperature.

  However, the component temperature after stopping the fuel cell does not immediately become the same as the outside air temperature, and changes according to a predetermined pattern based on the outside air temperature, the system configuration, and the like. In the technique described in Patent Document 1 described above, since the temperature of a component is not estimated in consideration of such a transition pattern, the temperature of the component cannot be accurately estimated after the operation of the fuel cell is stopped. was there.

  The present invention has been made in view of such circumstances, and accurately estimates the temperature of a drain valve that allows or blocks the discharge of moisture in the fuel cell system, and suppresses the occurrence of problems at the start of the fuel cell system. The purpose is to do.

  In order to achieve the above object, a fuel cell system according to the present invention allows a fuel cell, a drainage channel for draining moisture in the fuel cell to the outside, and allows or blocks drainage of moisture in the drainage channel. In a fuel cell system comprising a drain valve, temperature estimating means for estimating the temperature of the drain valve, and fuel cell temperature detecting means for detecting the temperature in the fuel cell, the temperature estimating means is a temperature in the fuel cell. Control data for defining the correlation between the temperature of the drain valve and the temperature of the drain valve, and the temperature of the drain valve is estimated based on the temperature in the fuel cell detected by the fuel cell temperature detecting means and the control data .

  As the control data, a temperature difference history map showing a time history of a value (temperature difference) obtained by subtracting the temperature of the drain valve from the temperature in the fuel cell after the operation of the fuel cell is stopped can be adopted. The temperature estimating means estimates the value obtained by subtracting the maximum temperature difference in the temperature difference history map from the temperature in the fuel cell at the next start detected by the fuel cell temperature detecting means as the temperature of the drain valve. be able to.

  If such a configuration is adopted, the temperature of the drain valve is accurately determined based on control data prepared in advance (data defining the correlation between the temperature in the fuel cell and the temperature of the drain valve) and the temperature in the fuel cell. It can be estimated well. In particular, a temperature difference history map showing a time history of a value (temperature difference) obtained by subtracting the temperature of the drain valve from the temperature inside the fuel cell after the fuel cell is stopped is used as control data. By estimating using the maximum value of the temperature difference at, the temperature of the drain valve can be estimated on the safest side. Therefore, it is possible to perform the freezing determination on the safe side, and to effectively suppress the occurrence of problems at the start of the fuel cell system.

  The fuel cell system may include outside air temperature detecting means for detecting the outside air temperature. In such a case, temperature estimation means for estimating the temperature of the drain valve based on the outside air temperature detected by the outside air temperature detection means, the temperature inside the fuel cell detected by the fuel cell temperature detection means, and the control data is employed. be able to.

  As the control data, a temperature difference history map showing a time history of a value (temperature difference) obtained by subtracting the temperature of the drain valve from the temperature inside the fuel cell after the fuel cell operation is stopped is set for each outside air temperature. A difference history map group can be employed. The temperature estimating means selects one temperature difference history map corresponding to the outside air temperature at the next start detected by the outside air temperature detecting means from the temperature difference history map group, and at the next start time detected by the fuel cell temperature detecting means. The value obtained by subtracting the maximum value of the temperature difference in one temperature difference history map from the temperature in the fuel cell at can be estimated as the temperature of the drain valve.

  If such a configuration is adopted, the temperature of the drainage valve can be estimated in consideration of the outside air temperature, so that the temperature can be accurately estimated while reflecting the actual environment.

  The fuel cell system may further comprise a time measuring means for measuring the operation stop time when the fuel cell operation is stopped. In such a case, a temperature estimation unit that estimates the temperature of the drain valve based on the operation stop time measured by the timing unit, the temperature in the fuel cell detected by the fuel cell temperature detection unit, and the control data is adopted. Can do.

  As the control data, a temperature difference history map showing a time history of a value (temperature difference) obtained by subtracting the temperature of the drain valve from the temperature in the fuel cell after the operation of the fuel cell is stopped can be adopted. The temperature estimating means determines a temperature difference corresponding to the operation stop time measured by the time measuring means based on the temperature difference history map, and from the temperature in the fuel cell at the next start detected by the fuel cell temperature detecting means, A value obtained by subtracting the determined temperature difference can be estimated as the temperature of the drain valve.

  By adopting such a configuration, it is possible to estimate the temperature of the drain valve after determining the temperature difference at the estimated time based on the temperature difference history map, so the temperature of the drain valve is not estimated to be lower than necessary, The temperature can be accurately estimated by reflecting the passage of time.

  The fuel cell system may include both an outside air temperature detecting unit that detects an outside air temperature and a time measuring unit that measures an operation stop time when the operation of the fuel cell is stopped. In such a case, based on the outside air temperature detected by the outside air temperature detecting means, the operation stop time measured by the time measuring means, the temperature inside the fuel cell detected by the fuel cell temperature detecting means, and the control data, A temperature estimation means for estimating the temperature can be employed.

  As the control data, a temperature difference history map showing a time history of a value (temperature difference) obtained by subtracting the temperature of the drain valve from the temperature inside the fuel cell after the fuel cell operation is stopped is set for each outside air temperature. A difference history map group can be employed. The temperature estimating means selects one temperature difference history map corresponding to the outside air temperature at the next start detected by the outside air temperature detecting means from the temperature difference history map group, and corresponds to the operation stop time measured by the time measuring means. The temperature difference is determined based on one temperature difference history map, and the value obtained by subtracting the determined temperature difference from the temperature in the fuel cell at the next start detected by the fuel cell temperature detecting means is the temperature of the drain valve. Can be estimated.

  When such a configuration is adopted, the temperature of the drain valve can be estimated in consideration of both the outside air temperature and the operation stop time of the fuel cell, so that the temperature can be estimated with higher accuracy.

  In the fuel cell system, control data including the temperature of the drain valve at the previous stop can be employed. In such a case, the lower value of the temperature in the fuel cell detected by the fuel cell temperature detecting means and the temperature of the drain valve at the previous stop included in the control data is calculated at the time of starting the fuel cell. It is possible to employ a temperature estimating means for setting the initial estimated temperature of the drain valve.

  By adopting such a configuration, the lower one of the temperature in the fuel cell and the temperature of the drain valve at the previous stop can be set as the initial estimated temperature of the drain valve at the start of the fuel cell. . Therefore, even when the fuel cell temperature is lower than the temperature of the drain valve at the previous stop due to the operation stop of the fuel cell for a long time, the temperature of the drain valve can be estimated on the safe side. Therefore, it is possible to perform the freezing determination on the safe side, and to effectively suppress the occurrence of problems at the start of the fuel cell system.

  In the fuel cell system, a refrigerant circulation passage for circulating the refrigerant discharged from the refrigerant outlet of the fuel cell to the refrigerant inlet of the fuel cell, and a drain valve from the vicinity of the refrigerant inlet of the fuel cell in the refrigerant circulation passage And a valve coolant channel for circulating the coolant to the head. In such a case, it is possible to employ temperature estimation means for stopping the update of the initial estimated temperature within a predetermined time until the refrigerant reaches the drain valve from the refrigerant circulation channel via the valve refrigerant channel.

  When such a configuration is adopted, the initial estimated temperature at the time of start-up is updated within a predetermined time after the start of the fuel cell (the time until the refrigerant reaches the drain valve from the refrigerant circulation passage through the valve refrigerant passage). Can be stopped. That is, when estimating the temperature, the delay time until the refrigerant reaches the drain valve can be taken into consideration, so that the temperature can be estimated with higher accuracy.

  In the fuel cell system, a fuel cell temperature detecting means for detecting the temperature of the refrigerant in the vicinity of the refrigerant inlet of the fuel cell in the refrigerant circulation channel as the temperature in the fuel cell can be employed. In such a case, after the lapse of the predetermined time, the drainage after the current time based on the estimated temperature of the drainage valve at the current time and the temperature of the refrigerant detected by the fuel cell temperature detecting means at the time before the predetermined time from the current time. Temperature estimation means for estimating the temperature of the valve can be employed.

  When such a configuration is adopted, the estimated temperature of the drain valve at the present time and the point in time before the present time after the predetermined time until the refrigerant reaches the drain valve from the refrigerant circulation channel via the valve coolant channel. The temperature of the drain valve after the current time can be estimated on the basis of the temperature of the refrigerant detected in step. Therefore, the temperature can be estimated with higher accuracy in consideration of the delay time until the refrigerant reaches the drain valve.

  The fuel cell system may further include an outside air temperature detecting unit that detects the outside air temperature. In such a case, after the predetermined time has elapsed, based on the estimated temperature of the drain valve at the current time and the outside air temperature detected by the outside air temperature detecting means at the current time, the temperature estimating means for estimating the temperature of the drain valve after the current time Can be adopted.

  When such a configuration is adopted, the estimated temperature of the drain valve at the current time and the outside air temperature detected at the current time after the elapse of a predetermined time until the refrigerant reaches the drain valve from the refrigerant circulation channel via the valve coolant channel. , The temperature of the drain valve after the current time can be estimated. Therefore, it is possible to accurately estimate the temperature in consideration of the latest outside air temperature information.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to estimate accurately the temperature of the drain valve that allows or blocks the drainage of water in the fuel cell system, and it is possible to suppress the occurrence of problems at the start of the fuel cell system. .

  Hereinafter, a fuel cell system according to an embodiment of the present invention will be described with reference to the drawings. The fuel cell system according to the present embodiment is a power generation system mounted on a fuel cell vehicle as a moving body.

<First Embodiment>
First, the fuel cell system 1 according to the first embodiment of the present invention will be described with reference to FIGS.

  The fuel cell system 1 according to the present embodiment includes a fuel cell 2 that is supplied with reaction gas (oxidation gas and fuel gas) and generates electric power through an electrochemical reaction, and the fuel cell 2 has air as an oxidation gas ( An oxidizing gas piping system 3 for supplying oxygen), a fuel gas piping system 4 for supplying hydrogen gas as a fuel gas to the fuel cell 2, a control device 5 for integrated control of the entire system, and the like. The fuel cell system 1 includes an outside air temperature sensor 6, and a detection signal from the outside air temperature sensor 6 is input to the control device 5. The outside air temperature sensor 6 is an embodiment of the outside air temperature detecting means in the present invention.

  The fuel cell 2 is formed of, for example, a solid polymer electrolyte type suitable for in-vehicle use or stationary use, and has a stack structure in which a required number of unit cells that generate power upon receiving a reaction gas are stacked. The unit cell constituting the fuel cell stack has an air electrode on one surface of an electrolyte made of an ion exchange membrane, a fuel electrode on the other surface, and a pair of the air electrode and the fuel electrode sandwiched from both sides. Of separators. An oxidizing gas (air) is supplied to an oxidizing gas flow path provided on one side of the separator, and a fuel gas (hydrogen) is supplied to a fuel gas flow path provided on the other separator. An electrochemical reaction is performed in the unit cell that is supplied with the oxidizing gas and the fuel gas, whereby the fuel cell 2 generates electric power.

  Since the electrochemical reaction in the fuel cell 2 is an exothermic reaction, heat is supplied into the fuel cell system 1 according to the output during operation of the fuel cell 2. Therefore, even in a low temperature environment, while the fuel cell 2 is in operation, the temperature of the components in the system is increased by supplying the off-gas and the like heated in the fuel cell 2 to each piping system. Therefore, freezing is normally avoided during operation of the fuel cell 2. The fuel cell system 1 is provided with a refrigerant piping system (not shown). And by circulating a refrigerant | coolant inside the fuel cell 2 using this refrigerant | coolant piping system, the temperature inside the fuel cell 2 is maintained moderately. The temperature in the fuel cell 2 is detected by the temperature sensor 21, and the detected value is input to the control device 5 and used for various controls. The temperature sensor 21 can be provided in the fuel cell 2, for example, but the temperature in the fuel cell may be obtained from the detected value of the temperature sensor provided in the fluid piping flowing out from the fuel cell 2. The temperature sensor 21 is an embodiment of the fuel cell temperature detecting means in the present invention.

  The oxidizing gas piping system 3 includes an air supply passage 31 that supplies the oxidizing gas (air) humidified by the humidifier 30 to the fuel cell 2, and an air drain that guides the oxidizing off-gas discharged from the fuel cell 2 to the humidifier 30. A flow path 32 and an exhaust flow path 33 for guiding the oxidizing off gas from the humidifier 30 to the outside are provided. The air supply passage 31 is provided with a compressor 34 that takes in the oxidizing gas in the atmosphere and pumps it to the humidifier 30. The operation of the compressor 34 is controlled by the control device 5. By the operation of the compressor 34, the oxidizing gas in the atmosphere is taken in through the filter and is pumped to the fuel cell 2. Further, the oxidant off-gas flowing through the air drainage channel 32 is finally discharged into the atmosphere as exhaust gas after the moisture is exchanged by the humidifier.

  The fuel gas piping system 4 includes a hydrogen tank 40 storing high-pressure fuel gas (hydrogen gas), a hydrogen supply passage 41 for supplying the hydrogen gas in the hydrogen tank 40 to the fuel cell 2, and an exhaust from the fuel cell 2. And a circulation channel 42 for returning the hydrogen off-gas generated to the hydrogen supply channel 41. The hydrogen supply channel 41 is provided with a shutoff valve 43 that shuts off or allows the supply of hydrogen gas from the hydrogen tank 40 and a regulator 44 that adjusts the pressure of the hydrogen gas. In the present embodiment, a modulatable pressure regulator 44 that can change the target value of the supply pressure by a step motor is employed. The operations of the shut-off valve 43 and the regulator 44 are controlled by the control device 5.

  A drainage channel 47 is connected to the circulation channel 42 via a gas-liquid separator 45 and an exhaust drainage valve 46. The gas-liquid separator 45 collects moisture from the hydrogen off gas. The exhaust / drain valve 46 operates according to a command from the control device 5 to discharge (purge) moisture collected by the gas-liquid separator 45 and hydrogen off-gas containing impurities in the circulation flow path 42 to the outside. Is. The circulation channel 42 is provided with a hydrogen pump 48 that pressurizes the hydrogen off-gas in the circulation channel 42 and sends it to the hydrogen supply channel 41 side. The gas in the drainage channel 47 is diluted by a diluter (not shown) and merges with the gas in the exhaust channel 33 in the exhaust pipe 49.

  The control device 5 receives control information such as a demand load signal such as an accelerator signal of a vehicle (not shown), various operation signals, detection signals of various sensors such as the outside air temperature sensor 6 and the temperature sensor 21, and the like. Control the operation of various devices. The control device 5 is configured by a computer system (not shown). Such a computer system includes a CPU, ROM, RAM, HDD, input / output interface, display, and the like, and various control operations are realized by the CPU reading and executing various control programs recorded in the ROM. It is like that. Further, the control device 5 has an RTC (Real Time Clock) 5a that can operate upon receiving power supply from the battery. The RTC 5a measures the operation stop time when the operation of the fuel cell 2 is stopped, and is an embodiment of the time measuring means in the present invention.

  For example, the control device 5 controls various components such as the oxidant gas piping system 3, the fuel gas piping system 4, and the refrigerant piping system according to the required output to supply the reaction gas and the refrigerant to the fuel cell 2 to generate power. Do. Further, when the operation of the fuel cell 2 is stopped (when power generation is stopped), the control device 5 temporarily controls the compressor 34, the shut-off valve 43, and the regulator 44 to control the gas (oxidizing gas and hydrogen gas) in the fuel cell 2. ) Is carried out to scavenge the water in the fuel cell 2 to the outside. When scavenging is performed, the water remaining in the fuel cell 2 is discharged to the circulation flow path 42. When the exhaust drain valve 46 is opened, moisture is discharged to the outside of the fuel cell vehicle via the drain passage 47 and the discharge pipe 49.

  In addition, when the operation of the fuel cell 2 is stopped (when power generation is stopped), the control device 5 estimates the temperature of each component constituting the fuel cell system 1 and determines whether each component may freeze during power generation stop. judge. The possibility of freezing is considered to be a part where water is present when the operation is stopped. As an example, there is an exhaust drain valve 46. In the present embodiment, as will be described below, the fuel cell 2 at the next start time detected by the temperature sensor 21 based on control data that defines the correlation between the temperature in the fuel cell 2 and the temperature of the exhaust drain valve 46. The temperature of the exhaust / drain valve 46 is estimated from the internal temperature.

  The control device 5 stores map data as shown in FIG. 2 as control data used for temperature estimation of the exhaust / drain valve 46. FIG. 2 shows a temperature difference curve C (temperature difference) in which a time history of a value (temperature difference) obtained by subtracting the temperature of the exhaust / drain valve 46 from the temperature in the fuel cell 2 during power generation stop of the fuel cell 2 is mapped in advance. (History map), the horizontal axis represents the elapsed time from the power generation stop of the fuel cell 2, and the vertical axis represents the temperature difference.

  During operation of the fuel cell 2, the temperature of the components in the system is higher than the outside air temperature even in a low temperature environment by supplying off-gas etc. heated in the fuel cell 2 to each piping system. It is kept at temperature. The temperature of the exhaust drain valve 46 during operation is lower than the temperature in the fuel cell 2 because the heat is released and the hydrogen off gas and generated water are lowered in the process of reaching the exhaust drain valve 46. That is, during operation of the fuel cell 2, a predetermined temperature difference corresponding to the outside air temperature is generated between the temperature in the fuel cell 2 and the temperature of the exhaust drain valve 46.

  When the operation of the fuel cell 2 is stopped, as shown in FIG. 2, the difference between the temperature in the fuel cell 2 and the temperature of the exhaust drain valve 46 increases for a while immediately after the fuel cell 2 stops generating power, and the predetermined time t0 is reduced. When the time elapses, the maximum value A is reached. Thereafter, the temperature difference gradually decreases. When a sufficiently long time elapses, the temperature in the fuel cell 2 and the temperature of the exhaust / drain valve 46 are both substantially constant with the outside air temperature, and the temperature difference approaches zero.

The shape of the temperature difference curve C changes according to the outside air temperature when the fuel cell 2 stops generating power. FIG. 3 shows four temperature difference curves C1, C2, C3, and C4 as an example. The temperature difference curves C1, C2, C3 and C4 are for the cases where the outside air temperatures are T ₁ , T ₂ , T ₃ and T ₄ (T ₁ > T ₂ > T ₃ > T ₄ ), respectively. As described above, the lower the outside air temperature, the larger the difference between the temperature in the fuel cell 2 and the temperature of the exhaust / drain valve 46. At any outside air temperature, the temperature difference is equal to a predetermined time after power generation is stopped. At that point, the maximum value is reached. However, the elapsed time to reach the maximum value is slightly different depending on the outside temperature. The maximum value of the temperature difference in the temperature difference curve is larger when the outside air temperature is lower.

  The control device 5 determines the temperature of the exhaust drain valve 46 based on the control data (temperature difference curve) as shown in FIGS. 2 and 3 and the temperature in the fuel cell 2 at the next start time detected by the temperature sensor 21 and the like. Is estimated. That is, the control device 5 functions as an embodiment of the temperature estimation means in the present invention.

In the simplest first estimation method, a temperature difference curve (C4 in FIG. 3) at the assumed coldest outside air temperature (for example, T ₄ ) is used as control data. The control device 5 subtracts the maximum value of the temperature difference in the temperature difference curve from the temperature in the fuel cell 2 at the time of the next start detected by the temperature sensor 21 and the like, and the value calculated as a result of the exhaust drain valve 46 Estimated temperature. For example, if the detected value of the temperature sensor 21 is S1 and the maximum value of the temperature difference curve C4 is A4, the estimated temperature T _E of the exhaust / drain valve 46 is calculated by the equation “T _E = S1-A4”. In this way, the estimated value of the lowest temperature that can be taken in the assumed conditions is adopted.

Further, since the fuel cell system 1 includes the outside air temperature sensor 6, another estimation method can be used based on the detection value of the outside air temperature sensor 6. In the second estimation method, a plurality of temperature difference curves (temperature difference history map group) as shown in FIG. 3 are used as control data. First, the control device 5 selects the most appropriate one from a plurality of temperature difference curves based on the outside air temperature at the next start detected by the outside air temperature sensor 6. For example, the outside air temperature is, if T _2, to select the temperature difference curve C2. That is, one temperature difference curve corresponding to the outside air temperature is selected from a plurality of temperature difference curves. Then, as in the first estimation method, the maximum value of the temperature difference in the selected temperature difference curve C2 is subtracted from the temperature in the fuel cell 2 at the next start detected by the temperature sensor 21 and the like, and the result is calculated. The calculated value is estimated as the temperature of the exhaust / drain valve 46. For example, if the detected value of the temperature sensor 21 is S2 and the peak value of the temperature difference curve C2 is A2, the estimated temperature T _E of the exhaust / drain valve 46 is calculated by the equation “T _E = S2-A2”.

In this way, the estimated value of the lowest temperature that can be taken under the outside air temperature at the next start-up is adopted. Therefore, it is possible to obtain an estimated value that is on the safe side from the viewpoint of freeze prevention, and it is possible to perform temperature estimation with higher accuracy based on the outside air temperature. In FIG. 3, four temperature difference curves C1, C2, C3, and C4 when the outside air temperatures are T ₁ , T ₂ , T ₃ , and T ₄ are used as control data. Whether to create a temperature difference curve for the outside air temperature can be appropriately set according to the assumed operating temperature environment of the fuel cell system 1.

Moreover, since the fuel cell system 1 includes the RTC 5a, another estimation method can be used. In the third estimation method, unlike the first and second estimation methods, the elapsed time (operation stop time) from when the fuel cell 2 is stopped to the next start is measured by the RTC 5a, and the control device 5 The temperature difference corresponding to the operation stop time is obtained from the temperature difference curve, and used instead of the maximum value used in the first and second estimation methods. As to which temperature difference curve is used, the temperature difference curve at the lowest outside air temperature may be used as in the first estimation method, and the temperature difference curve corresponding to the outside air temperature is selected as in the second estimation method. May be. Also, the temperature difference curve can be selected by other methods. Then, similarly to the first and second estimation methods, the temperature difference determined from the operation stop time and the temperature difference curve is subtracted from the temperature in the fuel cell 2 at the next start detected by the temperature sensor 21 or the like, The calculated value is estimated as the temperature of the exhaust / drain valve 46. For example, if the detected value of the temperature sensor 21 is S3, the temperature difference curve selected by the outside air temperature is C3, the operation stop time is t1, and the temperature difference corresponding to the operation stop time t1 on the temperature difference curve C3 is A3. For example, the estimated temperature T _E of the exhaust / drain valve 46 is calculated by the formula “T _E = S3−A3”.

  In this way, after the temperature difference curve is determined based on the outside air temperature or the like, the temperature can be accurately estimated based on the temperature difference curve and the operation stop time. Therefore, the freeze determination can be performed with high accuracy. In addition, if a temperature difference curve in a low temperature environment is selected, an estimated value that is on the safe side from the viewpoint of freeze prevention can be obtained, and freezing determination can be performed on the safe side.

  The control device 5 determines whether the exhaust drain valve 46 is frozen based on the temperature of the exhaust drain valve 46 estimated by the above methods. For example, a determination value for freezing determination such as 0 ° C. (or a temperature slightly higher than 0 ° C. with a margin) is set, and it is determined that the exhaust / drain valve 46 freezes when the estimated temperature falls below the determination value. To do. When the exhaust drain valve 46 is in a frozen state, even if the fuel cell system 1 is started, since the frozen exhaust drain valve 46 does not move immediately, the exhaust drain valve 46 cannot be operated properly. The purge operation cannot be performed. In other words, when the exhaust drain valve 46 is in a frozen state, the normal start of the fuel cell system 1 is prevented as it is. Therefore, the control device 5 can perform various freeze prevention processes in order to suppress such a malfunction at the start of the fuel cell system 1. For example, it is conceivable to complete the drainage of water before reaching the freezing temperature, or to supply heat to the exhaust / drain valve 46 so that the temperature does not decrease to the freezing temperature.

  In the fuel cell system 1 according to the embodiment described above, the control device 5 has in advance control data that defines the correlation between the temperature in the fuel cell 2 and the temperature of the exhaust drainage valve 46, and this control data, The temperature of the exhaust / drain valve 46 can be accurately estimated based on the temperature in the fuel cell 2 at the next start. In particular, it is possible to estimate the drain valve temperature on the safest side by estimating a value obtained by subtracting the maximum value on the temperature difference curve from the temperature in the fuel cell 2 at the next start as the temperature of the exhaust drain valve 46. it can. Therefore, it is possible to perform the freezing determination on the safe side, and to effectively suppress the occurrence of problems at the start of the fuel cell system.

  Further, in the fuel cell system 1 according to the embodiment described above, a temperature difference curve corresponding to the outside air temperature at the next start detected by the outside air temperature sensor 6 is selected, and exhaust is performed based on the selected temperature difference curve. The temperature of the drain valve 46 can also be estimated. Thereby, the temperature of the exhaust / drain valve 46 can be estimated in consideration of the outside air temperature, and the temperature can be estimated with higher accuracy reflecting the actual environment.

  Further, in the fuel cell system 1 according to the embodiment described above, the temperature difference corresponding to the operation stop time measured by the RTC 5a can be obtained from the temperature difference curve, and the temperature of the exhaust / drain valve 46 can be estimated. Thereby, the temperature of the exhaust / drain valve 46 can be estimated in consideration of the operation stop time of the fuel cell 2, and the temperature can be estimated more accurately.

  In the present embodiment, the temperature difference curve (temperature difference history map) as the control data is stored in the control device 5. However, for example, each temperature difference as in the first and second estimation methods is shown. When only the maximum value in the curve is used, only this maximum value can be stored in the control device 5 as control data.

Second Embodiment
Subsequently, a fuel cell system 10 according to a second embodiment of the present invention will be described with reference to FIGS. 4 and 5. The fuel cell system 10 according to the present embodiment changes the configuration of the control device of the fuel cell system 1 according to the first embodiment, and has a flow path for circulating the refrigerant from the refrigerant piping system to the exhaust / drain valve 46. The other configurations are substantially the same. For this reason, different configurations will be mainly described, and overlapping configurations will be denoted by the same reference numerals as those in the first embodiment, and detailed description thereof will be omitted.

  Initially, the structure of the fuel cell system 10 which concerns on this embodiment is demonstrated using FIG. The fuel cell system 10 includes a fuel cell 2, an oxidizing gas piping system 3, a fuel gas piping system 4, a control device 50, and an outside air temperature sensor 6 (outside air temperature detecting means). And a refrigerant piping system 7 for circulating the refrigerant, and a valve refrigerant flow path 8 for circulating the refrigerant from the refrigerant piping system 7 to the exhaust drain valve 46. Since the configurations of the fuel cell 2, the oxidizing gas piping system 3, the fuel gas piping system 4, and the outside air temperature sensor 6 are substantially the same as the configurations in the first embodiment, detailed description thereof is omitted.

  The refrigerant piping system 7 is for maintaining the operating temperature in the fuel cell 2 in an appropriate temperature range. As shown in FIG. 4, the refrigerant (cooling water or the like) discharged from the refrigerant outlet of the fuel cell 2. Is circulated to the refrigerant inlet of the fuel cell 2, a refrigerant pump 71 for circulating the refrigerant, a radiator 72 and a cooling fan 73 for cooling the high-temperature refrigerant discharged from the fuel cell 2. And a temperature sensor 74 for detecting the temperature of the refrigerant in the vicinity of the refrigerant inlet of the fuel cell 2 in the refrigerant circulation passage 70. By controlling the operation of the refrigerant pump 71 and the cooling fan 73 by the control device 50, the temperature and flow rate of the refrigerant in the refrigerant circulation passage 70 are adjusted.

  In the present embodiment, it is assumed that the temperature of the refrigerant in the vicinity of the refrigerant inlet of the fuel cell 2 in the refrigerant circulation passage 70 substantially matches the temperature in the fuel cell 2, and the temperature of the refrigerant detected by the temperature sensor 74 is assumed. Is the temperature in the fuel cell 2. That is, the temperature sensor 74 functions as an embodiment of the fuel cell temperature detection means in the present invention. The value detected by the temperature sensor 74 is input to the control device 50 and used for various controls.

  In the vicinity of the refrigerant inlet of the fuel cell 2 in the refrigerant circulation channel 70 (downstream of the temperature sensor 74), as shown in FIG. 4, a valve refrigerant that circulates the refrigerant from the refrigerant circulation channel 70 to the exhaust drain valve 46. A flow path 8 is connected. A part of the refrigerant circulating in the refrigerant circulation channel 70 flows into the valve refrigerant channel 8 via the refrigerant inlet 81 connected to the refrigerant circulation channel 70 in the vicinity of the refrigerant inlet of the fuel cell 2. . Thereafter, the refrigerant flows through the valve refrigerant flow path 8, passes through the exhaust drain valve 46, and is returned to the refrigerant circulation flow path 70 via the refrigerant outlet 82 on the downstream side of the refrigerant inlet 81. Become. By controlling the operation of the refrigerant pump 71 and the cooling fan 73 by the control device 50, the temperature and flow rate of the refrigerant in the valve refrigerant flow path 8 are adjusted.

  The control device 50 is configured by a computer system as in the first embodiment, and includes a required load signal such as a vehicle accelerator signal, various operation signals, detection signals from various sensors such as the outside air temperature sensor 6 and the temperature sensor 74, In response to the control information, the operation of various devices in the system is controlled.

  The control device 50 according to the present embodiment includes specific control data and the temperature detected by the temperature sensor 74 at the time of starting (the temperature of the refrigerant in the vicinity of the refrigerant inlet of the fuel cell 2 in the refrigerant circulation passage 70 = the temperature in the fuel cell 2). ) And the outside air temperature detected by the outside air temperature sensor 6, the temperature of the exhaust / drain valve 46 at the time of starting is estimated. That is, the control device 50 functions as an embodiment of the temperature estimation means in the present invention. The control device 50 stores information relating to the temperature (estimated temperature) of the exhaust / drain valve 46 at the previous stop as control data, and uses this information for estimating the temperature of the exhaust / drain valve 46 at the start.

  Next, a method for estimating the temperature of the exhaust / drain valve 46 by the control device 50 of the fuel cell system 10 according to the present embodiment will be described using the flowchart of FIG.

  First, the control device 50 determines whether or not an ignition switch (not shown) has been turned ON (start determination step: S1), and when it is determined that the switch has been turned ON, when the exhaust drain valve 46 is started. The temperature (initial temperature) is estimated (initial temperature estimation step: S2). In the initial temperature estimation step S2, the control device 50 selects either the temperature detected by the temperature sensor 74 (the temperature in the fuel cell 2) or the temperature of the exhaust drain valve 46 at the previous stop included in the control data. The lower value is set as the initial estimated temperature of the exhaust / drain valve 46.

  Next, the control device 50 starts from the operation start time of the refrigerant pump 71 of the refrigerant piping system 7 until the time when the refrigerant reaches the exhaust / drain valve 46 from the refrigerant circulation passage 70 via the valve refrigerant passage 8. It is determined whether or not a predetermined time (hereinafter referred to as “delay time”) has passed (time determination step: S3). When it is determined that the delay time has not elapsed in the time determination step S3, the control device 50 stops the temperature estimation of the exhaust / drain valve 46 (maintains the initial estimated temperature in the initial temperature estimation step S2) (initially). Temperature maintenance step: S4).

  On the other hand, when it is determined that the delay time has elapsed in the time determination step S3, the control device 50 estimates the temperature of the exhaust drainage valve 46 at the current time and the temperature detected by the temperature sensor 74 at the time before the current delay time. Based on the outside air temperature detected by the outside air temperature sensor 6 at the present time, the temperature of the exhaust drain valve 46 after the current time is estimated (temperature estimation step: S5).

In the temperature estimation step S5, the control device 50 calculates the estimated temperature of the exhaust / drain valve 46 using the following differential equation (A). In equation (A), Δt is the delay time, T _E (t) is the estimated temperature of the exhaust drain valve 46 at the current time, and T _FC (t−Δt) is detected by the temperature sensor 74 at the time before the current delay time. _TC (t) is the outside air temperature detected by the outside air temperature sensor 6 at the present time, a is the temperature of the refrigerant in the refrigerant circulation passage 70 in the vicinity of the refrigerant inlet of the fuel cell 2 = the temperature inside the fuel cell 2 a And b each represent a constant (> 0). In the formula (A), the first term on the right side means a term related to heating of the exhaust drainage valve 46, and the second term on the right side means a term related to cooling of the exhaust drainage valve 46.

Subsequently, the control device 50 determines whether or not the estimated temperature T _E of the exhaust / drain valve 46 calculated in the temperature estimation step S5 is equal to or higher than a predetermined temperature T ₀ (for example, zero degrees Celsius) (freezing determination step: S6). . If the controller 50 determines in the freezing determination step S6 that the estimated temperature T _E is lower than the predetermined temperature T ₀ , the control device 50 determines that the exhaust drain valve 46 is in a frozen state and returns to the temperature estimating step S5. Then, the temperature estimation of the exhaust / drain valve 46 is continued. Even when the exhaust drain valve 46 is in a frozen state, the exhaust drain valve 46 is gradually heated by the refrigerant supplied from the refrigerant circulation channel 70 to the exhaust drain valve 46 via the valve coolant channel 8. On the other hand, when determining that the estimated temperature T _E is equal to or higher than the predetermined temperature T ₀ in the freezing determination step S6, the control device 50 ends the above-described series of steps relating to the temperature estimation of the exhaust / drain valve 46.

  In the fuel cell system 10 according to the embodiment described above, the lower value of the temperature detected by the temperature sensor 74 and the temperature of the exhaust / drain valve 46 at the previous stop is calculated as the exhaust / drainage at the start. The initial estimated temperature of the valve 46 can be used. Therefore, even when the temperature of the fuel cell 2 becomes lower than the temperature of the exhaust drain valve 46 at the previous stop due to the operation stop of the fuel cell 2 for a long time, the temperature of the exhaust drain valve 46 is kept on the safe side. Can be estimated. Therefore, it is possible to perform the freezing determination on the safe side, and it is possible to effectively suppress the occurrence of problems when the fuel cell system 10 is started.

  In the fuel cell system 10 according to the embodiment described above, the refrigerant reaches the exhaust / drain valve 46 from the refrigerant circulation passage 70 via the valve refrigerant passage 8 for a predetermined time after the start of the refrigerant pump 71. The update of the initial estimated temperature can be stopped within the delay time). Further, after the lapse of the delay time, based on the estimated temperature of the exhaust drainage valve 46 at the current time, the temperature detected by the temperature sensor 74 at the time before the delay time, and the outside air temperature detected at the current time, The temperature of the later exhaust / drain valve 46 can be estimated. Therefore, the temperature can be estimated with higher accuracy in consideration of the delay time until the refrigerant reaches the exhaust / drain valve 46 and the latest outside air temperature information.

  In each of the above embodiments, the temperature of the exhaust / drain valve 46 is estimated and the determination of freezing is performed. However, the temperatures of the other components disposed in the circulation channel 42 and the drain channel 47 are set as above. The freezing determination may be performed by estimating by such a method. In addition to these, it is also possible to estimate the temperature of other components in which moisture exists by the above-described method and perform the freezing determination.

  Further, in each of the above embodiments, the example in which the fuel cell system according to the present invention is mounted on the fuel cell vehicle has been shown. However, the present invention is applied to various moving bodies (robots, ships, aircrafts, etc.) other than the fuel cell vehicle. Such a fuel cell system can also be mounted. Further, the fuel cell system according to the present invention may be applied to a stationary power generation system used as a power generation facility for a building (house, building, etc.).

1 is a configuration diagram of a fuel cell system according to a first embodiment of the present invention. 2 is a temperature difference history map that defines the correlation between the temperature in the fuel cell after power generation is stopped in the fuel cell system shown in FIG. 1 and the temperature of the exhaust drain valve. It is a temperature difference log | history map group which prescribes | regulates the correlation with the temperature in the fuel cell after the power generation stop in different external temperature, and the temperature of an exhaust drainage valve. It is a block diagram of the fuel cell system which concerns on 2nd Embodiment of this invention. 3 is a flowchart for explaining a method for estimating the temperature of an exhaust / drain valve by the control device of the fuel cell system shown in FIG. 1.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 * 10 ... Fuel cell system, 2 ... Fuel cell, 5.50 ... Control apparatus (temperature estimation means), 5a ... RTC (time measuring means), 6 ... Outside temperature sensor (outside temperature detection means), 8 ... Refrigerant for valve Flow path, 21 · 74 ... temperature sensor (fuel cell temperature detecting means), 46 ... exhaust drain valve (drain valve), 47 ... drain channel, 70 ... refrigerant circulation channel, A, A2, A4 ... maximum temperature difference Value, A3: Temperature difference corresponding to the operation stop time, C, C1, C2, C3, C4 ... Temperature difference curve (control data, temperature difference history map), t1: Operation stop time.

Claims (12)

A fuel cell, a drainage channel for draining moisture in the fuel cell to the outside, a drainage valve for allowing or blocking drainage of moisture in the drainage channel, and a temperature estimation means for estimating the temperature of the drainage valve; And a fuel cell temperature detecting means for detecting the temperature in the fuel cell,
The temperature estimation means has control data defining a correlation between the temperature in the fuel cell and the temperature of the drain valve, the temperature in the fuel cell detected by the fuel cell temperature detection means, and the control The temperature of the drain valve is estimated based on the data,
Fuel cell system. The control data is a temperature difference history map showing a time history of a temperature difference obtained by subtracting the temperature of the drain valve from the temperature in the fuel cell after the operation of the fuel cell is stopped.
The temperature estimation means obtains a value obtained by subtracting the maximum value of the temperature difference in the temperature difference history map from the temperature in the fuel cell at the next start detected by the fuel cell temperature detection means. Which is
The fuel cell system according to claim 1. An outside air temperature detecting means for detecting the outside air temperature,
The temperature estimating means estimates the temperature of the drain valve based on the outside air temperature detected by the outside air temperature detecting means, the temperature inside the fuel cell detected by the fuel cell temperature detecting means, and the control data. To do,
The fuel cell system according to claim 1. The control data is a temperature difference obtained by setting a temperature difference history map showing the time history of the temperature difference obtained by subtracting the temperature of the drain valve from the temperature in the fuel cell after the operation of the fuel cell is stopped for each outside air temperature. A history map group,
The temperature estimating means selects one temperature difference history map corresponding to the outside air temperature at the next start detected by the outside air temperature detecting means from the temperature difference history map group, and next time detected by the fuel cell temperature detecting means. A value obtained by subtracting the maximum value of the temperature difference in the one temperature difference history map from the temperature in the fuel cell at the time of starting is estimated as the temperature of the drain valve.
The fuel cell system according to claim 3. When the operation of the fuel cell is stopped, comprising a time measuring means for measuring the operation stop time,
The temperature estimating means estimates the temperature of the drain valve based on the operation stop time measured by the time measuring means, the temperature in the fuel cell detected by the fuel cell temperature detecting means, and the control data. Is,
The fuel cell system according to claim 1. The control data is a temperature difference history map showing a time history of a temperature difference obtained by subtracting the temperature of the drain valve from the temperature in the fuel cell after the operation of the fuel cell is stopped.
The temperature estimating means determines a temperature difference corresponding to the operation stop time measured by the time measuring means on the basis of the temperature difference history map, and the temperature estimating means detects the temperature difference in the fuel cell at the next start detected by the fuel cell temperature detecting means. A value obtained by subtracting the determined temperature difference from the temperature is estimated as the temperature of the drain valve.
The fuel cell system according to claim 5. An outside air temperature detecting means for detecting the outside air temperature;
Time measuring means for measuring the operation stop time when the operation of the fuel cell is stopped;
With
The temperature estimating means includes an outside air temperature detected by the outside air temperature detecting means, an operation stop time measured by the time measuring means, a temperature inside the fuel cell detected by the fuel cell temperature detecting means, and the control data. The temperature of the drain valve is estimated based on
The fuel cell system according to claim 1. The control data is a temperature difference obtained by setting a temperature difference history map showing the time history of the temperature difference obtained by subtracting the temperature of the drain valve from the temperature in the fuel cell after the operation of the fuel cell is stopped for each outside air temperature. A history map group,
The temperature estimating means selects one temperature difference history map corresponding to the outside air temperature at the next start detected by the outside air temperature detecting means from the temperature difference history map group, and sets the operation stop time measured by the time measuring means. A value obtained by determining the corresponding temperature difference based on the one temperature difference history map, and subtracting the determined temperature difference from the temperature in the fuel cell at the next start detected by the fuel cell temperature detecting means. Is the temperature of the drain valve,
The fuel cell system according to claim 7. The control data includes the temperature of the drain valve at the previous stop,
The temperature estimation means is the lower one of the temperature in the fuel cell detected by the fuel cell temperature detection means and the temperature of the drain valve at the previous stop included in the control data, The initial estimated temperature of the drain valve at the start of the fuel cell,
The fuel cell system according to claim 1. A refrigerant circulation passage for circulating the refrigerant discharged from the refrigerant outlet of the fuel cell to the refrigerant inlet of the fuel cell;
A refrigerant passage for a valve for circulating the refrigerant from the vicinity of the refrigerant inlet of the fuel cell of the refrigerant circulation passage to the drain valve,
The temperature estimating means stops the update of the initial estimated temperature within a predetermined time until the refrigerant reaches the drain valve from the refrigerant circulation flow path via the valve refrigerant flow path.
The fuel cell system according to claim 9. The fuel cell temperature detecting means detects the temperature of the refrigerant in the vicinity of the refrigerant inlet of the fuel cell in the refrigerant circulation channel as the temperature in the fuel cell,
The temperature estimating means is based on the estimated temperature of the drain valve at the current time after the predetermined time has elapsed and the temperature of the refrigerant detected by the fuel cell temperature detecting means at the time before the predetermined time from the current time. The temperature of the drain valve later is estimated,
The fuel cell system according to claim 10. An outside air temperature detecting means for detecting the outside air temperature,
The temperature estimating means calculates the temperature of the drain valve after the present time based on the estimated temperature of the drain valve at the present time and the outside air temperature detected by the outside air temperature detecting means at the present time after the predetermined time has elapsed. Is an estimate,
The fuel cell system according to claim 10 or 11.

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