JP2010182518A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system for improving temperature detection of a fuel cell without hampering warming up of the fuel cell. <P>SOLUTION: The fuel cell system includes: a first refrigerant circuit 41A cooling refrigerant discharged from the fuel cell 10 with a radiator 42 to be returned to the fuel cell 10; and a second refrigerant circuit 41B with a refrigerant amount set smaller than the refrigerant amount of the first refrigerant circuit 41A. To start up the fuel cell 10 at low temperatures, a second refrigerant pump 45 is started with the drive of a first refrigerant pump 44 stopped, so as to circulate the refrigerant between the fuel cell 10 and the second refrigerant circuit 41B. This allows a temperature sensor 52 to accurately detect the temperature of the fuel cell 10, preventing the fuel cell 10 from being excessively cooled. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fuel cell system that cools a fuel cell by circulating a refrigerant.

  In order to prevent overheating of the fuel cell during power generation, the fuel cell system includes a cooling system that circulates a refrigerant in the fuel cell to cool the fuel cell. However, when the fuel cell system is activated in a low temperature (for example, below freezing point) environment, the fuel cell is warmed up. However, if the refrigerant is circulated at the time of starting the system in a low temperature environment, the fuel cell is cooled and the warm-up is hindered. Therefore, a technique for promoting the warm-up by blocking the flow of the refrigerant has been proposed. . However, since the temperature of the fuel cell is often detected with a refrigerant, the temperature of the fuel cell cannot be detected if the flow of the refrigerant is interrupted. Therefore, a technique for intermittently operating a refrigerant pump for circulating the refrigerant has been proposed in order to detect the temperature of the fuel cell (see, for example, Patent Document 1).

Japanese translation of PCT publication No. 2005-518077 (paragraph 0011, FIG. 1)

  However, if the refrigerant supplied to the fuel cell is circulated intermittently as described in Patent Document 1, the temperature of the fuel cell and the temperature of the refrigerant deviate, and the temperature of the fuel cell is accurately grasped. There was a problem that became difficult.

  The present invention solves the above-described conventional problems, and an object thereof is to provide a fuel cell system capable of improving the temperature detection performance of the fuel cell without inhibiting warm-up.

  The present invention provides a fuel cell that is supplied with a reaction gas to generate power, a reaction gas device through which the reaction gas flows, and a refrigerant discharged from the fuel cell by a heat exchanger and returned to the fuel cell. A refrigerant circulation path; a first circulation means for circulating the refrigerant in the first refrigerant circulation path; and a temperature detection means for detecting a temperature of the refrigerant discharged from the fuel cell, the detection of the temperature detection means A fuel cell system that controls the fuel cell based on a value, a flow rate limiting means for limiting a flow rate of the refrigerant flowing through the first refrigerant circulation path, and a first circulation means of the first refrigerant circulation path. A second refrigerant circulation path that branches from the upstream side and merges with the downstream side of the first circulation means and has a smaller amount of refrigerant than the first refrigerant circulation path, and a refrigerant in the second refrigerant circulation path A second circulation means for circulating A heat exchanging part arranged in the second refrigerant circulation path and exchanging heat with the reaction gas device, and when the flow rate of the refrigerant flowing through the first refrigerant circulation path is limited by the flow rate limiting means, A refrigerant is circulated through the second refrigerant circulation path.

  According to this, since the refrigerant can be circulated in the second refrigerant circulation path by the second circulation means, the temperature detection means detects the temperature of the fuel cell even when the circulation of the refrigerant in the first refrigerant circulation path is restricted. Can be done accurately. Therefore, the fuel cell can be accurately controlled.

  Moreover, since the amount of refrigerant flowing through the second refrigerant circuit is set to be smaller than the amount of refrigerant flowing through the first refrigerant circuit, the fuel cell is not cooled by the refrigerant flowing at the normal power generation rate. Therefore, it becomes possible to prevent the fuel cell from being excessively cooled.

  Furthermore, since the refrigerant that has been heated and discharged by the heat generated during power generation of the fuel cell is circulated through the heat exchanging unit to exchange heat with the reaction gas device, the temperature of the reaction gas device is increased ( It is possible to defrost)

  The reactive gas device is, for example, a gas-liquid separator that separates generated water discharged from the anode side of the fuel cell and the reactive gas, and a back pressure control valve that controls the pressure on the cathode side of the fuel cell.

  In addition, when the refrigerant circulation stop propriety determining means for determining whether or not to stop the refrigerant circulation in the second refrigerant circulation path is determined and the refrigerant circulation stop propriety determining means determines that the refrigerant circulation is stopped, Is characterized in that the circulation of the refrigerant in the second refrigerant circuit is stopped and the refrigerant is circulated only in the first refrigerant circuit.

  According to this, since the refrigerant does not flow through the second refrigerant circuit, the amount of heat received by the refrigerant from the reaction gas device is eliminated, and the cooling performance when cooling the fuel cell can be improved. In addition, since the refrigerant is not circulated unnecessarily in the second refrigerant circulation path, the power consumed by the second circulation means can be reduced. Note that the refrigerant circulation stop propriety determination unit can determine, for example, based on whether or not the fuel cell has been warmed up, in other words, whether or not the temperature of the fuel cell has reached the warm-up complete temperature.

  In addition, it has a low temperature start determination means for determining whether or not to start the fuel cell at a low temperature, and when the low temperature start determination means determines that the fuel cell is to be started at a low temperature, the flow rate restriction means causes the first refrigerant circulation path to And restricts the flow rate of the refrigerant in the first refrigerant circuit when the low temperature activation determination means determines that the low temperature activation is not performed. It is characterized by not.

  According to this, since the flow rate of the refrigerant in the first refrigerant circuit is restricted when starting at a low temperature, the low temperature startability of the fuel cell can be improved, and when starting at a low temperature, that is, starting at a relatively high temperature ( When starting up at room temperature), the flow rate of refrigerant is not limited and a sufficient amount of coolant is supplied to the fuel cell for cooling, preventing the fuel cell from overheating and suppressing deterioration of the fuel cell. It becomes possible.

  ADVANTAGE OF THE INVENTION According to this invention, the fuel cell system which can improve the temperature detection performance of a fuel cell, without inhibiting warming-up can be provided.

It is a whole lineblock diagram showing the fuel cell system of a 1st embodiment. It is a flowchart which shows the refrigerant | coolant circulation control in the fuel cell system of 1st Embodiment. It is a flowchart which shows the modification of the refrigerant | coolant circulation control in the fuel cell system of 1st Embodiment. It is a map which shows the relationship between the temperature of a fuel cell, and the rotational speed of a 1st circulation pump. It is a whole block diagram which shows the fuel cell system of 2nd Embodiment. It is a map which shows the relationship between the temperature of a fuel cell, and the opening degree of a flow control valve.

  Embodiments of the present invention will be described below with reference to the drawings. In the following, the case where the fuel cell systems 1A and 1B of the present embodiment are applied to a fuel cell vehicle (not shown) will be described as an example. However, the present invention is not limited to this, and ships, aircrafts, Or it can apply to various things which require electricity, such as a stationary type for home use and business use.

(First embodiment)
As shown in FIG. 1, the fuel cell system 1A of the first embodiment includes a fuel cell 10, an anode system 20, a cathode system 30, a refrigerant system 40, a control system 50, and the like.

  The fuel cell 10 is, for example, a PEM (Proton Exchange Membrane) type fuel cell, and a single cell configured by sandwiching a MEA (Membrane Electrode Assembly) between a pair of conductive separators (not shown) in the thickness direction. A plurality of layers are stacked and electrically connected in series. The MEA is a membrane electrode assembly in which an electrolyte membrane made of a solid polymer is sandwiched between an anode (hydrogen electrode) containing a catalyst and a cathode (oxygen electrode). In addition, an anode channel 10a through which hydrogen (fuel gas) as a reaction gas flows is formed in the separator facing the anode, and air containing oxygen as the reaction gas (oxidant gas) is formed in the separator facing the cathode. ) Is circulated in the cathode channel 10b. The separator is formed with a refrigerant flow path 10c through which the refrigerant flows.

  In such a fuel cell 10, hydrogen is supplied to the anode and air (oxygen) is supplied to the cathode, and power generation is possible by a chemical reaction between hydrogen and oxygen, and water is generated at the cathode. The generated electric power (generated current) taken out from the fuel cell 10 is external to a traveling motor (not shown), an air pump 31, a first refrigerant pump 44, a second refrigerant pump 45, a power storage device (not shown), etc. Supplied to the load.

  The anode system 20 supplies hydrogen (fuel gas) to the anode of the fuel cell 10 and discharges anode off-gas (such as hydrogen) from the anode, and includes a hydrogen tank 21, a shut-off valve 22, an ejector 23, a gas-liquid It comprises a separator (reactive gas device) 24, a drain valve 25, a purge valve 26, pipes a1 to a7, and the like.

  In the anode system 20, a hydrogen tank 21 is connected to the inlet of the anode flow path 10 a of the fuel cell 10 through a pipe a 1, a shutoff valve 22, a pipe a 2, an ejector 23, and a pipe a 3. The outlet of the anode flow path 10a of the fuel cell 10 is connected to the ejector 23 through a pipe a4, a gas-liquid separator 24, and a pipe a5, and communicates with the outside of the vehicle through a pipe a6 and a drain valve 25. And a purge valve 26 communicates with the outside of the vehicle.

  The shut-off valve 22 is, for example, an electromagnetically operated type, and is opened and closed by an ECU 51 described later.

  The ejector 23 generates a negative pressure using the flow of hydrogen supplied from the hydrogen tank 21, sucks and mixes the anode off-gas by this negative pressure, and supplies it to the anode again.

  The gas-liquid separator 24 has a storage part that separates hydrogen and water by gravity and stores water. More specifically, when the produced water flowing together with the anode off-gas is introduced into the gas-liquid separator 24 from the pipe a4, the flow-path sectional area is enlarged and the flow velocity is lowered, whereby the anode off-gas and the produced water are separated. Thus, the generated water accumulates in the reservoir.

  The drain valve 25 is, for example, an electromagnetically operated type, and is periodically opened by an ECU 51 described later, and discharges water stored in the gas-liquid separator 24 to the outside of the vehicle (outside the system).

  The purge valve 26 is, for example, an electromagnetically operated type, and is periodically opened by an ECU 51 described later to remove impurities such as nitrogen contained in the hydrogen circulation path (the pipes a3 to a5 and the anode flow path 10a) outside the vehicle. To discharge. Impurities such as nitrogen are transmitted from the cathode through the electrolyte membrane to the anode.

  The cathode system 30 supplies air (oxidizing gas) to the cathode of the fuel cell 10 and discharges cathode off-gas (wet air or the like) from the cathode, and includes an air pump 31, a back pressure control valve (reactive gas device). ) 32, pipes b1 to b3, and the like.

  Further, in the cathode system 30, an air pump 31 is connected to the inlet of the cathode flow path 10b of the fuel cell 10 via the pipe b1. Further, the outlet of the cathode flow path 10b of the fuel cell 10 communicates with the outside of the vehicle via the pipe b2, the back pressure control valve 32, and the pipe b3.

  The air pump 31 is a mechanical supercharger driven by, for example, a motor, compresses outside air (air) taken in under the control of the ECU 51, and supplies the compressed air to the cathode. The pipe b1 is provided with a humidifier (not shown) that humidifies the air from the air pump 31.

  The back pressure control valve 32 is a valve capable of adjusting the opening, such as a butterfly valve, and appropriately adjusts the pressure supplied to the cathode.

  The refrigerant system 40 includes a first refrigerant circuit 41A and a second refrigerant circuit 41B.

  The first refrigerant circulation path 41A cools the fuel cell 10 by circulating the refrigerant between the fuel cell 10 and the radiator (heat exchanger) 42, and includes pipes c1 to c5. The first refrigerant circulation path 41A is provided with a thermostat 43 and a first refrigerant pump (first circulation means) 44. In addition, what has ethylene glycol as a main component is used for a refrigerant | coolant, for example.

  The radiator 42 is composed of pipes, fins, etc. formed of a metal material having a high heat dissipation property, and dissipates the refrigerant warmed by heat generated during power generation of the fuel cell 10, and the fuel is supplied via the pipe c1. It is connected to the outlet 10c2 of the refrigerant flow path 10c of the battery 10, and is connected to the inlet 10c1 of the refrigerant flow path 10c via pipes c2, c4, and c5.

  The thermostat 43 is connected to the refrigerant outlet of the radiator 42 via the pipe c2, is connected to the pipe c3 bypassing the radiator 42 via the pipe c3, and is connected to the first refrigerant pump 44 via the pipe c4. The thermostat 43 switches the refrigerant flow path to the radiator 42 side or the side bypassing the radiator 42 according to the temperature of the refrigerant. This switching may be performed, for example, by changing the volume of the wax depending on the temperature. For example, the switching may be performed electrically by a signal from the ECU 51.

  The first refrigerant pump 44 circulates refrigerant using a motor as a power source, and is connected to the inlet 10c1 of the refrigerant flow path 10c via a pipe c5. The first refrigerant pump 44 adjusts the flow rate of the refrigerant flowing through the first refrigerant circulation path 41 </ b> A when the rotational speed of the motor is controlled by the ECU 51. For example, by limiting (decreasing) the rotational speed of the motor, the flow rate of the refrigerant flowing through the first refrigerant circulation path 41A is limited or set to 0 than during normal power generation.

  When the first refrigerant pump 44 is driven by the ECU 51, the refrigerant discharged from the outlet 10c2 of the refrigerant flow path 10c passes through the pipe c1, the radiator 42, the pipe c2, the pipe c4, the pipe c5, and / or the pipe. It circulates so as to return to the inlet 10c1 of the refrigerant flow path 10c through c1, the pipe c3, the pipe c4, and the pipe c5.

  The second refrigerant circulation path 41B is a flow path used at low temperature startup, and includes pipes c10 to c14. The second refrigerant circulation path 41B is formed by branching from the pipe c1 connected to the outlet 10c2 of the refrigerant flow path 10c, and is connected to the heat exchange unit 24a and the back pressure control valve 32 provided in the gas-liquid separator 24. It is configured to join the pipe c5 connected to the inlet 10c1 of the refrigerant channel 10c through the provided heat exchange part 32a.

  In addition, the refrigerant amount held by the second refrigerant circulation path 41B (pipes c10 to c14) is, for example, smaller in pipe diameter than the pipes c1 to c5 and / or the pipe length is the first refrigerant circulation path 41A (pipe c1). ~ C5), and is configured to be shorter than the refrigerant amount held by the pipes c1 to c5. That is, the refrigerant amount held by the pipes c10 to c14 is an amount of refrigerant that does not hinder (rapidly) the temperature rise (warming up) of the fuel cell 10 when the fuel cell 10 is started up when the refrigerant is circulated. Set to

  Note that the upstream branching portion P1 and the downstream joining portion P2 of the second refrigerant circulation path 41B are arranged in the vicinity of the outlet 10c2 and the inlet 10c1 of the refrigerant flow path 10c, so that the refrigerant in the second refrigerant circulation path 41B. This is effective in reducing the amount.

  The second refrigerant circulation path 41B is provided with a second refrigerant pump (second circulation means) 45, a check valve 46, and heat exchange units 24a and 32a.

  The second refrigerant pump 45 circulates the refrigerant using a motor as a power source, and is connected to the pipe c1 via the pipe c10 and is connected to the inlet of the heat exchange unit 32a via the pipe c11. The outlet of the heat exchanging part 32a is connected to the inlet of the heat exchanging part 24a via the pipe c12, and the outlet of the heat exchanging part 24a is connected to the check valve 46 via the pipe c13. The check valve 46 is connected to the pipe c5 via the pipe c14.

  When the second refrigerant pump 45 is driven by the ECU 51, the refrigerant discharged from the outlet 10c2 of the refrigerant flow path 10c is changed into the pipe c1, the pipe c10, the pipe c11, the heat exchange unit 32a, the pipe c12, the heat exchange unit 24a, It circulates so as to return to the inlet 10c1 of the refrigerant flow path 10c through the pipe c13, the pipe c14, and the pipe c5.

  The check valve 46 is a valve that allows only the flow of the refrigerant from the pipe c13 to the pipe c14, and prevents the refrigerant from flowing back through the second refrigerant circulation path 41B when the first refrigerant pump 44 is driven. It has become.

  The heat exchanging unit 24a exchanges heat between the gas-liquid separator 24 and the refrigerant when the refrigerant flows, that is, heats the gas-liquid separator 24 with the heat of the refrigerant. The separator 24 is covered with a flow path called a so-called water jacket.

  Similarly, the heat exchanging unit 32a also exchanges heat between the back pressure control valve 32 and the refrigerant, that is, heats the back pressure control valve 32 with the heat of the refrigerant. Is covered with a flow path called a so-called water jacket.

  The control system 50 includes an ECU (Electronic Control Unit) 51, a temperature sensor (temperature detection means) 52, and the like. The temperature sensor 52 detects the temperature of the fuel cell 10 (hereinafter abbreviated as FC temperature), and is provided in the pipe c1 near the outlet 10c2 of the refrigerant flow path 10c.

  The ECU 51 includes a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory) storing a program, and the like.

  The flow rate limiting means is a means for limiting the flow rate of the refrigerant flowing through the first refrigerant circulation path 41 </ b> A, and limits the rotational speed of the motor of the first refrigerant pump 44, so that the first refrigerant circulation path 41 </ b> A and the fuel cell 10 The refrigerant does not circulate between them. In the fuel cell system 1A shown in FIG. 1, the flow restriction means is configured by the control of the ECU 51, and in the fuel cell system 1B described later shown in FIG. 5, the flow restriction valve 47 and the ECU 51 constitute the flow restriction means. .

  The refrigerant circulation stop possibility determination means is a means for determining whether or not to stop the circulation control of the refrigerant in the second refrigerant circulation path 41B. For example, has the warm-up process performed at the start of the fuel cell system 1A been completed? It can be judged by whether or not. Note that the warm-up process may be, for example, to increase the self-heating value in the fuel cell 10 by supplying air at a flow rate higher than the normal flow rate when starting at room temperature, or at a pressure higher than the normal pressure. It is also possible to supply air at a flow rate and pressure when starting at room temperature. The completion of the warm-up can be determined based on the FC temperature, and it can be determined that the warm-up is completed when the FC temperature becomes equal to or higher than a predetermined temperature.

  The low temperature activation determination means is a means for determining whether or not to start the fuel cell 10 at a low temperature, and can be determined based on, for example, the FC temperature. When the FC temperature is equal to or lower than a predetermined temperature (for example, below freezing point), it is determined that the fuel cell 10 is started at a low temperature. The determination is not limited to the FC temperature. For example, the determination may be made based on the outlet temperature on the anode side, the outlet temperature on the cathode side, the outside air temperature, and the like.

  Next, the operation of the fuel cell system 1A of the first embodiment will be described with reference to FIG. When the ignition switch of the vehicle is turned on (IG-ON) by the driver, the ECU 51 determines in step S10 whether to start the fuel cell 10 at a low temperature, that is, whether to warm up the fuel cell 10. Judgment (low temperature activation determination means). If it is determined in step S10 that the engine 51 is to be started at a low temperature (Yes), the ECU 51 proceeds to step S20, sets a flag “1”, and if it is determined that a low temperature start is not performed, that is, a normal start (a room temperature start) ( No), the process proceeds to step S30, and the flag “0” is set. The set flag is stored in the RAM.

  And it progresses to step S40 and ECU51 starts the electric power generation of the fuel cell (FC: Fuel Cell) 10. That is, the ECU 51 starts power generation by opening the shut-off valve 22 to supply hydrogen from the hydrogen tank 21 to the anode, driving the air pump 31 and supplying air to the cathode.

  In step S50, the ECU 51 refers to the flag stored in the RAM to determine whether the flag is “1”. If the flag is “1” (Yes), step S60A is performed. If the flag is “0” (No), the process proceeds to step S130.

  When the flag is “1”, in step S60A, the ECU 51 starts circulation restriction control for restricting circulation of the refrigerant in the first refrigerant circulation path 41A. That is, the ECU 51 performs control so that the first refrigerant pump 44 stops and the refrigerant does not circulate between the first refrigerant circulation path 41 </ b> A (the radiator 42) and the fuel cell 10. Accordingly, the refrigerant that has been excessively cooled by passing through the first refrigerant circulation path 41A (the radiator 42) does not circulate in the fuel cell 10.

  And it progresses to step S70 and ECU51 starts the circulation control which circulates a refrigerant | coolant to the 2nd refrigerant circulation path 41B. That is, the ECU 51 controls the refrigerant to circulate between the second refrigerant circuit 41 </ b> B and the fuel cell 10 by driving the second refrigerant pump 45. In the present embodiment, the amount of refrigerant flowing through the second refrigerant circuit 41B is set to be smaller than the amount of refrigerant flowing through the first refrigerant circuit 41A, so that the refrigerant that has passed through the second refrigerant circuit 41B is contained in the fuel cell 10. Even if it is introduced into the fuel cell 10, the fuel cell 10 is not excessively cooled.

  In addition, the refrigerant warmed by the heat generated during the power generation of the fuel cell 10 is introduced into the heat exchanging parts 32a and 24a, so that the refrigerant and the back-pressure control valve 32 and the refrigerant and the gas-liquid separator 24 are exchanged. In the meantime, heat exchange is performed, and the back pressure control valve 32 and the gas-liquid separator 24 are warmed by the heat held by the refrigerant.

  In step S80, the ECU 51 detects the FC temperature by the temperature sensor 52. By causing the refrigerant to flow through the second refrigerant circulation path 41B, the refrigerant continuously flows in the fuel cell 10, so that the ECU 51 accurately detects the FC temperature by monitoring the detection value of the temperature sensor 52. It becomes possible.

  In step S90, the ECU 51 determines whether the refrigerant circulation control in the second refrigerant circuit 41B can be stopped (refrigerant circulation stoppage determination unit). In this case, the determination can be made based on whether or not the FC temperature (the refrigerant temperature detected by the temperature sensor 52) is equal to or higher than a predetermined temperature (for example, 15 ° C.). In step S90, when the ECU 51 determines that the FC temperature is not equal to or higher than the predetermined temperature (No), the process returns to step S80, and when it is determined that the FC temperature is equal to or higher than the predetermined temperature (Yes), step S100 is performed. Proceed to

  In step S100, the ECU 51 ends (cancels) the refrigerant circulation restriction control in the first refrigerant circulation path 41A.

  And it progresses to step S110 and ECU51 starts the circulation control which circulates a refrigerant | coolant to 41 A of 1st refrigerant circulation paths. That is, the ECU 51 sets the rotation speed of the motor of the first refrigerant pump 44 to the rotation speed set during normal operation (rated operation). Thereby, the circulation of the refrigerant in the first refrigerant circulation path 41A is started, and the refrigerant discharged from the outlet 10c2 of the refrigerant flow path 10c passes through the pipes c1, c3, c4, and c5 to the inlet 10c1 of the refrigerant flow path 10c. Cycle to return. Further, when the temperature of the refrigerant rises, the flow path is switched by the thermostat 43 and the refrigerant circulates between the fuel cell 10 and the radiator 42.

  In step S120, the ECU 51 stops the refrigerant circulation control in the second refrigerant circulation path 41B. That is, the ECU 51 stops driving the second refrigerant pump 45 so that the refrigerant does not flow into the second refrigerant circulation path 41B.

  In addition, since the check valve 46 is provided in the second refrigerant circulation path 41B, even if the circulation of the refrigerant between the first refrigerant circulation path 41A and the fuel cell 10 is started, the refrigerant is joined to the joining portion. There is no back flow from P2 to the pipe c14 side, and since the second refrigerant pump 45 is stopped, there is no flow from the branch part P1 to the pipe c10 side.

  On the other hand, when the flag is “0” in step S50 (No), in step S130, the ECU 51 starts circulation control for circulating the refrigerant in the first refrigerant circulation path 41A. That is, when the low temperature start-up is not performed, the first refrigerant pump 44 is immediately driven without controlling the flow rate of the refrigerant in the first refrigerant circulation path 41A (without circulating the refrigerant in the second refrigerant circulation path 41B). Then, the refrigerant is circulated through the first refrigerant circulation path 41A.

  In step S140, the ECU 51 detects the FC temperature by the temperature sensor 52.

  As described above, according to the fuel cell system 1A of the first embodiment, the second refrigerant circulation path 41B through which the refrigerant circulates between the fuel cells 10 is provided, and the second refrigerant circulation path is provided at the time of low temperature startup or the like. By circulating the refrigerant through 41B, the FC temperature can be detected by the temperature sensor 52 even when the refrigerant circulation of the first refrigerant circulation path 41A is restricted, and the refrigerant is continuously circulated. It becomes possible to accurately detect the temperature. Therefore, the temperature detection performance can be improved as compared with the conventional case.

  Furthermore, according to the first embodiment, the amount of refrigerant flowing through the second refrigerant circulation path 41B is set to be smaller than the amount of refrigerant flowing through the first refrigerant circulation path 41A. For example, it is possible to prevent the fuel cell 10 from being excessively cooled and obstructing the warm-up of the fuel cell 10.

  Furthermore, according to the first embodiment, the warm refrigerant discharged from the fuel cell 10 is circulated through the heat exchanging parts 24a and 32a and between the reaction gas devices (the gas-liquid separator 24 and the back pressure control valve 32). Since the heat exchange is configured, the temperature of the reaction gas devices can be raised, and when these reaction gas devices are frozen, the ice can be defrosted. Warm-up performance can be improved.

  Further, according to the first embodiment, the refrigerant circulation stop propriety determination means (S90) stops the refrigerant from flowing through the second refrigerant circulation path 41B (S120), so that the amount of heat received by the refrigerant from the reaction gas device is eliminated, and the reaction gas The refrigerant warmed by the device does not return to the fuel cell 10, and the cooling performance when cooling the fuel cell 10 can be improved. And since a refrigerant | coolant is not circulated through the 2nd refrigerant | coolant circulation path 41B unnecessarily, the electric power for driving the 2nd refrigerant | coolant pump 45 can be reduced, and it becomes possible to aim at power saving.

  Furthermore, according to the first embodiment, when the fuel cell 10 is activated at a low temperature by the low temperature activation determining means (S10), the flow rate of the refrigerant in the first refrigerant circulation path 41A is limited, so that the low temperature activation property of the fuel cell 10 is achieved. On the contrary, when the start is not performed at a low temperature, the flow rate of the refrigerant is not limited, so that the fuel cell 10 can be prevented from being overheated, and deterioration of the fuel cell 10 can be suppressed.

  FIG. 3 is a flowchart showing a modification of the refrigerant circulation control in the fuel cell system of the first embodiment, and FIG. 4 is a map showing the relationship between the temperature of the fuel cell and the rotation speed of the first circulation pump. The flowchart shown in FIG. 3 is different in that step S60A in the flowchart shown in FIG. 2 is replaced with step S60B, and steps S100 and S110 are further deleted. Moreover, about the process similar to FIG. 2, the same step code | symbol is shown and the overlapping description is abbreviate | omitted.

  That is, step S60B is a case where it is determined that low temperature startup is to be performed (S50, Yes). At this time, the ECU 51 drives the first refrigerant pump 44 based on the map of FIG. The refrigerant circulation restriction control at is started. In the map shown in FIG. 4, the motor rotational speed is set higher as the FC temperature increases. This map is determined in advance through experiments, simulations, and the like, and warm-up is not impaired when the fuel cell 10 is started at a low temperature, or the fuel cell 10 is overheated when refrigerant circulation control is stopped in the second refrigerant circulation path 41B. The rotation speed is set so as not to become the same.

  In step S70 in FIG. 3, the rotational speed of the second refrigerant pump 45 is controlled by the ECU 51 so that the flow rate of the refrigerant flowing through the second refrigerant circulation path 41B is constant.

  When the detected value of the temperature sensor 52 reaches a temperature at which the circulation control of the refrigerant in the second refrigerant circuit 41B can be stopped (S90, Yes), the ECU 51 stops the driving of the second refrigerant pump 45. Thus, the circulation of the refrigerant in the second refrigerant circulation path 41B is stopped.

(Second Embodiment)
FIG. 5 is an overall configuration diagram showing the fuel cell system of the second embodiment, and FIG. 6 is a map showing the relationship between the temperature of the fuel cell and the opening of the flow control valve. The fuel cell system 1B has a coaxial structure in which the rotation shaft of the air pump 31 and the rotation shaft of the first refrigerant pump 44 are connected to a single motor in the fuel cell system 1A of the first embodiment. That is, when the motor is driven, the air pump 31 and the first refrigerant pump 44 operate together so that air is supplied to the cathode and the refrigerant flows through the first refrigerant circulation path 41A. . The fuel cell system 1B is different from the fuel cell system 1A in that a flow rate control valve 47 is provided in the pipes c6 and c7 between the inlet 10c1 of the refrigerant flow path 10c and the first refrigerant pump 44. In the second embodiment, the flow rate control means is constituted by the flow rate control valve 47 and the ECU 51. In addition, the other components are denoted by the same reference numerals and redundant description is omitted.

  The flow rate control valve 47 restricts the flow of the refrigerant flowing through the first refrigerant circulation path 41A, and is configured by, for example, a butterfly valve capable of adjusting the opening degree, and is connected to the first refrigerant pump 44 via a pipe c6. And connected to the inlet 10c1 of the refrigerant flow path 10c via the pipe c7.

  2 and 3 can be applied to the operation of the fuel cell system 1B of the second embodiment. When the flowchart shown in FIG. 2 is applied, the flow control valve is controlled by the ECU 51 in step S60A. 47 is set to be fully closed (minimum opening). Thereby, even if the 1st refrigerant | coolant pump 44 drives with the air pump 31, a refrigerant | coolant does not flow into 41 A of 1st refrigerant | coolant circulation paths. In step S100, the ECU 51 sets the flow control valve 47 to fully open (maximum opening), and the refrigerant circulation restriction control in the first refrigerant circulation path 41A is terminated (released).

  On the other hand, when the flowchart (modification) shown in FIG. 3 is applied, in step S60B, the opening degree of the flow control valve 47 is set according to the FC temperature by the ECU 51. That is, the opening degree of the flow control valve 47 is controlled based on the map of FIG. 6 to perform the refrigerant circulation restriction control in the first refrigerant circulation path 41A. In the map shown in FIG. 6, the opening degree is set larger as the FC temperature becomes higher. This map is determined in advance through experiments, simulations, and the like, and warm-up is not impaired when the fuel cell 10 is started at a low temperature, or the fuel cell 10 is overheated when refrigerant circulation control is stopped in the second refrigerant circulation path 41B. It is set so that the opening does not become.

  According to the fuel cell system 1B of the second embodiment, the electric power that drives the air pump 31 and the first refrigerant pump 45 by the power generation of the fuel cell 10 even during the refrigerant circulation restriction control in the first refrigerant circulation path 41A. Since the fuel cell 10 is generating power at a higher output, the amount of heat generated by the fuel cell 10 is increased, and the warm-up performance of the fuel cell 10 can be improved.

  In the present embodiment, the refrigerant in the second refrigerant circuit 41B passes through the heat exchange part 32a of the back pressure control valve 32 (reaction gas device) and then the heat exchange part 24a of the gas-liquid separator 24 (reaction gas device). However, the order in which the refrigerant passes is not limited to this, and the refrigerant may flow first to the reaction gas device that needs to be warmed up.

  In addition, the gas-liquid separator 24 and the back pressure control valve 32 have been described as examples of the reaction gas device provided with the heat exchange units 24a and 32a. However, the present invention is not limited to these, and the degree of freezing at a low temperature is not limited thereto. Various changes can be made accordingly. For example, the drain valve 25, the purge valve 26, etc. may be warmed up by providing a heat exchanging part, or although not shown, the humidifier provided in the cathode system 30 is provided with a heat exchanging part. You may make it work.

  Moreover, although the position of the branch part P1 and the junction part P2 of the second refrigerant circulation path 41B is set in the vicinity of the outlet 10c2 and the inlet 10c1 of the refrigerant flow path 10c, the position is not limited to this position. If the position of P1 is upstream of the first refrigerant pump 44, the position of the pipe c3 or the like may be used.

1A, 1B Fuel cell system 10 Fuel cell 24 Gas-liquid separator (reactive gas device)
24a Heat exchange section 32 Back pressure control valve (reactive gas device)
32a Heat exchange part 41A 1st refrigerant circuit 41B 2nd refrigerant circuit 42 Radiator (heat exchanger)
44 1st refrigerant | coolant pump (1st circulation means)
45 Second refrigerant pump (second circulation means)
47 Flow control valve (flow restriction means)
51 ECU (flow rate limiting means, refrigerant circulation stop availability determination means, low temperature activation determination means)
52 Temperature sensor (temperature detection means)
c1 to c7 piping c10 to c14 piping

Claims (3)

A fuel cell that is supplied with reaction gas and generates power;
A reactive gas device through which the reactive gas flows;
A first refrigerant circuit that cools the refrigerant discharged from the fuel cell with a heat exchanger and returns the refrigerant to the fuel cell;
First circulation means for circulating a refrigerant in the first refrigerant circulation path;
A temperature detection means for detecting the temperature of the refrigerant discharged from the fuel cell, and a fuel cell system for controlling the fuel cell based on a detection value of the temperature detection means,
Flow rate limiting means for limiting the flow rate of the refrigerant flowing through the first refrigerant circulation path;
The second refrigerant circuit is branched from the upstream side of the first circulation means and merges with the downstream side of the first circulation means, and the second refrigerant amount is set to be smaller than that of the first refrigerant circulation path. A refrigerant circuit;
Second circulation means for circulating refrigerant in the second refrigerant circulation path;
A heat exchanging part disposed in the second refrigerant circulation path for exchanging heat with the reactive gas device,
The fuel cell system, wherein when the flow rate restricting means restricts the flow rate of the refrigerant flowing through the first refrigerant circulation path, the refrigerant is circulated through the second refrigerant circulation path. Refrigerant circulation stoppage determination unit for determining whether or not to stop the circulation of the refrigerant in the second refrigerant circuit,
When the refrigerant circulation stop propriety determining means determines that the refrigerant circulation is stopped, the refrigerant circulation in the second refrigerant circulation path is stopped and the refrigerant is circulated only in the first refrigerant circulation path. The fuel cell system according to claim 1. Having low temperature start determination means for determining whether to start the fuel cell at a low temperature;
When it is determined that the cold start is determined by the low temperature start determination means, the flow rate limiting means limits the flow rate of the refrigerant flowing through the first refrigerant circulation path and circulates the refrigerant in the second refrigerant circulation path,
3. The fuel cell system according to claim 1, wherein the flow rate of the refrigerant in the first refrigerant circuit is not limited when the low temperature activation determination unit determines that the low temperature activation is not performed.

Images