JP5491564B2 - Control method of fuel cell system - Google Patents

Description

  The present invention relates to a control method for a fuel cell system including fuel cells.

  Conventionally, in order to prevent unburned gas (unreacted fuel) discharged from fuel cells from being discharged to the outside, before the unburned gas discharged from the fuel cell is discharged to the outside, catalytic combustion system There is known a fuel cell system that burns unburned gas using a burner.

JP 2002-042851 A

  However, the fuel cell system does not control the amount of fuel or oxidant supplied even though the amount of fuel consumed in the fuel cell changes according to the amount of power consumed. For this reason, when the fuel consumed in the fuel battery cell is small, a large amount of unburned gas is burned by the burner. As a result, unburned gas is not discharged to the outside, but there is a problem that fuel is wasted and the fuel consumption efficiency is deteriorated.

  Therefore, in view of such problems, it is an object of the present invention to improve fuel consumption efficiency in a fuel cell system that extracts electric power from fuel cells.

  The control method of the fuel cell system of the present invention made to achieve the above object includes a fuel cell (21) that generates electric power by chemically reacting a fuel and an oxidant via an electrolyte, and the fuel cell. Fuel supply means (13, 14) for supplying fuel to the negative electrode of the cell (21), oxidant supply means (11, 12) for supplying oxidant to the positive electrode of the fuel cell (21), and the fuel cell The spent fuel and spent oxidant discharged from the cell (21) are mixed and disposed outside the discharge path (18, 19, 27) for discharge to the outside, and the discharge path (18, 19, 27). The detection means (44) for detecting the presence or absence of unreacted fuel and the detection means (44) in the discharge passage (18, 19, 27) are arranged upstream of the position where the detection means (44) is arranged, and are generated from itself. Using the heat of combustion A control method for a fuel cell system, comprising combustion means (31) for heating the fuel cell (21) and measurement means (41, 42) for measuring the temperature of the fuel cell (21). Then, based on the detection step (44) for supplying the fuel and the oxidant to the fuel cell (21) and the detection result by the detection means (44), the fuel cell system supplies the fuel. A calculation step (S130, S180, S240) for calculating a range of the ratio of the fuel and the oxidant so that the amount of the oxidant is excessive as compared with the amount of oxidant necessary for complete consumption; The amount of fuel supplied by the fuel supply means (13, 14) is adjusted so that the ratio of the fuel and oxidant supplied to the fuel battery cell (21) is within the range of the ratio calculated in the calculation step. And a control step (S110) of controlling so that no unreacted fuel exists in the discharge passages (18, 19, 27) by controlling at least one of the oxidant supply amounts by the oxidant supply means (11, 12). To S260), and as the control step (S110 to S260), the fuel and the oxidant are supplied to the combustion means (31), and the measurement means (41, 42) is used for the measurement. After the first heating step (S110 to S160) for heating until the fuel temperature reaches the first temperature for starting the fuel cell, and after the first heating step (S110 to S160), the combustion means By supplying the fuel and the oxidant to (31), the temperature measured by the measuring means (41, 42) is higher than the first temperature, and the fuel cell is A second heating step (S170 to S210) for heating until the second temperature for power generation is reached, and a power generation start step for starting power generation by the fuel cell after the second heating step (S170 to S210) (S250) is performed.

  Moreover, in the control method of the fuel cell system, in the control step (S110 to S260), the excess ratio of the amount of oxidant to the amount of oxidant necessary to completely consume the fuel is 1.1 to At least one of the fuel supply amount and the oxidant supply amount may be controlled to be within the range of 2.0.

  Further, in the control method of the fuel cell system, as the control step (S110 to S260), the temperature measured by the first measuring means (41, 42) after the power generation start step (S250) is determined in advance. If the measurement result is equal to or greater than the threshold, a ratio increasing step (S450) for increasing the ratio to such an extent that the combustion means (31) does not misfire may be performed.

  In order to achieve the above object, the following reference invention may be used. That is, the fuel cell system of the reference invention includes a fuel cell that generates electric power by chemically reacting a fuel and an oxidant via an electrolyte body, a fuel supply unit that supplies fuel to the negative electrode of the fuel cell, An oxidant supply means for supplying an oxidant to the positive electrode of the fuel cell, and a discharge path for mixing the spent fuel and spent oxidant discharged from the fuel cell and discharging them to the outside Detecting means for detecting the presence or absence of unreacted fuel in the discharge passage; and at least one of a fuel supply amount by the fuel supply means and an oxidant supply amount by the oxidant supply means based on a detection result by the detection means Is provided with supply control means for controlling so that no unreacted fuel is present in the discharge passage.

  That is, in the fuel cell system, when the fuel becomes excessive or the oxidant becomes excessive and the reaction temperature is lowered, the unreacted fuel is discharged to the outside. For this reason, in the present invention, the detection means is used to monitor the presence or absence of unreacted fuel in the discharge passage, and based on this result, the fuel supply amount is set so that the fuel supplied to the fuel cell is consumed well. In addition, at least one of the oxidant supply amount is controlled.

  Here, when unreacted fuel is detected in the discharge path, if the fuel supply amount is controlled to be reduced, the fuel can be saved, and if the control is performed to increase the oxidant supply amount, the fuel cell can be removed. The amount of power can be increased.

Therefore, according to such a fuel cell system, the fuel consumption efficiency can be improved.
By the way, in the fuel cell system described above, the detection means may be anything as long as it can detect unburned gas, but it can detect unreacted fuel by detecting the oxygen concentration in the exhaust passage. Is desirable.

  Therefore, according to such a fuel cell system, not only the unreacted fuel in the discharge passage is completely consumed, but also the fuel supply amount or the oxidant so that the oxygen concentration becomes a preset concentration. Since the supply amount can be controlled, the fuel supply amount and the oxidant supply amount can be controlled to a ratio suitable for the chemical reaction. For this reason, the fuel consumption efficiency by a fuel cell can be improved more.

  Further, in the fuel cell system described above, when the fuel cell system includes a combustion unit that is disposed upstream of the position where the detection unit is disposed in the discharge path and burns unreacted fuel in the discharge path. The exhaust path is preferably configured to exhaust the exhaust discharged from the combustion means to the outside after passing through the periphery of the fuel cell.

  According to such a fuel cell system, the gas heated by the combustion means can be supplied to the fuel cell, so that the fuel cell can be heated to a temperature suitable for the chemical reaction by the heat of the gas. For this reason, when it is necessary to warm up the fuel cell as in the case where a solid electrolyte is used as the electrolyte of the fuel cell, the fuel consumption efficiency can be improved.

In addition, since the unreacted fuel can be completely burned by the combustion means, it is possible to reliably prevent the unreacted fuel from being discharged to the outside.
Furthermore, in the fuel cell system described above, it is determined whether or not the first measurement unit that measures the temperature of the fuel cell and the measurement result by the first measurement unit is equal to or greater than a predetermined first threshold value. The first cooling control means for increasing the amount of the oxidant supplied to the fuel cell via the oxidant supply means when the measurement result is equal to or more than the first threshold is preferably provided.

  According to such a fuel cell system, when the temperature of the fuel cell rises too much, a large amount of oxidant is supplied, so that the fuel cell can be lowered to a temperature suitable for a chemical reaction for power generation. . In addition, by maintaining the fuel cell at a temperature suitable for a chemical reaction in this way, the fuel cell can consume fuel more favorably.

When the present invention is applied to this fuel cell system, the supply control means may increase the amount of oxidant within the range of the air-fuel ratio in which the combustion means can burn unreacted fuel.
In addition, in any one of the fuel cell systems described above, by supplying a liquid or gas to the second measuring means for measuring the temperature of the fuel cell and the flow path formed around the fuel cell, Whether the liquid or gas in the flow path absorbs heat from the fuel battery cell and cools the fuel battery cell, and whether the measurement result by the second measurement means is greater than or equal to a preset second threshold value It is desirable to include a second cooling control unit that determines whether or not and when the measurement result is equal to or greater than the second threshold value, supplies liquid or gas to the flow path via the cooling unit.

  According to such a fuel cell system, the fuel cell can be more reliably lowered to a temperature suitable for a chemical reaction for power generation, so that fuel can be consumed more favorably by the fuel cell.

  Moreover, the liquid and gas warmed by the fuel battery cell can be easily taken out.

It is explanatory drawing which shows the structure of a fuel cell system typically. It is a block diagram which shows the electrical connection relationship of a fuel cell system. It is a flowchart which shows a fuel cell control process. It is the flowchart (a) which shows the stop process which a control part performs, and the flowchart (b) which shows a power generation control process.

Embodiments according to the present invention will be described below with reference to the drawings.
FIG. 1 is an explanatory view schematically showing the structure of a fuel cell system 1 to which the present invention is applied.
As shown in FIG. 1, the fuel cell system 1 includes a fuel cell unit 20, a number of pipes connected to the fuel cell unit 20, and a number of devices connected to these pipes.

The fuel cell unit 20 includes a substantially cylindrical fuel cell 21 and a cover member 22 that covers the periphery of the fuel cell 21 along the shape of the fuel cell 21.
For example, the fuel cell 21 has a structure in which a number of known solid oxide fuel cells (SOFCs) are stacked, and a positive electrode terminal 46 is formed by chemically reacting fuel and an oxidant via an electrolyte inside. And negative electrode terminal 48 generate electric power. Note that the positive electrode terminal 46 and the negative electrode terminal 48 are connected to wiring (positive electrode side wiring 47 and negative electrode side wiring 49) for energization from these terminals to the object to be driven.

  Further, the negative electrode side wiring 49 is provided with a fuel cell switch 33 that can cut off the energization by the fuel cell 21. When the fuel cell switch 33 is in an energized state, a chemical reaction for generating electric power occurs in the fuel cell 21, and when the fuel cell switch 33 is in an interrupted state, the chemical reaction in the fuel cell 21 is stopped. Will be. The fuel cell switch 33 is in a cut-off state at the start of a fuel cell control process (see FIG. 3) described later.

In addition, cell temperature sensors 41 and 42 that measure the surface temperature of the fuel cell 21 are disposed in the fuel cell 21 at two locations, an upper portion and a lower portion.
The cover member 22 is not in close contact with the fuel cell 21 and is formed with a gap through which gas burned by a burner 31 (combustion means referred to in the present invention) described later can be introduced. The cover member 22 includes a water channel 23 (a channel referred to in the present invention) into which cooling water for cooling the fuel cell 21 can be injected. The water channel 23 follows the shape of the side surface of the fuel cell 21. It is formed in a spiral shape.

  Next, in the fuel cell 21 of the fuel cell unit 20, as the above-described piping, first, an air supply pipe 11 for introducing air as an oxidant into the fuel cell unit 20 and a hydrocarbon compound ( For example, methane) and a fuel supply pipe 13 for introducing water vapor are connected.

  Further, the air supply pipe 11 and the fuel supply pipe 13 include valves for adjusting the flow rate of the gas flowing through the pipes (air introduction valve 12 (along with the air supply pipe 11 and corresponding to the oxidant supply means in the present invention). ) And a fuel introduction valve 14 (corresponding to the fuel supply means in the present invention together with the fuel supply pipe 13)).

  Further, an air discharge pipe 16 that discharges the oxidant introduced from the air supply pipe 11 and a fuel discharge pipe 15 that discharges the fuel introduced from the fuel supply pipe 13 are connected to the fuel cell 21. .

  Further, air is provided downstream of the air discharge pipe 16 and the fuel discharge pipe 15 (downstream with respect to the direction in which air and fuel flow: the end opposite to the end where the fuel cells 21 are connected). A mixer 17 for mixing the gas flowing through the discharge pipe 16 and the fuel discharge pipe 15 is provided, and an air mixture pipe 18, a burner 31, and a warm air introduction pipe 19 are connected in this order further downstream from the mixer 17. Yes.

  Here, the burner 31 generates a seed fire by burning another fuel supplied from the outside, and causes the unreacted fuel supplied from the gas mixture tube 18 to ignite, thereby completely burning the unreacted fuel. . The downstream end of the warm air introduction pipe 19 is connected to the inside of the cover member 22 (position close to the upper end), and the exhaust gas heated by the burner 31 passes through the warm air introduction pipe 19 to the fuel cell. 21 and the cover member 22 are configured to be supplied to the gap.

  The cover member 22 (position close to the lower end) corresponds to an exhaust pipe 27 for discharging exhaust gas introduced from the warm air introduction pipe 19 (along with the mixed gas pipe 18 and the warm air introduction pipe 19). ) Is connected. In this exhaust pipe 27, an exhaust temperature sensor 43, an entire-range air-fuel ratio sensor 44 (detection means in the present invention), and a catalyst 32 are arranged in order from the fuel cell unit 20.

  The catalyst 32 is configured, for example, as a known three-way catalyst, and is arranged to prevent unreacted fuel from being discharged to the outside in case the burner 31 misfires. The exhaust gas that has passed through the catalyst 32 is discharged to the outside through the exhaust port 28.

Next, the water path 23 of the cover member 22 is provided with a cooling water introduction pipe 24 for introducing cooling water and a cooling water discharge pipe 26 for discharging cooling water from the water path.
The cooling water introduction pipe 24 and the cooling water discharge pipe 26 are provided with a cooling water introduction valve 25 and a cooling water discharge valve 29 for introducing or discharging the cooling water.

The water passage 23, the cooling water introduction pipe 24, the cooling water introduction valve 25, the cooling water discharge pipe 26, and the cooling water discharge valve 29 correspond to the cooling means in the present invention.
Here, the substances (air, fuel, and cooling water) on the upstream side of each valve are pressurized at a constant pressure, and the substances that pass through each valve simply by adjusting the opening of each valve. The flow rate can be adjusted.

Next, the control system of the fuel cell system 1 will be described with reference to FIG. FIG. 2 is a block diagram showing an electrical connection relationship of the fuel cell system 1.
As shown in FIG. 2, the control system of the fuel cell system 1 is configured around a control unit 51 as a known microcomputer having a CPU, a ROM, a RAM, and the like. The control unit 51 incorporates functions as a voltage measurement unit 53 and a generated power amount measurement unit 54 that monitor the output (for example, voltage and current) from the fuel cell 21.

  The control unit 51 includes various sensors (first measurement means and second measurement means in the present invention: specifically, cell temperature sensors 41 and 42, an exhaust temperature sensor 43, and a full-range air-fuel ratio sensor 44). Based on the detection result, various valves (specifically, the air introduction valve 12, the fuel introduction valve 14, the cooling water introduction valve 25, the cooling water discharge valve 29), the burner 31, the fuel cell switch 33, and the like are driven and controlled. .

  In addition, the control unit 51 is also connected to an external device and a command input unit 52 for inputting an external command based on a user's operation. The control unit 51 receives a command from the command input unit 52. In the event of a failure, various valves are driven and controlled.

  In addition, the control unit 51 (ROM) is used to warm up or cool the fuel cell, as well as the degree of opening (reference amount) of various valves used for air-fuel ratio control in the fuel cell control process described later. The allowable temperature range, the power generation allowable temperature, the first and second limit temperatures, and the like are stored. In the information about these temperatures, the power generation allowable temperature and each limit temperature are set for each temperature sensor 41 to 43.

  Further, in the control unit 51 (ROM), an allowable air-fuel ratio range indicating a target air-fuel ratio range by the full-range air-fuel ratio sensor 44 is also stored. Note that when the detection result by the full-range air-fuel ratio sensor 44 is within the allowable air-fuel ratio range, the unreacted fuel is not discharged to the outside.

Next, a process for driving the fuel cell system 1 described above will be described with reference to FIG. FIG. 3 is a flowchart showing a fuel cell control process executed by the control unit 51.
In the fuel cell control process, the processes of S150 to S160, S180 to S190, and S230 to S240 correspond to the supply control means in the present invention.

This process is started when the fuel cell system 1 is activated, and in S110 to S160, control is performed to favorably ignite and burn the burner 31.
That is, in S110, the air introduction valve 12 and the fuel introduction valve 14 are opened by the first reference amount stored in the ROM, and the process proceeds to S120.

  In S <b> 120, the burner 31 is ignited immediately before fuel and air (oxidant) reach the burner 31. Note that the ignition timing of the burner 31 is controlled by a timer built in the control unit 51, and when a preset time has elapsed after the processing of S110, the processing of S120 is executed.

  And it transfers to S130 and it is determined whether the temperature detected by each temperature sensor 41-43 is in the tolerance | permissible range memorize | stored in ROM. If all the temperatures detected by the temperature sensors 41 to 43 are within the allowable range, the process proceeds to S150, and if any of the temperatures detected by the temperature sensors 41 to 43 is outside the allowable range, the process proceeds to S140. .

  In S140, the air introduction valve 12 and the fuel introduction valve 14 are closed, the burner 31 is extinguished, and the fuel cell control process is terminated. That is, it is assumed that an abnormality has occurred in the fuel cell system 1, and this system is stopped.

  Further, in S150, it is determined whether or not the detection result by the full-range air-fuel ratio sensor 44 is within the allowable air-fuel ratio range stored in the ROM. If the detection result is within the allowable air-fuel ratio range, the process proceeds to S170, and if the detection result is not within the allowable air-fuel ratio range, the process proceeds to S160. In the present embodiment, the allowable air-fuel ratio range is set such that the excess air ratio is 1.1 to 2.0, for example.

In S160, the opening degree of the air introduction valve 12 is adjusted so that the detection result by the full-range air-fuel ratio sensor 44 falls within the allowable air-fuel ratio range, and the process returns to S130.
Next, in S170 to S220, processing for warming up is performed until the fuel cell 21 reaches a target temperature.

  That is, in S170, in order to supply more air and fuel than the first reference amount, the air introduction valve 12 and the fuel introduction valve 14 are opened by the second reference amount stored in the ROM.

Then, the flow shifts to S180, where it is determined whether or not the detection result by the entire region air-fuel ratio sensor 44 is within the allowable air-fuel ratio range stored in the ROM. If the detection result is within the allowable air-fuel ratio range, the process proceeds to S200, and if the detection result is not within the allowable air-fuel ratio range, the process proceeds to S190.

In S190, the opening degree of the air introduction valve 12 is adjusted so that the detection result by the full-range air-fuel ratio sensor 44 falls within the allowable air-fuel ratio range, and the process returns to S180.
In S200, it is determined whether or not the temperatures detected by the temperature sensors 41 to 43 are equal to or higher than the power generation allowable temperature stored in the ROM. If all the temperatures detected by the temperature sensors 41 to 43 are equal to or higher than the power generation allowable temperature, the process proceeds to S210. If any of the temperatures detected by the temperature sensors 41 to 43 is lower than the power generation allowable temperature, the process proceeds to S180. Return.

  In S210, the output voltage from the fuel cell 21 is monitored via the voltage measuring unit 53, and it is determined whether or not the output voltage is normal. If the output voltage is normal, the process proceeds to S220, and if the output voltage is not normal, the process returns to S180.

Next, in S220 to S250, processing for further increasing the fuel supply amount is performed in preparation for power generation performed by the fuel cell 21.
That is, in S220, the air introduction valve 12 and the fuel introduction valve 14 are opened by the third reference amount stored in the ROM, and the process proceeds to S230.

  In S230, it is determined whether or not the detection result by the full-range air-fuel ratio sensor 44 is within the allowable air-fuel ratio range stored in the ROM. If the detection result is within the allowable air-fuel ratio range, the process proceeds to S250, and if the detection result is not within the allowable air-fuel ratio range, the process proceeds to S240.

In S240, the opening degree of the air introduction valve 12 is adjusted so that the detection result by the full-range air-fuel ratio sensor 44 falls within the allowable air-fuel ratio range, and the process returns to S230.
In S250, the fuel cell switch 33 is switched from the cut-off state to the energized state, and the process proceeds to S260.

  In S260, the power generation control process is repeatedly executed. This power generation control process is a process for continuously performing the power generation performed by the fuel battery cell 21, and details of this process will be described later.

  The power generation control process is interrupted when a stop command is input via the command input unit 52 during the process execution, and the stop process shown in FIG. 4A is executed instead. FIG. 4A is a flowchart showing a stop process executed by the control unit 51.

In the stop process shown in FIG. 4A, first, in S310, if the fuel cell switch is in an energized state, it is switched to a cut-off state.
Then, the process proceeds to S320, and the air introduction valve 12 and the fuel introduction valve 14 are gradually closed (in a stepwise manner based on the control amount stored in the ROM).

  Next, the process proceeds to S330, and it is determined whether or not the air introduction valve 12 and the fuel introduction valve 14 are completely closed. If each valve is completely closed, the process proceeds to S340, and if any valve is open, the process returns to S320.

In S340, the burner 31 is extinguished and the stop process is terminated.
Here, the power generation control process (S260) in the fuel cell control process (FIG. 3) will be described with reference to FIG. 4B. FIG. 4B is a flowchart showing the power generation control process.

  During this power generation control process, the control unit 51 calculates the amount of fuel required in the fuel cell 21 by the generated power amount measurement unit 54, and always supplies the fuel supply amount so as to match this calculation result. The opening degree of the fuel introduction valve 14 is adjusted.

  In this power generation control process, the processes of S410 and S450 correspond to the first cooling control means in the present invention, and the processes of S470 to S480 and S500 to S510 correspond to the second cooling control means.

  In the power generation control process shown in FIG. 4B, first, in S410, it is determined whether or not the temperatures detected by the temperature sensors 41 to 43 are equal to or higher than the first limit temperature stored in the ROM. If any of the temperatures detected by the temperature sensors 41 to 43 is equal to or higher than the first limit temperature, the process proceeds to S450, and if all of the temperatures detected by the temperature sensors 41 to 43 are less than the first limit temperature, Return to S420.

  In S420, it is determined whether or not the detection result by the full-range air-fuel ratio sensor 44 is within the allowable air-fuel ratio range stored in the ROM. If the detection result is within the allowable air-fuel ratio range, the process proceeds to S440. If the detection result is not within the allowable air-fuel ratio range, the process proceeds to S430.

In S430, the opening degree of the air introduction valve 12 is adjusted so that the detection result by the full-range air-fuel ratio sensor 44 falls within the allowable air-fuel ratio range, and the process proceeds to S440.
In S440, it is determined whether or not the valve flag recorded in the RAM is ON. If the valve flag is ON, the process proceeds to S480, and if the valve flag is OFF, the power generation control process is terminated. Here, the valve flag is a flag indicating whether or not the cooling water introduction valve 25 and the cooling water discharge valve 29 are opened, and when the valve flag is ON, the cooling water introduction valve 25 and the cooling water The water discharge valve 29 is opened.

Next, in S450, the air-fuel ratio is raised to such an extent that the burner 31 does not misfire (the lowest air-fuel ratio previously stored in the ROM). That is, the air introduction valve 12 is opened so that this air-fuel ratio is obtained.
Then, the process proceeds to S460, and it is determined whether or not the valve flag is ON. If the valve flag is ON, the process proceeds to S470, and if the valve flag is OFF, the process proceeds to S500.

  In S470 and S500, it is determined whether or not the temperature detected by each of the temperature sensors 41 to 43 is equal to or higher than the second limit temperature stored in the ROM. In S470, if any of the temperatures detected by the temperature sensors 41 to 43 is equal to or higher than the second limit temperature, the power generation control process is repeated from the beginning, and all of the temperatures detected by the temperature sensors 41 to 43 are second. If it is less than the limit temperature, the process proceeds to S480. In S500, if any of the temperatures detected by the temperature sensors 41 to 43 is equal to or higher than the second limit temperature, the process proceeds to S510, and all the temperatures detected by the temperature sensors 41 to 43 are the second limit temperature. If it is less than the temperature, the power generation control process is repeated from the beginning.

In S480, the cooling water introduction valve 25 and the cooling water discharge valve 29 are closed, and the process proceeds to S490.
In S490, the valve flag in the RAM is set to OFF, and the power generation control process is repeated from the beginning.

In S510, the cooling water introduction valve 25 and the cooling water discharge valve 29 are opened, and the process proceeds to S520.
In S520, the valve flag in the RAM is set to ON, and the power generation control process is repeated from the beginning.

  In the fuel cell system 1 described in detail above, the fuel is supplied to the fuel cell 21 that generates electric power by chemically reacting the fuel and the oxidant via the solid electrolyte body, and the negative electrode of the fuel cell 21. The fuel supply pipe 13 and the fuel introduction valve 14, the air supply pipe 11 and the air introduction valve 12 for supplying the oxidant to the positive electrode of the fuel cell 21, the spent fuel discharged from the fuel cell 21 and the used oxidation. An all-range air-fuel ratio sensor 44 that is disposed in an exhaust pipe 27 for mixing and discharging the agent and detects unreacted fuel by detecting the oxygen concentration in the exhaust pipe 27; It is equipped with.

  Then, in the fuel cell system 1, the control unit 51 controls the opening degree of the air introduction valve 12 based on the detection result by the entire region air-fuel ratio sensor 44, thereby reducing the oxidant supply amount into the exhaust pipe 27. Control so that no reactive fuel is present.

  Therefore, according to such a fuel cell system 1, when unreacted fuel is detected in the exhaust pipe 27, the amount of power from the fuel cell 21 can be increased by increasing the oxidant supply amount. , Fuel consumption efficiency can be improved.

  Further, not only the unreacted fuel in the exhaust pipe 27 is completely consumed, but also the fuel supply amount or the oxidant supply amount is controlled so that the oxygen concentration becomes a preset concentration. The supply amount and the oxidant supply amount can be controlled to a ratio suitable for the chemical reaction.

  Further, in the fuel cell system 1 of the present embodiment, the burner is disposed upstream of the position where the full-range air-fuel ratio sensor 44 is disposed in the exhaust pipe 27 and burns unreacted fuel in the exhaust pipe 27. 31 is provided. The exhaust pipe 27 is configured to exhaust the exhaust discharged from the burner 31 to the outside after passing through the periphery of the fuel cell 21.

  Therefore, according to such a fuel cell system 1, the gas heated by the burner 31 can be supplied to the fuel cell 21, so that the fuel cell 21 is brought to a temperature suitable for a chemical reaction by the heat of this gas. Can be warmed. For this reason, the electrolyte body (solid electrolyte body) of the fuel battery cell 21 can be warmed up efficiently.

In addition, since the unreacted fuel can be completely burned by the burner 31, it is possible to reliably prevent the unreacted fuel from being discharged to the outside.
Furthermore, when the fuel is consumed in the fuel cell 21, the amount of fuel supplied to the burner 31 is reduced, so that the fuel cell 21 can be prevented from being excessively warmed. For this reason, the temperature management of the fuel cell 21 can be easily performed.

  Further, the fuel cell system 1 of the present embodiment includes temperature sensors 41 to 43 that measure the temperature of the fuel cell 21, and the control unit 51 determines the measurement results of the temperature sensors 41 to 43 in advance. The oxidant is supplied to the fuel cell 21 via the air supply pipe 11 and the air introduction valve 12 when it is determined whether or not the measured temperature is equal to or higher than the first limit temperature. Configured to increase the amount of. At this time, the control unit 51 increases the amount of the oxidant within the range of the air-fuel ratio in which the burner 31 can burn the unreacted fuel.

  Therefore, according to such a fuel cell system 1, when the temperature of the fuel cell 21 rises too much, a large amount of oxidant is supplied, so that the temperature of the fuel cell 21 is suitable for a chemical reaction for power generation. Can be lowered. In addition, by maintaining the fuel cell 21 at a temperature suitable for a chemical reaction in this way, fuel can be consumed more favorably by the fuel cell 21, so that unreacted fuel is discharged to the outside. Can be prevented. Moreover, it is possible to prevent the burner 31 from being misfired.

  In addition, in the fuel cell system 1 of the present embodiment, by supplying cooling water to the water channel 23 formed around the fuel cell 21, the liquid or gas in the water channel 23 is supplied to the liquid or gas from the fuel cell 21. A cooling water introduction pipe 24, a cooling water introduction valve 25, a cooling water discharge pipe 26, and a cooling water discharge valve 29 for absorbing heat and cooling the fuel battery cell 21 are provided.

  And the control part 51 determines whether the measurement result by each temperature sensor 41-43 is more than the preset 2nd limit temperature, and when a measurement result is more than the 2nd limit temperature, it is cooling water. The introduction pipe 24, the cooling water introduction valve 25 and the cooling water discharge valve 29 are opened to supply cooling water to the water channel 23.

  According to such a fuel cell system 1, the fuel cell 21 can be more reliably lowered to a temperature suitable for a chemical reaction for power generation, and unreacted fuel is prevented from being discharged to the outside. Can do.

Further, the cooling water warmed by the fuel cell 21 can be easily taken out.
The embodiment of the present invention is not limited to the above-described embodiment, and can take various forms as long as it belongs to the technical scope of the present invention.

  For example, in the present embodiment, the control unit 51 is configured to control the opening degree of the air introduction valve 12 based on the detection result by the entire region air-fuel ratio sensor 44, but the opening degree of the fuel introduction valve 14 is controlled. You may comprise. Moreover, you may comprise so that the opening degree of both the air introduction valve 12 and the fuel introduction valve 14 may be controlled.

Even if it does in this way, fuel can be saved and the consumption efficiency of fuel can be improved more.
In the present embodiment, the full-range air-fuel ratio sensor 44 is used to detect unburned gas in the exhaust pipe 27. However, for example, an HC sensor or the like that can detect unburned gas is used. Anything can be used.

  Furthermore, in the present embodiment, the cooling water is injected when the temperature of the fuel cell 21 becomes equal to or higher than the second limit temperature. However, any other material that can absorb heat from the fuel cell 21 is used. A liquid or gas may be injected.

  Moreover, although the burner 31 of the present embodiment is configured to maintain the seed fire by supplying the fuel with a separate system, it may be configured to simply fly a spark for igniting unreacted fuel. Even if it does in this way, the effect similar to the fuel cell system 1 of a present Example can be acquired.

  DESCRIPTION OF SYMBOLS 1 ... Fuel cell system, 11 ... Air supply pipe, 12 ... Air introduction valve, 13 ... Fuel supply pipe, 14 ... Fuel introduction valve, 15 ... Fuel discharge pipe, 16 ... Air discharge pipe, 17 ... Mixer, 18 ... Mixing 19: Warm air introduction pipe, 20 ... Fuel cell unit, 21 ... Fuel cell, 22 ... Cover member, 23 ... Water channel, 24 ... Cooling water introduction pipe, 25 ... Cooling water introduction valve, 26 ... Cooling water discharge pipe, 27 ... exhaust pipe, 28 ... exhaust port, 29 ... cooling water discharge valve, 31 ... burner, 32 ... catalyst, 33 ... fuel cell switch, 41 ... cell temperature sensor, 42 ... cell temperature sensor, 43 ... exhaust temperature sensor, 44 ... all-range air-fuel ratio sensor, 46 ... positive electrode terminal, 47 ... positive electrode side wiring, 48 ... negative electrode terminal, 49 ... negative electrode side wiring, 51 ... control unit, 52 ... command input unit, 53 ... voltage measurement unit, 54 ... generated power Quantity measuring part.

Claims (3)

A fuel battery cell (21) for generating electric power by chemically reacting a fuel and an oxidant via an electrolyte body;
Fuel supply means (13, 14) for supplying fuel to the negative electrode of the fuel cell (21);
Oxidant supply means (11, 12) for supplying an oxidant to the positive electrode of the fuel cell (21);
The spent fuel and spent oxidant discharged from the fuel battery cell (21) are mixed and disposed inside a discharge path (18, 19, 27) for discharge to the outside. The discharge path (18, 19 , 27) detecting means (44) for detecting the presence or absence of unreacted fuel;
It is arranged on the upstream side of the position where the detection means (44) is arranged in the discharge passage (18, 19, 27), and warms the fuel cell (21) using the combustion heat generated from itself. Combustion means (31) for
Measuring means (41, 42) for measuring the temperature of the fuel cell (21);
A control method for a fuel cell system comprising:
A supply step (S110, S170, S220) of supplying the fuel and the oxidant to the fuel cell (21);
Based on the detection result by the detection means (44), the fuel and the oxidant are used so that the amount of the oxidant is larger than the amount of the oxidant necessary for completely consuming the fuel in the fuel cell system. A calculation step (S130, S180, S240) for calculating a range of the ratio of
The amount of fuel supplied by the fuel supply means (13, 14) and the oxidation so that the ratio of the fuel and oxidant supplied to the fuel battery cell (21) is within the range of the ratio calculated in the calculation step. A control step (S110 to S260) for controlling so that no unreacted fuel exists in the discharge passages (18, 19, 27) by controlling both the oxidant supply amount by the agent supply means (11, 12). ,
With
As the control step (S110 to S260),
The temperature measured by the measuring means (41, 42) by supplying the fuel and the oxidant to the combustion means (31) becomes the first temperature for starting the fuel cell. A first heating step (S110 to S160) for heating up to
By supplying the fuel and the oxidant to the combustion means (31) after the first heating step (S110 to S160), the temperature measured by the measurement means (41, 42) is A second heating step (S170 to S210) in which heating is performed until the fuel cell reaches a second temperature for generating electricity, which is higher than the first temperature;
After the second heating step (S170 to S210), a power generation start step (S250) for starting power generation by the fuel cell,
The control method of the fuel cell system characterized by implementing. In the control method of the fuel cell system according to claim 1,
In the control step (S110 to S260), the fuel supply amount and the excess ratio of the amount of oxidant to the amount of oxidant necessary to completely consume the fuel are within the range of 1.1 to 2.0. A method for controlling a fuel cell system, comprising controlling at least one of an oxidant supply amount. In the control method of the fuel cell system according to claim 1 or 2,
As the control step (S110 to S260),
After the power generation start step (S250), it is determined whether or not the temperature measured by the first measuring means (41, 42) is equal to or higher than a predetermined threshold, and the measurement result is equal to or higher than the threshold. The ratio increasing step (S450) for increasing the ratio to such an extent that the combustion means (31) does not misfire.
The control method of the fuel cell system characterized by implementing.

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