JP2006049092A - Equipment for controlling fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively remove foreign substance adhering on the sealing part of a check valve prepared in a fuel cell. <P>SOLUTION: The equipment comprises a fuel gas supplying passage L1 for supplying fuel gas to a fuel cell 1, fuel gas reflux passages L2 and L3 for reflux of discharged gas from the fuel cell to the fuel gas supplying passage, a check valve 2 prepared in the fuel gas reflux passages L2 and L3, a fluid injection device 13 and L7 for injecting fluid from the upstream of the fuel gas flow of the check valve 2, and a fluid injection controlling device 20 for removing foreign substance of the check valve by injecting fluid from the fluid injection device. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a control device for a fuel cell.

  The fuel cell generates electricity by reacting hydrogen in the fuel gas with oxygen in the oxidant gas by a reaction between the fuel gas and the oxidant gas. As for the fuel gas, for example, hydrogen is supplied from a high-pressure hydrogen tank to the inlet of the hydrogen electrode of the fuel cell, and the gas after reaction is discharged from the outlet of the hydrogen electrode to the downstream pipe.

  Among the fuel cells, the circulating type is connected to the supply side pipe (the inlet side of the hydrogen electrode) from the discharge side pipe connected to the outlet, after the reaction gas discharged from the outlet of the hydrogen electrode. A circulation passage that circulates in the pipe). In that case, since hydrogen, which is a fuel gas, is also supplied to the supply side pipeline from the high-pressure hydrogen tank, the fuel gas in the supply side pipeline leaks to the discharge side pipeline without passing through the fuel cell body. Need to prevent. Therefore, conventionally, in a circulation type fuel cell, a check valve is provided between the supply side pipe and the discharge side pipe to pass gas from the discharge side to the supply side. The gas is not allowed to pass through to the discharge side.

  FIG. 1 is a diagram showing a schematic configuration of a seal portion of a conventional check valve 2A. This check valve 2 </ b> A is configured inside a cylindrical housing 200. An inlet 201 is provided on the right side wall of the housing 200 and an outlet is provided on the left side wall (not shown). The check valve 2 </ b> A is configured by a fixed valve body 210 and a mover 203 that constitute a part of the housing 200. The right end of the mover 203 constitutes a valve surface 203C, and holds an O-ring 207 as a seal member between the fixed valve body 210 constituting the valve seat 202. In the normal state, the mover 203 is urged toward the valve seat 202 by the spring 204, and the flow of the fluid from the inlet 201 is blocked by the valve face 203C and the valve seat 202 with the O-ring 207 interposed therebetween.

  On the other hand, the space on the left side of the mover 203 in the hollow portion 211 inside the housing 200 constitutes a differential pressure portion, and the mover 203 is moved to the valve seat 202 by the gas in the hollow portion 211 in addition to the elastic force of the spring 204. Press in the direction of. Therefore, when the gas pressure in the hollow portion 211 is higher than the gas pressure on the inlet 201 side, the mover 203 is seated on the valve seat 202 and the seal by the O-ring 207 is maintained.

  On the other hand, when the gas pressure at the inlet 201 is higher than the gas pressure at the hollow portion 211 and exceeds the elastic force of the spring 204, the mover 203 is separated from the valve seat 202, and the seal by the O-ring 207 is performed. The gas on the inlet 201 side flows into the hollow portion 211. The inflowing gas flows to the outlet side (not shown) according to the arrow A shown in FIG.

  When the differential pressure between the inlet 201 side and the hollow portion 211 side becomes a predetermined value or less and the elastic force of the spring 204 exceeds the differential pressure of the gas, the mover 203 is seated on the valve seat 202, and the O-ring The seal by 207 is restored.

  When the check valve 2A having such a configuration is used as a circulation passage for circulating the exhaust gas of the fuel cell, foreign matter enters between the valve surface 203C and the valve seat 202, and in particular, the O-ring 207 and the valve surface 203C. Foreign objects may be bitten between the two. The foreign matter is, for example, fine dust (for example, a fine particle of about several microns) dropped from the inner walls of many pipes constituting the fuel cell, polymer membrane fragments released from the fuel cell stack, part of the electrode, etc. it is conceivable that.

  When such foreign matter adheres to the sealing surface between the O-ring 207 and the valve surface 203C, the sealing performance of the O-ring 207 deteriorates, and the flow of fuel gas from the hollow portion 211 side toward the inlet 201 side. Occurs, and the check performance of the check valve 2A decreases. As a result, normal fuel circulation in the fuel gas circulation system cannot be maintained. In this case, the pressure difference between the inlet 201 side and the outlet side of the check valve 2A disappears, and the inlet and outlet sides of the fuel cell hydrogen electrode have substantially the same gas pressure, so that the power generation of the fuel cell stack can be maintained. It may disappear.

Prior arts related to the present invention are shown in Patent Documents 1 to 4 below. However, none of the documents has proposed a technique for maintaining the sealing performance of the check valve 2A, which is suitable for the configuration of the fuel cell.
JP 2004-111323 A JP 2002-256943 A JP 2004-103505 A JP-A-8-104222

  An object of the present invention is to provide a technique for effectively removing foreign substances adhering to a seal portion of a check valve provided in a fuel cell by utilizing the original configuration of the fuel cell.

  The present invention employs the following means in order to solve the above problems. That is, the present invention provides a fuel gas supply passage for supplying fuel gas to a fuel cell, a fuel gas return passage for returning exhaust gas discharged from the fuel cell to the fuel gas supply passage, and a fuel gas recirculation passage. A check valve provided, fluid injection means for injecting fluid from the upstream side of the check valve fuel gas flow, and removing foreign matter from the check valve by injecting fluid from the fluid injection means And a fuel injection control means.

  Since the fuel cell injects fluid from the upstream side of the check valve fuel gas flow, foreign matter in the check valve can be effectively removed.

  The fuel cell control device further includes a recirculation pump on the fuel gas recirculation passage, and the fluid injection control means stops the fuel gas recirculation by the recirculation pump and injects fluid from the fluid injection means. The foreign matter may be removed from the check valve. In this fuel cell, the foreign matter removal of the check valve is performed in a state where the circulation of the fuel gas by the circulation pump is stopped, so that the foreign matter removal processing and the control of the circulation pump can be performed independently. Therefore, the gas flow by the recirculation pump can be controlled independently of the foreign matter removal processing.

  In the control apparatus for the fuel cell, the check valve further includes a cylindrical portion having a hollow portion, a passage portion for introducing the fuel gas into the hollow portion of the cylindrical portion, and the passage portion to the hollow portion. A valve seat including the opening, a valve body pressed in the valve closing direction against the valve seat by the fuel gas in the hollow portion, and surrounding the opening between the valve seat and the valve body The fluid ejecting means may have an ejection opening for ejecting the fluid toward the seal member in the valve seat portion.

  Since the fuel cell has an injection opening for injecting the fluid toward the seal member in the valve seat portion, foreign matters adhering to the seal portion can be effectively removed.

In the control apparatus for the fuel cell, the fluid ejecting means may be configured such that the first passage into which the high-pressure gas is introduced and the second passage into which the liquid is introduced are merged, and the high-pressure introduced into the first passage. It may have a fluid mixing section that sucks up the liquid from the second passage by a gas flow and generates a fluid in which the high-pressure gas and the liquid are mixed. Since the fuel cell injects a fluid in which high-pressure gas and liquid are mixed, foreign matters can be effectively removed.

  In the control device of the fuel cell, further, a differential pressure between a pressure in the fuel gas circulation passage communicating from the check valve to the fuel gas supply passage and a pressure in the fuel gas circulation passage communicating from the check valve to the circulation pump. And a fluid ejection control means for determining that the foreign matter removal of the check valve is to be performed when the differential pressure detected by the differential pressure detection means is less than or equal to a predetermined differential pressure. May be. According to the present invention, it is possible to determine the necessity of removing foreign matter from the differential pressure between the pressure detection values of the two passages leading to both ends of the check valve. Here, the differential pressure detection detection means may detect the differential pressure by taking the difference between the pressures detected by the two pressure sensors, or detect the differential pressure using the differential pressure sensor as the differential pressure detection means. May be.

  In the control apparatus for the fuel cell, further, a first pressure sensor that detects a pressure in the first fuel gas recirculation passage that communicates from the check valve to the fuel gas supply passage, and the check valve to the recirculation pump At least one second pressure sensor that detects a pressure in the second fuel gas circulation passage that communicates, and the fluid injection control means includes a rate of time change of a pressure detection value of the first pressure sensor or a second pressure sensor You may make it determine whether the foreign material removal of the said check valve is performed from the time change rate of a pressure detection value. According to the present invention, it is possible to determine the necessity of removing foreign matter from the time change of the pressure detection value of one or both of the two passages leading to both ends of the check valve.

  ADVANTAGE OF THE INVENTION According to this invention, the foreign material adhering to the seal | sticker part of the non-return valve provided in the fuel cell can be effectively removed using the structure of a fuel cell.

  Hereinafter, a fuel cell according to the best mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described with reference to the drawings. The configuration of the following embodiment is an exemplification, and the present invention is not limited to the configuration of the embodiment.

<< First Embodiment >>
Hereinafter, a fuel cell according to a first embodiment of the present invention will be described with reference to FIGS. 2 to 7.

FIG. 2 is a system configuration diagram of the fuel cell. The fuel cell includes a fuel cell main body 1 (also referred to as FC), a hydrogen tank 11 that holds high-pressure hydrogen, supplies hydrogen as fuel gas to the fuel cell main body 1, and depressurizes high-pressure hydrogen in the hydrogen tank 11. A low pressure regulator 3; a shutoff valve 12 provided on the outlet side of the low pressure regulator 3 for controlling supply and shutoff of hydrogen; and a hydrogen supply passage L1 for introducing the outlet side of the shutoff valve 12 to the hydrogen electrode inlet of the fuel cell body 1 (Corresponding to a fuel gas supply passage) and a gas-liquid separator 5 connected to the hydrogen electrode outlet of the fuel cell main body 1 by a discharge passage L8 and separated from the exhaust gas, and separated by the gas-liquid separator 5 An auto drain valve 8 that controls the discharge of water, a hydrogen pump 4 that feeds the exhaust gas from which moisture has been separated by the gas-liquid separator 5, and a passage L 2 on the output side of the hydrogen pump 4 are provided. Check valve 2 The exhaust gas is controlled to be discharged and blocked on the passage L3 (L2 and L3 correspond to gas circulation passages) connecting the downstream side of the check valve 2 to the hydrogen supply passage L1 and on the passage L5 branching from the passage L2. It has a shut-off valve 7 and an ECU (Electronic Control Unit) 20 that controls the fuel cell. further,
In this fuel cell, high-pressure hydrogen gas is introduced from the hydrogen tank 11 into the check valve 2 through the branch passage L6 and the shutoff valve 13.

The hydrogen tank 11 holds high-pressure (for example, 8 atm) hydrogen gas. Hydrogen tank 1
1 is connected to the fuel inlet of the fuel cell main body 1 through the low-pressure regulator 3, the shut-off valve 12, and the hydrogen supply passage L 1, and supplies hydrogen to the fuel cell main body 1. The supplied hydrogen is supplied to the hydrogen electrode of each cell of the fuel cell body 1.

  The fuel cell main body 1 is configured by connecting cells including a membrane-electrode assembly (MEA) and a separator in series and stacking them in a plurality of layers. The membrane-electrode assembly includes a hydrogen electrode that separates hydrogen into protons and electrons, an electrolyte membrane that conducts protons generated at the hydrogen electrode to the air electrode, protons and oxygen that are conducted to the air electrode, and an external circuit through an external circuit. And an air electrode for generating water by electrons conducted from. In FIG. 1, the configuration on the air electrode side is omitted.

  The gas-liquid separator 5 separates exhaust gas hydrogen and moisture. A hydrogen pump 4 is connected to the first outlet of the gas-liquid separator 5. The hydrogen from which the droplet water has been separated by the gas-liquid separator 5 is sent by the hydrogen pump 4 to the branched passages L2 and L5. However, since the shutoff valve 7 of the passage L5 is normally closed, the exhaust gas containing hydrogen discharged from the hydrogen pump 4 is sent to the hydrogen supply passage L1 leading to the hydrogen electrode inlet via the check valve 2. . Therefore, the fuel cell main body 1, the gas-liquid separator 5, the hydrogen pump 4, and the check valve 2 form a hydrogen circulation path through the hydrogen supply passage L1, the discharge passage L8, and the passages L2 and L3.

  The hydrogen pump 4 (corresponding to a recirculation pump) sends exhaust gas containing hydrogen into the passage L2. On the other hand, water droplets and exhaust gas separated from hydrogen are discharged out of the fuel cell through the auto drain valve 6.

  The check valve 2 allows the flow of gas from the passage L2 on the output side of the hydrogen pump 4 to the passage L3 leading to the hydrogen supply passage L1, but conversely blocks the flow of gas from the passage L3 to the passage L2. . The passage L2 side with respect to the check valve 2 is referred to as an upstream side of the check valve 2, and the passage L3 side with respect to the check valve 2 is referred to as a downstream side of the check valve 2. As shown in FIG. 2, the passage L3 (corresponding to the first fuel gas circulation passage) is provided with a pressure sensor 6A (corresponding to the first pressure sensor), and detects the pressure P1 downstream of the check valve 2. To do. The passage L2 (corresponding to the second fuel gas circulation passage) is provided with a pressure sensor 6B (corresponding to the second pressure sensor), and detects the pressure P2 upstream of the check valve 2.

  The ECU 20 executes various control programs and controls each component of the fuel cell system such as the shutoff valves 12 and 13, the check valve 2, and the hydrogen pump 4. Moreover, ECU20 monitors the state of each part of fuel cells, such as pressure sensor 6A, 6B, and maintains the driving | running state of a fuel cell in a suitable target state. The ECU 20 includes a CPU, a memory, an input / output interface, and the like. The ECU 20 is connected to control circuits such as the shutoff valves 12 and 13, the check valve 2 and the hydrogen pump 4, and detection circuits such as the pressure sensors 6 </ b> A and 6 </ b> B via an input / output interface (not shown).

  FIG. 3 is a schematic cross-sectional view showing an outline of the structure of the check valve 2. The check valve 2 allows the gas introduced from the inlet 201 to pass in the direction of the outlet 209, but conversely blocks the gas in the direction of the outlet 209 to the inlet 201. This check valve 2 includes a hollow portion 211 that is surrounded by a cylindrical casing 200, a valve seat 202 that is configured to surround an opening in which an inlet 201 opens into the hollow portion 211, and a valve-closed state. The movable valve body 203A seated on the valve seat 202, the spring 204 that presses the movable valve body 203A toward the valve seat 202, and the gas that stays in the hollow portion 211 pressurizes the movable valve body 203A in the valve closing direction. It has a check part 203 </ b> B and a solenoid 212 configured to surround the hollow part 211.

The movable valve body 203A and the check portion 203B constitute the movable element 203, and the hollow portion 211 can be moved in the left-right direction in FIG. Further, the housing 200 has a bottom portion 206 from the hollow portion 211 toward the outlet 209, and the movable element 203 is located at a position where the left end surface of the movable element 203 contacts the bottom portion 206 in the maximum valve open state. Stopped. In the closed state, the movable element 203 stops in a state where the valve surface 203C, which is the right end surface of the movable valve body 203A, is seated on the valve seat 202 via an O-ring 207 (corresponding to a seal member). Therefore, the mover 203 can move in the space 205 portion of the hollow portion 211 between the maximum open state and the closed state.

  Further, when the solenoid 212 is excited, a magnetic field is generated in the cylindrical hollow portion 211 in the axial direction. Due to this magnetic field, the mover 203 receives an electromagnetic force through the hollow portion 211 in the left direction in the figure. When the electromagnetic force exceeds the elastic force of the spring 204 urging rightward and the differential pressure between the gas in the hollow portion 211 and the gas in the inlet 201, the mover 203 moves leftward in the axial direction and is movable. The valve body 203A is separated from the valve seat 202, and the check valve 2 is opened.

  In a state where the solenoid 212 is not excited, the movable element 203 is normally pressed against the valve seat 202 while being urged by the spring 204 and sandwiching the O-ring 207. In addition, the component which combined the needle | mover 203, the valve seat 202, and the solenoid 212 is also called a movable valve.

  FIG. 4 is a diagram illustrating a schematic configuration of a seal portion of the check valve 2 of the present embodiment. This check valve 2 has an O-ring 207 between the valve surface 203C of the mover 203 and the valve seat 202, like the conventional check valve 2A (see FIG. 1). The check valve 2 is different from the conventional check valve 2A in that holes L7 and L8 connected to the branch passage L6 leading to the hydrogen tank 11 are provided through the housing 200, and the O-ring 207 It is in the point opened in the vicinity of the arrangement position.

  FIG. 5 is an enlarged view around the B circle shown in FIG. As shown in FIG. 5, the hole L7 passes through the inside of the housing 200 and extends in the vicinity of the O-ring 207, and toward the contact surface between the O-ring 207 and the valve surface 203C of the mover 203 at the opening L7A. Open.

  The hole L7 is connected to the hydrogen tank 11 via the shutoff valve 13 by the branch passage L6 shown in FIG. 2 (the hole L7 and the shutoff valve 13 correspond to the fluid ejecting means). Therefore, when the ECU 20 opens the shut-off valve 13, high-pressure hydrogen is supplied to the hole L7, and high-pressure hydrogen is discharged from the opening L7A toward the contact surface between the O-ring 207 and the valve surface 203C (this process). ECU3 which performs is equivalent to a fluid ejection control means).

  Note that the ECU 20 excites the solenoid 212 to forcibly move the mover 203 in the valve opening direction by a predetermined distance during high-pressure hydrogen discharge. As a result, the valve surface 203C is separated from the O-ring 207 by a predetermined distance, and a gap is formed. Since the opening L7A of the hole L7 opens toward the contact surface between the O-ring 207 and the valve surface 203C of the mover 203, the hydrogen discharged from the opening L7A is formed by forming a gap therebetween. This increases the certainty of removing the foreign matter bitten by the O-ring 207.

  FIG. 6 shows the relationship between the timing of the high-pressure hydrogen supply control and the movable valve opening / closing control by the ECU 20, the pressure P1 of the pressure sensor 6A, and the pressure P2 of the pressure sensor 6B. The uppermost graph in FIG. 6 shows a control signal for controlling the supply of high-pressure hydrogen, the middle row shows the control signal for opening and closing the movable valve by the mover 203 and the valve seat 202, and the lower row shows the pressures P1 and P2. It shows a change.

  As already described, the pressure sensor 6A is attached to the passage L3 leading to the hydrogen supply passage L1 with respect to the check valve 2, and detects the pressure P1 on the passage L3 side (the check valve downstream side). The pressure sensor 6B is attached to the passage L2 branched from the discharge passage L5, and detects the pressure P2 on the passage L2 side (upstream of the check valve).

  As shown in FIG. 2, in a normal operation state, the shut-off valve 12 is opened, and hydrogen reduced to a predetermined pressure (for example, 2 atmospheres) is supplied to the hydrogen supply passage L <b> 1 through the low pressure regulator 3. This hydrogen is partially consumed at the hydrogen electrode of the fuel cell main body 1, and part of the hydrogen is discharged to a discharge passage L 8 that leads to the gas-liquid separator 5. When the exhaust gas in the exhaust passage L8 and the exhaust gas from which moisture has been removed by the gas-liquid separator 5 increase, the ECU 20 causes the hydrogen pump 4 to move upstream of the check valve 2 (the passages L2 and L5 in FIG. 2). Supply exhaust gas containing hydrogen. On the other hand, in the present embodiment, in a state where the amount of exhaust gas on the side of the discharge passage L8 including the gas-liquid separator 5 is small (for example, a state where the pressure detected by a pressure sensor (not shown) connected to the discharge passage L8 is low), the ECU 20 The hydrogen pump 4 is not operated.

  In a state where there is not enough exhaust gas on the exhaust passage L8 side including such a gas-liquid separator 5, hydrogen is supplied to the hydrogen supply passage L1 side at a predetermined supply pressure via the low-pressure regulator 3, so that the check valve 2 is higher than the pressure on the upstream side (passage L2 side). In such a state, the hollow portion 211 of the check valve 2 forms a differential pressure chamber, and the gas in the hollow portion 211 presses the mover 203 in the direction of the valve seat 202 together with the O-ring 207. The differential pressure on the downstream side is maintained. However, when a foreign object is bitten between the O-ring 207 and the valve surface 203C, the sealing performance in the vicinity of the foreign object is deteriorated, and gas leakage from the downstream side to the upstream side of the check valve 2 occurs.

  The lower graph of FIG. 6 shows an example of detection results of the downstream pressure P1 and the upstream pressure P2 of the check valve 2 in a state where there is not enough exhaust gas on the exhaust passage L8 side, that is, when the hydrogen pump 4 is stopped. Indicates. As shown in this graph, in the normal state close to time T0, the downstream pressure P1 of the check valve 2 maintains a pressure difference equal to or greater than a predetermined value compared to the upstream pressure P2. However, when the sealing performance of the O-ring 207 deteriorates due to the biting of foreign matter, the upstream pressure P2 approaches the downstream pressure P1. For example, at time T1, the pressure difference between the downstream pressure P1 and the upstream pressure P2 is equal to or less than a predetermined threshold value ΔPth1.

  In the fuel cell of the present embodiment, when the pressure difference between the downstream pressure P1 and the upstream pressure P2 becomes equal to or less than the threshold value ΔPth1 while the hydrogen pump 4 is stopped, the ECU 20 starts the foreign substance removal process. In the foreign matter removal process, the ECU 20 drives the mover 203 in the valve opening direction by a predetermined distance (middle in FIG. 6). Driving the movable element 203 in the valve opening direction is simply referred to as opening the movable valve. Further, the ECU 20 opens the shut-off valve 13 and discharges high-pressure hydrogen from the opening L7A toward the O-ring 207 through the branch passage L6 and the hole L7.

  After a predetermined time has elapsed (time T2), the ECU 20 closes the shut-off valve 12, stops the supply of high-pressure hydrogen, stops excitation of the solenoid 212, causes the mover 203 to sit on the valve seat 202, and again Seal with O-ring 207. Further, after a predetermined time has elapsed (time T3), the ECU 20 calculates a pressure difference between the downstream pressure P1 and the upstream pressure P2.

  If the pressure difference is greater than or equal to a predetermined threshold value ΔPth2, the ECU 20 determines that the foreign matter has been removed and returns to normal operation. When the pressure difference is not equal to or greater than the predetermined threshold value ΔPth2, the ECU 20 determines that the removal of the foreign matter is insufficient, and again executes the opening of the movable valve by the excitation of the solenoid 212 and the discharge of high-pressure hydrogen.

  In FIG. 7, the procedure of the foreign material removal process which ECU20 performs in this embodiment is shown. The ECU 20 executes a predetermined control program and executes the control shown in FIG. This process is executed when there is not enough exhaust gas on the discharge passage L8 side (when the hydrogen pump 4 is stopped). In this process, the ECU 20 first detects the pressure P1 on the hydrogen supply passage L1 side (passage L3 (corresponding to the first fuel gas circulation passage) side, check valve 2 downstream side) (S1).

  Next, the ECU 20 detects the pressure P2 on the discharge passage L5 side (passage L2 (corresponding to the second fuel gas circulation passage) side, check valve 2 upstream side) (S2). Then, the ECU 20 determines whether or not the pressure difference between P1 and P2 exceeds a predetermined threshold value ΔPth1 (S3).

  When the pressure difference exceeds the threshold value ΔPth1, the ECU 20 ends the process. On the other hand, when the pressure difference does not exceed the threshold value ΔPth1, the ECU 20 opens the movable valve of the check valve 2 (S5). Further, the ECU 20 opens the shut-off valve 13 and ejects high-pressure hydrogen from the opening L7A (S6). Then, the ECU 20 maintains the high-pressure hydrogen ejection for a predetermined discharge period, and then closes the movable valve of the check valve 2 (S7).

  Next, the ECU 20 waits for a predetermined time to elapse (S8), and detects the pressure P1 on the hydrogen supply passage L1 side (S9). Further, the ECU 20 detects the pressure P2 on the discharge passage L5 side (S10).

  Then, the ECU 20 determines whether or not the pressure difference between P1 and P2 exceeds a predetermined threshold value ΔPth2 (S11). As the threshold value ΔPth2, a value larger than the threshold value ΔPth1 is normally set.

  If the pressure difference exceeds the predetermined threshold value ΔPth2, the ECU 20 determines that the foreign matter has been removed, and ends the process. On the other hand, when the pressure difference does not exceed the predetermined threshold value ΔPth2, the ECU 20 returns the control to S5, and executes foreign matter removal again.

  As described above, according to the fuel cell of this embodiment, when the pressure P1 on the downstream side of the check valve 2 and the pressure P2 on the upstream side are detected and the differential pressure is not sufficient, the check valve 2 It is judged that the non-return performance is deteriorated. In such a case, high-pressure hydrogen is discharged near the contact portion between the O-ring 207 constituting the seal portion of the check valve 2 and the valve surface 203C of the mover 203 to remove foreign matter. In this case, as shown in the middle stage of FIG. 6 or S5 of FIG. 7, the movable valve of the check valve 2 may be opened by a predetermined value. When it is determined that the differential pressure between P1 and P2 is sufficiently maintained after the predetermined time has elapsed, the foreign matter removal process is terminated. On the other hand, when it is determined that the differential pressure between P1 and P2 cannot be maintained, the foreign matter removal is repeated again. By such a procedure, it is possible to recover from the deterioration state of the check performance due to the foreign object biting into the seal portion of the check valve 2.

  As described above, the fuel cell according to the present embodiment detects the deterioration of the sealing performance of the check valve 2 due to the foreign matter while the hydrogen pump 4 is stopped, and removes the foreign matter. However, in general, foreign matter removal is not limited to such a procedure. For example, as described above, while the hydrogen pump 4 is stopped, the pressure P1 downstream of the check valve 2 and the pressure P2 upstream of the check valve 2 are measured, and deterioration of the sealing performance is detected from the pressure difference. Thereafter, the foreign matter removal process may be executed after the hydrogen pump 4 is started.

  By driving the hydrogen pump 4, the gas pressure P <b> 2 upstream of the check valve 2 on the output side of the hydrogen pump 4 increases and exceeds the sum of the gas pressure P <b> 1 upstream of the check valve 2 and the elastic force of the spring 204. In this case, the movable valve is opened, and a forward gas flow from the upstream side to the downstream side of the check valve 2 is generated. The gas flow may improve the effect of removing foreign matter.

  However, when such a procedure is adopted, the flow rate of the fuel gas flowing through the passages L3 and L1 and the fuel cell main body 1 is increased by the flow of the gas fed from the hydrogen pump 4, and the fuel gas stays in the fuel main body 1. There is a possibility that time will be reduced and the power generation efficiency of the fuel cell main body 1 will be reduced.

  On the other hand, in this embodiment, since the foreign matter is removed by discharging high pressure hydrogen from the opening L7A to the seal portion, it is not necessary to start the hydrogen pump 4 daringly. Start and stop can be controlled. Therefore, in the fuel cell of the present embodiment, the foreign matter at the seal portion of the check valve 2 can be removed without reducing the residence time of hydrogen, which is the fuel gas, in the fuel cell main body 1.

  Furthermore, in the configuration of the present embodiment, high pressure hydrogen is locally injected from the opening L7A, so that the foreign matter is removed by the gas flow from the upstream side of the check valve 2 fed from the hydrogen pump side. There is little influence on the speed of the flow of hydrogen supplied to the fuel cell main body 1 through the passage L2 and the hydrogen supply passage L1 (the influence of increasing the speed is small). Therefore, the foreign matter at the seal portion of the check valve 2 can be removed without shortening the residence time of the fuel gas, hydrogen, in the fuel cell main body 1.

  In the above-described embodiment, a processing example is shown in which high-pressure hydrogen is discharged while the movable valve of the check valve 2 is once opened when the foreign substance removal processing is executed. However, the implementation of the present invention is not limited to such processing. That is, high-pressure hydrogen may be discharged to the seal portion while the mover 203 is pressed against the O-ring 207. As for the exhaust gas of the fuel cell, even when moisture is removed by the gas-liquid separator 5, the exhaust gas discharged into the passages L2 and L5 contains a small amount of moisture. This is because foreign matter can be removed even if high-pressure hydrogen is discharged to the seal portion in the closed state.

  In the above-described embodiment, the downstream pressure P1 and the upstream pressure P2 of the check valve 2 are detected by the two pressure sensors 6A and 6B, and the seal is determined depending on whether or not the pressure difference exceeds a predetermined threshold value. The presence or absence of foreign matter adhesion to the part was determined. However, instead of such a configuration, a differential pressure gauge that detects the differential pressure between the downstream side and the upstream side of the check valve 2 is used, and depending on whether or not the differential pressure exceeds a predetermined threshold, The presence / absence of foreign matter adhesion and therefore the necessity of foreign matter removal processing may be determined.

<< Second Embodiment >>
Hereinafter, a fuel cell according to a second embodiment of the present invention will be described with reference to FIG. In the said 1st Embodiment, the fuel cell which discharges high pressure hydrogen to a seal part when the sealing performance of the non-return valve 2 deteriorated was demonstrated. In the first embodiment, when the hydrogen pump 4 is stopped, the deterioration of the sealing performance is detected based on the pressure difference between the pressure P1 on the downstream side of the check valve 2 and the pressure P2 on the upstream side.

  In the present embodiment, an example of a fuel cell that detects the deterioration of the sealing performance of the check valve 2 and executes foreign matter removal processing regardless of whether or not the hydrogen pump 4 is in operation will be described. Other components and operations in the present embodiment are the same as those in the first embodiment. Therefore, the same components are denoted by the same reference numerals and the description thereof is omitted. Further, the drawings in FIGS. 1 to 7 are referred to as necessary.

  While the hydrogen pump 4 is in operation, the pressure P2 upstream of the check valve 2 increases with time due to the gas sucked up by the hydrogen pump 4. Therefore, simply by detecting the pressure difference between the pressure P1 downstream of the check valve 2 and the pressure P2 upstream, whether the pressure difference is reduced due to the output of the hydrogen pump 4 or downstream due to deterioration of the sealing performance. It may not be possible to determine whether this is due to leakage from the upstream side.

Therefore, in this embodiment, the rate of change per unit time of the pressure P2 is calculated from the history of the measured value of the pressure P2 upstream of the check valve 2, and if the rate of change is within a predetermined range, the sealing performance is deteriorated. Judge that there is no. That is, when the pressure P2 on the upstream side of the check valve 2 changes at a rate of change larger than the rate of change caused by the displacement of the hydrogen pump 4, it can be estimated that there is a deterioration in the sealing performance.

  FIG. 8 is a flowchart showing the processing of the ECU 20 in the present embodiment. In this process, the ECU 20 first refers to a history of measured values of the pressure P2 on the passage L2 side, that is, on the upstream side of the check valve 2. Such a history of actual measurement values is recorded in a memory (not shown) in the ECU 20 for a predetermined period. Then, the ECU 20 calculates the rate of change ΔP / ΔT per unit time of the pressure P2 from the history of the measured values (S1A).

  Next, the ECU 20 determines whether or not the rate of change ΔP / ΔT per unit time of the pressure P2 is smaller than a predetermined threshold Rth (S3A). Here, the threshold value Rth may be obtained experimentally from, for example, a change in the measured value of the pressure P2 during operation of the fuel cell with the hydrogen pump stopped. Further, during operation of the hydrogen pump 4, a value obtained by adding a pressure change based on the displacement of the hydrogen pump 4 to the value obtained experimentally may be used.

  When the change rate ΔP / ΔT is smaller than the predetermined threshold value Rth, the ECU 20 ends the foreign matter removal process on the assumption that there is no deterioration in the sealing performance. On the other hand, when the change rate ΔP / ΔT is larger than the predetermined threshold value Rth, the ECU 20 executes the processing from S5 to S8, as in the case of the first embodiment. Since these procedures are the same as those in the first embodiment, description thereof is omitted.

  Thereafter, the ECU 20 again refers to the history of the measured value of the pressure P2 on the passage L2 side, that is, on the upstream side of the check valve 2, and calculates the change rate ΔP / ΔT per unit time (S9A). Then, the ECU 20 determines again whether or not the rate of change ΔP / ΔT per unit time of the pressure P2 is smaller than a predetermined threshold value Rth (S11A). When the change rate ΔP / ΔT is smaller than the predetermined threshold value Rth, the ECU 20 ends the foreign matter removal process on the assumption that the deterioration of the sealing performance has been eliminated. On the other hand, when the change rate ΔP / ΔT is larger than the predetermined threshold value Rth, the ECU 20 returns the control to S5 and repeats the foreign substance removal process.

  As described above, according to the fuel cell of the present embodiment, the deterioration of the sealing performance of the check valve 2 is detected and bitten by the O-ring 207 regardless of whether the hydrogen pump 4 is in operation. Foreign matter can be removed.

  In the present embodiment, the change rate ΔP / ΔT per unit time is calculated with reference to the history of the measured value of the pressure P2 upstream of the check valve 2. However, instead of such a procedure, the change rate ΔP / ΔT per unit time may be calculated by referring to the history of the actual measurement value of the pressure P1 downstream of the check valve 2. In that case, the hydrogen supply flow rate from the hydrogen tank 11 and the gas flow rate flowing into the fuel cell main body 1 (hereinafter referred to as gas main body inflow amount) may be measured. Then, the change rate ΔP / ΔT per unit time may be calculated by correcting the change amount of the measured value of the pressure P1 based on the hydrogen supply flow rate and the gas main body inflow amount.

  Further, the shutoff valve 12 is closed, the pressure P1 downstream of the check valve 2 is measured in the absence of hydrogen supply, and the sealing performance depends on whether the rate of change (decrease rate) exceeds a predetermined threshold. Deterioration may be determined. An inlet valve (not shown) that shuts off hydrogen flowing into the fuel cell main body 1 is provided, and the pressure P1 downstream of the check valve 2 is measured with the inlet valve closed, and the rate of change (decrease) The deterioration of the sealing performance may be determined based on whether or not the ratio exceeds a predetermined threshold value.

  In both the first embodiment and the second embodiment, the deterioration of the sealing performance is detected from the detected pressure values of the pressure sensors 6A, 6B, etc., and the foreign matter removal process is executed. However, the implementation of the present invention is not limited to such a procedure, and the foreign matter removal process may be executed regardless of the deterioration of the sealing performance. For example, the ECU 20 may execute the step S6 shown in FIG. 7 or FIG. 8 or the steps S5 to S7 at a predetermined interval.

<< Third Embodiment >>
Hereinafter, a fuel cell according to a third embodiment of the present invention will be described with reference to FIG. In the first embodiment or the second embodiment, the fuel cell that discharges high-pressure hydrogen to the seal portion when the sealing performance of the check valve 2 deteriorates has been described. In this embodiment, a fuel cell that discharges water separated from exhaust gas by the gas-liquid separator 5 together with high-pressure hydrogen in such a case will be described. Other components and operations in the present embodiment are the same as those in the first embodiment. Therefore, the same components are denoted by the same reference numerals and the description thereof is omitted. Further, the drawings in FIGS. 1 to 7 are referred to as necessary.

  FIG. 9 is a system configuration diagram of the fuel cell according to the third embodiment. In this fuel cell, a nozzle 14 (corresponding to a fluid mixing portion) is provided on a branch passage L6 connected to a hole L7 of the check valve 2. The nozzle 14 has a connection portion in which a gas passage through which high-pressure hydrogen passes and a liquid passage through which water is introduced are connected in a T shape. When high-pressure hydrogen is passed through the gas passage of the nozzle 14, a negative pressure is generated in the liquid passage portion, and water in the liquid passage is sucked into the gas passage and mixed with high-pressure hydrogen. Then, the fluid in which water and high-pressure hydrogen are mixed is discharged to the hole L7 (see FIGS. 4 and 5) of the check valve 2, and is passed from the opening L7A to the seal portion formed by the O-ring 207 and the valve face 203C. Discharged. As shown in FIG. 8, the liquid passage of the nozzle 14 may be connected to the water discharge side of the gas-liquid separator 5 (opening leading to the water storage portion) by a liquid passage L10.

  In the fuel cell having such a configuration, the foreign matter removal process as shown in FIGS. 6 and 7 can be performed to remove the foreign matter from the seal portion as in the case of the first embodiment. Furthermore, in the structure of this embodiment, since water is discharged together with high-pressure hydrogen, the effect of removing foreign matters can be further enhanced. Further, as shown in the middle stage of FIG. 6 of the first embodiment or S5 of FIG. 7, it is not always necessary to open the movable valve. That is, the foreign matter can be efficiently removed even when the mover 203 presses the O-ring 207 due to the lubricating effect of the droplets.

It is a figure which shows schematic structure of the seal part of the conventional check valve. 1 is a system configuration diagram of a fuel cell according to a first embodiment. It is a schematic sectional drawing which shows the outline | summary of the structure of the non-return valve which concerns on 1st Embodiment. It is a figure which shows schematic structure of the seal | sticker part of the non-return valve which concerns on 1st Embodiment. Enlarged view of the seal part It is a figure which shows the relationship between the timing of a high pressure hydrogen supply control and movable valve opening / closing control, and the detected value of a pressure sensor. It is a flowchart which shows the procedure of the foreign material removal process which concerns on 1st Embodiment. It is a flowchart which shows the procedure of the foreign material removal process which concerns on 2nd Embodiment. It is a system block diagram of the fuel cell which concerns on 3rd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel cell main body 2 Check valve 3 Low pressure regulator 4 Hydrogen pump 5 Gas-liquid separator 6A, 6B Pressure sensor 7 Drain valve 8 Auto drain valve 11 Hydrogen tank 12, 13 Shut-off valve 14 Nozzle L1 Hydrogen supply passage L2, L3, L5 Passage L6 Branch passage L8 Discharge passage

Claims (6)

A fuel gas supply passage for supplying fuel gas to the fuel cell;
A fuel gas recirculation passage for recirculating exhaust gas discharged from the fuel cell to the fuel gas supply passage;
A check valve provided in the fuel gas circulation passage;
Fluid injection means for injecting fluid from the upstream side of the flow of fuel gas of the check valve;
And a fluid injection control means for removing foreign matter from the check valve by injecting fluid from the fluid injection means. The fuel cell control device according to claim 1, further comprising a recirculation pump on the fuel gas recirculation passage,
2. The fuel cell control apparatus according to claim 1, wherein the fluid injection control means removes foreign matter from the check valve by stopping the circulation of fuel gas by the circulation pump and injecting fluid from the fluid injection means. The fuel cell control device according to claim 1, further comprising:
The check valve includes a tubular portion having a hollow portion, a passage portion for introducing the fuel gas into the hollow portion of the tubular portion, and a valve seat portion including an opening of the passage portion to the hollow portion, A valve body that is pressed against the valve seat portion by the fuel gas in the hollow portion in a valve closing direction; and a seal member that is disposed so as to surround the opening between the valve seat portion and the valve body. And
The said fluid injection means is a control apparatus of the fuel cell which has the injection opening which injects the said fluid toward the said seal member in the said valve seat part. The fuel cell control device according to any one of claims 1 to 3, further comprising:
The fluid ejecting means is configured by joining a first passage through which high-pressure gas is introduced and a second passage through which liquid is introduced, and the fluid is injected from the second passage by the flow of high-pressure gas introduced into the first passage. A fuel cell control device comprising a fluid mixing section that sucks up a liquid and generates a fluid in which the high-pressure gas and the liquid are mixed. The fuel cell control device according to any one of claims 2 to 4, further comprising:
A differential pressure detection means for detecting a differential pressure between a pressure in the fuel gas circulation passage communicating from the check valve to the fuel gas supply passage and a pressure in the fuel gas circulation passage communicating from the check valve to the circulation pump;
The fluid injection control means is a fuel cell control device that determines to remove foreign matter from the check valve when the differential pressure detected by the differential pressure detection means is not more than a predetermined differential pressure. The fuel cell control device according to any one of claims 2 to 4, further comprising:
A first pressure sensor for detecting a pressure in a first fuel gas circulation passage communicating from the check valve to a fuel gas supply passage; and a second fuel gas circulation passage communicating from the check valve to the circulation pump. Comprising at least one second pressure sensor for detecting pressure;
The fluid injection control means determines whether or not to remove foreign matter from the check valve based on the time change rate of the pressure detection value of the first pressure sensor or the time change rate of the pressure detection value of the second pressure sensor. Battery control device.

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