JP2009140746A - Fuel cell system, and control method of fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent such a case that hydrogen diffused in an oxidizer gas flow passage exists in the surrounding of a flow rate detecting means for detecting a flow rate of an oxidizer gas. <P>SOLUTION: An air flow passage in a suction air module 20 includes a first flow passage part A and a second flow passage part B independent from each other, and these flow passage parts lead to a fuel cell stack 1 after confluence. An open-close valve 24b capable of blocking either one of the first flow passage part A and the second flow passage part B is installed at this air flow passage. Moreover, a first flow rate sensor 41 for detecting the flow rate of air flowing in this flow passage in the energized state is installed upstream of the open-close valve 24b and at the first flow passage part A, while a second flow rate sensor 42 for detecting the flow rate of air flowing in this flow passage in the energized state is installed upstream of the open-close valve 24b and at the second flow passage part B. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel cell system and a control method thereof.

  Conventionally, a fuel gas (for example, hydrogen) is supplied to the fuel electrode, and an oxidant gas (for example, air) is supplied to the oxidant electrode, and these gases are reacted electrochemically to generate power. There is known a fuel cell system including a fuel cell for performing the above.

For example, in Patent Document 1, from the viewpoint of suppressing deterioration of the fuel cell, when the fuel cell system is stopped, oxygen in the oxidant electrode of the fuel cell is consumed and replaced with hydrogen and an inert gas (for example, nitrogen). A technique for performing stop processing is disclosed.
JP 2005-518632 A

  By the way, according to the technique disclosed in Patent Document 1, there is a possibility that the fuel gas present in the oxidant electrode diffuses into the oxidant gas flow path for supplying the oxidant gas during the stop period. The oxidant gas flow path is provided with a flow rate detection means that operates by energizing a detection element provided in the flow path in order to detect the flow rate of the oxidant gas. There is a possibility that a high concentration of hydrogen is present around the detection means.

  The present invention has been made in view of such circumstances, and an object of the present invention is to suppress a situation in which hydrogen diffused in the oxidant gas flow path exists around the flow rate detection means for detecting the flow rate of the oxidant gas. There is.

  In order to solve this problem, in the fuel cell system of the present invention, the oxidant gas flow path includes a first flow path section and a second flow path section independent from each other, and these flow path sections merge. Later, it leads to a fuel cell. The air flow path is provided with a blocking means capable of blocking either the first flow path portion or the second flow path portion. Further, a first flow rate detection that detects the flow rate of the oxidant gas that flows through the flow path portion (first flow path portion) in an energized state in the first flow path portion upstream of the blocking means. Means are provided, and the flow rate of the oxidant gas flowing through the flow path (second flow path portion) in the energized state is detected in the second flow path portion upstream of the blocking means. Second flow rate detecting means is provided.

  According to the present invention, the first and second flow path portions can be selectively blocked by the blocking means. Therefore, even when the fuel gas has diffused from the fuel cell side during the stop period, the amount of fuel gas that reaches the flow rate detecting means in the flow path portion on the blocked side is suppressed. As a result, it is possible to suppress a situation in which the fuel gas exists at a high concentration around the flow rate detection means. Further, it is possible to suppress a situation in which the flow rate detecting means is energized in the state where the high-concentration fuel gas is present at the time of starting the system. Therefore, the safety at the time of starting can be improved.

  FIG. 1 is a block diagram showing the overall configuration of a fuel cell system according to an embodiment of the present invention. The fuel cell system is mounted on, for example, a vehicle that is a moving body, and the vehicle is driven by electric power supplied from the fuel cell system.

  The fuel cell system includes a fuel cell stack 1. The fuel cell stack 1 is configured by stacking a plurality of fuel cells each functioning as a power generation element. Each fuel cell is provided with a catalyst (for example, platinum) layer on both sides of a solid polymer electrolyte membrane, and a fuel cell structure in which a fuel electrode and an oxidant electrode are opposed via this catalyst layer is sandwiched between separators. Configured. In the fuel cell stack 1, in each fuel cell, the fuel gas is supplied to the fuel electrode, and the oxidant gas is supplied to the oxidant electrode, whereby these reaction gases are caused to react electrochemically. Generate generated power. In this embodiment, a case where hydrogen is used as the fuel gas and air is used as the oxidant gas will be described.

  The fuel cell system further includes a hydrogen system for supplying hydrogen to the fuel cell stack 1 and an air system for supplying air to the fuel cell stack 1.

  In the hydrogen system, hydrogen, which is a fuel gas, is stored in a fuel tank 10 (for example, a high-pressure hydrogen cylinder), and is supplied from the fuel tank 10 to the fuel cell stack 1 via the hydrogen supply flow path L1. Specifically, a fuel tank original valve (not shown) is provided downstream of the fuel tank 10, and when the fuel tank original valve is opened, the high-pressure hydrogen gas from the fuel tank 10 flows downstream thereof. The pressure is mechanically reduced to a predetermined pressure by a pressure-reducing valve (not shown) provided in the. The depressurized hydrogen gas is further depressurized by a hydrogen pressure regulating valve 11 provided downstream of the depressurizing valve, and then supplied to the fuel cell stack 1. The hydrogen pressure supplied to the fuel cell stack 1 can be adjusted by controlling the opening of the hydrogen pressure regulating valve 11.

  Exhaust gas from the fuel electrode (gas containing unused hydrogen) is discharged from the fuel cell stack 1 to the hydrogen circulation passage L2. The other end of the hydrogen circulation flow path L2 is connected to the hydrogen supply flow path L1 on the downstream side of the hydrogen pressure regulating valve 11, and a gas such as a hydrogen circulation pump 12 is provided in the hydrogen circulation flow path L2. Circulation means are provided. By driving the hydrogen circulation pump 12, the exhaust gas from the fuel electrode is circulated to the fuel cell stack 1 via the hydrogen circulation flow path L2.

  By the way, in the case of using air as the oxidant gas, since impurities in the air permeate from the oxidant electrode to the fuel electrode, the impurities in the hydrogen circulation passage L2 including the fuel electrode increase and the hydrogen partial pressure decreases. Tend to. Here, the impurity is a non-fuel gas component other than hydrogen which is a fuel gas, and a typical example is nitrogen. If the amount of nitrogen is excessively increased, the output from the fuel cell stack 1 is disadvantageously reduced. Therefore, it is necessary to manage the amount of nitrogen in the hydrogen circulation passage L2 including the fuel electrode. Therefore, the hydrogen circulation flow path L2 is provided with a purge flow path L3 for discharging the circulation gas to the outside. The purge flow path L3 is provided with a purge valve 13. By adjusting the opening amount of the purge valve 13, the amount of nitrogen discharged to the outside through the purge flow path L3 can be adjusted. Thereby, the nitrogen amount existing in the fuel electrode and the hydrogen circulation passage L2 is managed so that the power generation performance can be maintained. Further, a hydrogen combustor 14 is provided in the purge flow path L3, and hydrogen contained in the gas is combusted by the hydrogen combustor 14.

  In the air system, the air, which is an oxidant gas, is pressurized when the atmosphere is taken in by the compressor (oxidant gas supply means) 30 via the intake module 20, and the fuel cell stack 1 via the air supply flow path L4. To be supplied. Exhaust gas from the oxidant electrode (air in which oxygen has been consumed) is discharged to the outside through the air discharge flow path L5. An air pressure adjusting valve 31 that adjusts the pressure of the air supplied to the fuel cell stack 1 is provided in the air discharge flow path L5.

  FIG. 2 is an explanatory diagram schematically showing the configuration of the intake module 20. The intake module 20 is mainly composed of an intake duct 21, a resonator 22, a filter 23, a flow dividing unit 24, and a silencer 25, and a fuel cell is formed by these individual elements via an air supply flow path L4. An air flow path leading to the stack 1 is configured. Outside air (air) taken in from the intake duct 21 is guided to the filter 23 via a conduit to which the resonator 22 is attached. A shunt unit 24 and a silencer 25 are sequentially provided at the subsequent stage of the filter 23, and the air that has passed through the filter 23 passes through the shunt unit 24 and the silencer 25 and is introduced into the air supply flow path L 4 that is connected to the silencer 25. Is done.

  The intake duct 21 is a duct (conduit) that guides air to the filter 23. The resonator 22 is configured by a box having a predetermined space, and has a function of reducing intake noise by using this space as a resonance space. The filter 23 includes a dust filter that captures relatively coarse dust in the air and a chemical filter that removes chemical substances (NOx, SOx, etc.) in the air, and these filters are accommodated in a case. ing. The introduced air is purified by a filter of dust and gas that deteriorates the catalyst of the fuel cell. The diversion unit 24 has a function of diverting and flowing the passing air, and details thereof will be described later. The silencer 25 absorbs intake noise by a sound absorbing material such as glass wool or a sound absorbing structure.

  FIG. 3 is a schematic diagram showing the configuration of the flow dividing unit 24 from above. A part of the air flow path is constituted by a cylindrical main body portion in the diversion unit 24, and a plate-like shape extending in the air flow direction (axial direction of the flow path) is provided at the center of the main body portion. The dividing plate 24a is arranged. The flow path of the main body is divided into two parallel spaces by the dividing plate 24a, and two flow paths (first and second flow paths) A and B that are independent from each other are configured. As will be described later, the first and second flow path portions A and B are provided with flow rate sensors 41 and 42 that flow through the flow paths. In the present embodiment, the dividing plate 24a is configured to divide not only the flow dividing unit 24 but also the flow path in the filter 23 located on the upstream side thereof.

  At the end (downstream end) of the dividing plate 24a, the first and second flow path portions A and B merge, and the end has a semicircular shape corresponding to the cross-sectional shape of the main body. An on-off valve (shut-off means) 24b having a valve body is arranged. The on-off valve 24b has a function of adjusting the opening area of the first flow path part A or the second flow path part B by operating a valve body by driving an actuator (not shown). Any one of the first channel portion A and the second channel portion B can be blocked. Further, on the downstream side of the diversion unit 24, specifically, on the downstream side of the opening / closing valve 24b, the turbulence suppressing device 24c as turbulence suppressing means for suppressing turbulent flow generated downstream of the opening / closing valve 24b. Is provided.

  FIG. 4 is an explanatory view schematically showing the operation of the on-off valve 24b. When the valve body of the on-off valve 24b is operated to the first flow path portion A side, the valve body moves to a position that is perpendicular to the flow of the first flow path portion A (first maximum movable position). In this case, the first flow path portion A is blocked (closed) by the valve body (see FIG. 5A), and only the second flow path portion B is opened, and the second flow path portion B Only the air flows. On the other hand, when the valve body of the on-off valve 24b is operated to the second flow path portion B side, the valve body is movable to a position that is perpendicular to the flow of the second flow path portion B (second maximum movable position). ). In this case, the second flow path portion B is blocked (closed) by the valve body (see FIG. 5B), and only the first flow path portion A is opened, so that the first flow path portion A Only the air flows.

  On the other hand, when the valve body of the on-off valve 24b is operated to the neutral position, that is, the state parallel to the dividing plate 24a, the first and second flow path portions A and B are opened (same as above). (Refer figure (a)). In this case, air flows through the first and second flow path portions A and B, respectively. Further, when the valve body of the on-off valve 24b is operated between the first maximum movable position and the neutral position, the opening area of the first flow path portion A is partially blocked by the valve body. Thereby, the flow of the said 1st flow-path part A can be partially controlled. Similarly, when the valve body of the on-off valve 24b is operated between the second maximum movable position and the neutral position, the opening area of the second flow path portion B is partially blocked by the valve body, Thus, the flow of the second flow path part B can be partially restricted.

  Referring again to FIG. 1, a power extraction device 2 is connected to the fuel cell stack 1. The power extraction device 2 is controlled by a control unit 40 described later, and supplies the electric power generated in the fuel cell stack 1 to the electric motor 3 that drives the vehicle.

  The control unit 40 has a function of controlling the entire system in an integrated manner, and controls the operating state of the fuel cell stack 1 by operating according to the control program. As the control unit 40, a microcomputer mainly composed of a CPU, a ROM, a RAM, and an I / O interface can be used. The control unit 40 performs various calculations based on the state of the system, and outputs the calculation results to various actuators (not shown) as control signals. The hydrogen pressure regulating valve 11, the hydrogen circulation pump 12, the purge valve 13, various elements such as the compressor 30, the air pressure adjusting valve 31, and the power take-out device 2 are controlled.

  Sensor signals from various sensors and the like are input to the control unit 40 in order to detect the state of the system. As shown in FIG. 3, the first flow rate sensor (first flow rate detection means) 41 is provided in the first flow path portion A which is one flow path in the diversion unit 24, and this flow path portion. The flow rate of air flowing through A is detected. As shown in FIG. 3, the second flow rate sensor (second flow rate detection means) 42 is provided in the second flow path portion B which is the other flow path in the diversion unit 24. The flow rate of the air flowing through B is detected. As the individual flow sensors 41 and 42, heating resistance type flow sensors can be used. This heating resistance type flow sensor controls the current flowing through the heating resistor so that the temperature of the heating resistor becomes a predetermined temperature higher than the temperature sensing resistor that detects the temperature of the passing air. The air flow rate is detected from the current flowing through the.

  In relation to the present embodiment, the control unit 40 controls the operating state of the on-off valve 24b in the flow dividing unit 24 according to the operating state of the system, and the first flow sensor 41 and the second flow sensor 42 are controlled. Control the energization state.

  FIG. 5 is a flowchart showing the procedure of the control method of the fuel cell system according to the embodiment of the present invention. The process shown in this flowchart is called together with the input of an on signal of the ignition switch of the vehicle, and shows a series of processing procedures from start to stop executed by the control unit 40. Note that on the assumption that this processing is performed, that is, when the system is stopped, the on-off valve 24b is controlled to the first maximum movable position, and the first flow path portion A is blocked (closed) by the valve body. Yes.

  First, in step 1 (S1), the position control of the on-off valve 24b is performed. Specifically, the control unit 40 controls the open / close valve 24b to the second maximum movable position. As a result, the first flow path part A is opened and the second flow path part B is blocked.

  In Step 2 (S2), supply of the reaction gas, that is, hydrogen and oxygen is started. At the same time, the control unit 40 starts increasing the rotational speed of the compressor 30. In step 3 (S3), the first flow sensor 41 is energized.

  In step 4 (S4) following step 3, it is determined whether or not the increased rotational speed of the compressor 30 has reached a first rotational speed determination value Rth1 described later. The rotational speed of the compressor 30 may be actually detected using a sensor or the like, but a rotational speed command value for the compressor 30 may be referred to. If the determination in step 4 is affirmative, that is, if the rotation speed of the compressor 30 has reached the first rotation speed determination value Rth1, the process proceeds to step 5 (S5). On the other hand, if a negative determination is made in step 4, that is, if the rotation speed of the compressor 30 has not reached the first rotation speed determination value Rth1, the process of step 4 is executed again after a predetermined time.

  In step 5, position control of the opening / closing valve 24b is performed. Specifically, the control unit 40 monitors the rotational speed of the compressor 30 so that the valve body of the on-off valve 24b returns to the neutral position at the timing when the second rotational speed determination value Rth2 is reached. The position of the valve body of the on-off valve 24b between the second maximum movable position and the neutral position is controlled in accordance with the difference between the rotation speed of the first rotation speed and the second rotation speed determination value Rth2. Here, the second rotational speed determination value Rth2 is set to a value larger than the above-described first rotational speed determination value Rth2, and details thereof will be described later.

  In step 6 (S6), it is determined whether or not the increased rotational speed of the compressor 30 has reached the second rotational speed determination value Rth2. If the determination in step 6 is affirmative, that is, if the rotation speed of the compressor 30 has reached the second rotation speed determination value Rth2, the process proceeds to step 7 (S7). On the other hand, if a negative determination is made in step 6, that is, if the rotation speed of the compressor 30 has not reached the second rotation speed determination value Rth2, the process of step 5 is executed again after a predetermined time.

  In step 7 (S7), it is determined whether or not the second flow sensor 42 is energized. Based on the detection result of the first flow rate sensor 41, the control unit 40 estimates the flow rate of the air that has flowed through the second flow path part B from the timing when the second flow path part B is opened, and this estimation result. Based on the above, it is determined whether or not energization of the second flow sensor 42 is permitted. Specifically, when the amount of air corresponding to the volume including the second flow path part B and the flow path upstream of the second flow path part B flows, the control unit 40 The energization permission to the flow sensor 42 is determined. In the present embodiment, the flow path shape and the cross-sectional area relating to the first flow path part A and the second flow path part B correspond to each other. The flow rate of air flowing through the flow path portion B can be estimated uniquely. However, even if the flow channel shape and the cross-sectional area relating to the first flow channel part A and the second flow channel part B are different, the flow rate ratio per unit time is obtained in advance. The flow rate of air flowing through the second flow path portion B can be identified from the detection value of the first flow sensor 41.

  If an affirmative determination is made in step 7, the second flow sensor 42 is energized and then the process proceeds to step 8 (S8). On the other hand, if a negative determination is made in step 7, the process of step 7 is executed again after a predetermined time.

  In step 8, it is determined whether or not the rotational speed of the compressor 30 has decreased and has reached the second rotational speed determination value Rth2. If the determination in step 8 is affirmative, that is, if the rotation speed of the compressor 30 has reached the second rotation speed determination value Rth2, the process proceeds to step 9 (S9). On the other hand, if a negative determination is made in step 8, that is, if the rotation speed of the compressor 30 has not reached the second rotation speed determination value Rth2, the process of step 8 is executed again after a predetermined time.

  In step 9, position control of the opening / closing valve 24b is performed. Specifically, the control unit 40 monitors the rotation speed of the compressor 30 and operates the valve body of the on-off valve 24b to the second maximum operating position at the timing when the rotation speed reaches the first rotation speed determination value Rth1. Thus, the position of the valve body of the on-off valve 24b between the neutral position and the second maximum movable position is controlled according to the difference between the current rotation speed and the first rotation speed determination value Rth1.

  In step 10, it is determined whether or not the rotation speed of the compressor 30 has decreased and has reached the first rotation speed determination value Rth1. If an affirmative determination is made in step 10, that is, if the rotation speed of the compressor 30 has reached the first rotation speed determination value Rth1, the process proceeds to step 11 (S11). On the other hand, if a negative determination is made in step 10, that is, if the rotation speed of the compressor 30 has not reached the first rotation speed determination value Rth1, the process of step 9 is executed again after a predetermined time.

  In step 11, it is determined whether or not to stop the system. Based on this determination, it is determined whether the scene is a scene in which the system is completely stopped or an idle stop in which the power generation of the fuel cell stack 1 is temporarily stopped. If an affirmative determination is made in step 11, that is, if the scene is a scene for stopping the system, the process proceeds to step 12 (S12). On the other hand, if a negative determination is made in step 11, that is, if the scene is not a scene for stopping the system, the process returns to step 3.

  In step 12, position control of the opening / closing valve 24b is performed. Specifically, the control unit 40 controls the open / close valve 24b to the first maximum movable position. As a result, the second flow path part B is opened and the first flow path part A is blocked.

  In step 13, as a system stop process, a process of stopping the supply of the reaction gas, that is, hydrogen and oxygen, and turning off the energization of the first and second flow rate sensors 41 and 42 are performed.

  FIG. 6 is an explanatory diagram of the first and second rotation speed determination values Rth1 and Rth2. In the figure, a line L1 indicates the correspondence between the rotation speed of the compressor 30 and the noise level in a state where the on-off valve 24b is controlled to the neutral position. As can be seen from the line L1, when the on-off valve 24b is controlled to the neutral position, the noise level increases as the rotation speed of the compressor 30 increases, and then decreases after reaching a temporary peak and then increases again. Has a trend. On the other hand, the line L2 indicates the rotation speed and noise level of the compressor 30 in a state where the open / close valve 24b is controlled to the maximum movable position (a state where one flow path (for example, the first flow path portion A) is blocked). The correspondence is shown. As can be seen from the line L2, when the on-off valve 24b is controlled to the maximum movable position, the noise level monotonously increases as the number of rotations of the compressor 30 increases.

  Further, when the open / close valve 24b is controlled to the neutral position and when the open / close valve 24b is controlled to the maximum movable position, the noise level magnitude relationship is reversed on the basis of the predetermined rotational speed. Specifically, in the case where the rotation speed is smaller than the first rotation speed determination value Rth1, the noise level is relative when the open / close valve 24b is controlled to the neutral position than when the open / close valve 24b is controlled to the maximum movable position. Become bigger. On the other hand, in the case where the rotational speed is larger than the second rotational speed determination value Rth1, the noise level is relatively smaller when the on-off valve 24b is controlled to the neutral position than when the on-off valve 24b is controlled to the maximum movable position. .

  Here, the first rotational speed determination value Rth1 is a rotational speed at a timing at which each noise level corresponds when the rotational speed of the compressor 30 is increased, that is, can be regarded as substantially the same value. Thereby, when the rotation speed of the compressor 30 is increased, the noise level in the state where the second flow path portion B is closed by the on-off valve 24b is lower than the noise level in the state where the on-off valve 24b is in a neutral state. The on-off valve 24b can be switched to the neutral position. Therefore, the rotation speed of the compressor 30 can be increased while maintaining a low noise level. Further, the second rotational speed determination value Rth2 is the rotational speed at a timing at which each noise level corresponds when the rotational speed of the compressor 30 is lowered, that is, can be regarded as substantially the same value. Thus, when the rotational speed of the compressor 30 is lowered, the noise level in the state where the on-off valve 24b is in the neutral position is lower than the noise level in the state where the second flow path portion B is closed by the on-off valve 24b. Thus, the on-off valve 24b can be closed. Thereby, the rotation speed of the compressor 30 can be lowered while maintaining a low noise level.

  Thus, in the fuel cell system of the present embodiment, the air flow path in the intake module 20 includes the first flow path portion A and the second flow path portion B that are independent from each other, and these flow path portions are merged. Later, it leads to the fuel cell stack 1. The air flow path is provided with an open / close valve 24b that can block either the first flow path portion A or the second flow path portion B. The first flow rate sensor that detects the flow rate of the air flowing through the flow path (first flow path portion A) in the energized state on the first flow path portion A upstream from the opening / closing valve 24b. 41 is provided on the upstream side of the open / close valve 24b and the second flow path portion B has a flow rate of air flowing through the flow path (second flow path portion B) in an energized state. A second flow sensor 42 for detection is provided.

  According to such a configuration, the first and second flow path portions A and B can be selectively blocked by the opening / closing valve 24b. Therefore, even if hydrogen diffuses from the fuel cell stack 1 side during the stop period, the first or second flow rate sensor 41, 42 in the flow path section A, B on the blocked side is transferred to. The amount of hydrogen that reaches is suppressed. Thereby, the situation where hydrogen exists in high concentration around the 1st flow sensor 41 can be controlled. As a result, it is possible to suppress a situation in which the flow rate sensors 41 and 42 are energized in a state where high-concentration hydrogen is present at the time of starting the system. Therefore, the safety at the time of starting can be improved. In particular, the configuration according to the present embodiment is optimal for a system that performs a stop process for replacing oxygen in the oxidizer electrode with hydrogen and an inert gas (for example, nitrogen) when the system is stopped from the viewpoint of suppressing deterioration of the fuel cell. It is.

  In the present embodiment, the first flow path part A and the second flow path part B extend the air flow path (specifically, the flow dividing unit 24) of the intake module 20 in the axial direction thereof. It is configured by dividing into two parallel spaces by a plate-like divided plate 24a. The on-off valve 24b is disposed at the end of the dividing plate 24a, and adjusts the opening area of the first flow path part A or the second flow path part B by operating the valve body. According to this configuration, the above-described effects can be realized with a simple configuration.

  In the present embodiment, the air flow path (specifically, the flow dividing unit 24) of the intake module 20 is provided with a turbulent flow suppressing device 24c that suppresses turbulent flow generated downstream of the on-off valve 24b. . According to this configuration, it is possible to suppress turbulent flow that occurs when the valve body of the on-off valve 24b is operated from the maximum movable position to the neutral position. Thereby, the noise by the intake module 20 can be reduced.

  In the present embodiment, the control unit 40 controls the open / close valve 24b and the energization states of the first and second flow rate sensors 41 and 42. The control unit 40 blocks the first flow path unit A when the system is stopped. Then, the control unit 40 performs a first process of blocking the second flow path part B and opening the first flow path part A at the time of starting the system, and energizes only the first flow rate sensor 41. .

  According to such a configuration, even if hydrogen diffuses from the fuel cell stack 1 side during the stop period, the hydrogen does not enter the atmosphere around the first flow sensor 41, so the first flow sensor It is possible to suppress a situation in which hydrogen is present at a high concentration around 41. Thereby, at the time of starting the system, it is possible to suppress a situation in which the first flow sensor 41 is energized in the presence of high-concentration hydrogen around the system. Thereby, the safety | security at the time of starting can be improved.

  In addition, the present embodiment further includes a compressor 30 that supplies an amount of air corresponding to the drive amount (rotation speed). The control unit 40 continues the first process after the system is started until the rotation speed of the compressor 30 reaches a first rotation speed determination value (first drive amount determination value) Rth1 set in advance. Do. When the compressor 30 intermittently sucks air, noise due to a pulsation phenomenon is generated upstream of the compressor 30. In particular, in a situation where the compressor 30 is low in rotation and the half-wavelength of the pressure pulsation tends to be an integral number of the flow path length in the intake module 20, resonance is likely to occur and low frequency noise is generated. Therefore, low frequency noise is generated in the intake module 20 installed upstream of the compressor 30. In this regard, according to the present embodiment, a part of the noise generated from the intake module 20 can be cut off, so that the intake noise can be reduced.

  Further, in the present embodiment, the control unit 40 sets the second rotation speed determination value (second drive amount determination value) in which the rotation speed of the compressor 30 is set to a value larger than the first rotation speed determination value Rth1. ) When larger than Rth2, the on-off valve 24b is controlled to the neutral position, and the second channel portion B is opened in the same manner as the first channel portion A. Generally, when the air flow rate is high, that is, when the rotation speed of the compressor 30 is high, turbulent flow is likely to occur. In a state where the opening of the flow path is restricted by the valve body of the opening / closing valve 24b, when the fluid passes through the opening / closing valve 24b at a high flow rate, a turbulent flow is more likely to occur due to the entrainment effect. become. When turbulent flow occurs, noise is generated due to air pressure turbulence. In this regard, according to the present embodiment, the noise caused by resonance is reduced by blocking the second flow path portion B in the low rotation range, and the on-off valve 24b is moved to the neutral position in the high rotation range. Control can reduce noise caused by turbulent flow. Moreover, since the pressure loss in the intake portion can be reduced by opening the second flow path portion B, the power consumption of the compressor 30 can be reduced.

  Further, in the present embodiment, the control unit 40, based on the detection result of the first flow sensor 41, the air that has flowed through the second flow path part B with reference to the timing at which the second flow path part B is opened. And the energization permission of the second flow sensor 42 is determined based on the estimation result. According to such a configuration, it is possible to control the second flow rate sensor 42 so as not to energize until a predetermined flow rate flows after the second flow path portion B is opened. For this reason, it is possible to energize the second flow rate sensor 42 while scavenging hydrogen in the second flow path portion B and the flow path on the upstream side thereof. Thereby, at the time of starting the system, it is possible to suppress a situation in which the first flow sensor 41 is energized in the presence of high-concentration hydrogen around the system.

  In the present embodiment, the control unit 40 flows the oxidant gas in an amount corresponding to the volume including the second flow path part B and the oxidant gas flow path upstream of the second flow path part B. If it is, the permission of energization to the second flow rate detection means is determined. According to such a configuration, it is possible to determine an appropriate flow rate for scavenging hydrogen in the second flow path portion B and the flow path on the upstream side thereof, so that the start-up time can be shortened.

  In the present embodiment, when the rotational speed of the compressor 30 tends to increase, the control unit 40 shuts off the second flow path section B after the rotational speed reaches the first rotational speed determination value Rth1. The release is started, and the opening of the second flow path part B is completed at a timing when the second rotational speed determination value Rth2 is reached. Alternatively, when the rotation speed of the compressor 30 tends to decrease, the control unit 40 starts blocking the second flow path section B after the rotation speed reaches the second rotation speed determination value Rth2. Thus, the blocking of the second flow path part B is completed at the timing when the first rotational speed determination value Rth1 is reached.

  According to this configuration, the open / close valve 24b can be switched in a state where the noise level in the state where the second flow path portion B is closed is equivalent to the noise level in the state where the open / close valve 24b is in the neutral position. Therefore, switching of the on-off valve 24b can be performed without deteriorating the noise level.

  Although the fuel cell system and the control method thereof according to the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the invention.

The block diagram which shows the whole structure of the fuel cell system concerning embodiment Explanatory drawing which shows the structure of the intake module 20 typically. Schematic diagram showing the configuration of the diversion unit 24 from above Explanatory drawing which shows typically operation | movement of the on-off valve 24b. 1 is a flowchart showing a procedure of a control method for a fuel cell system according to an embodiment. Explanatory diagram of first and second rotational speed determination values Rth1, Rth2

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel cell stack 2 Electric power take-out device 3 Electric motor 10 Fuel tank 11 Hydrogen pressure regulation valve 12 Hydrogen circulation pump 13 Purge valve 14 Hydrogen combustor 20 Intake module 21 Intake duct 22 Resonator 23 Filter 24 Dividing unit 24a Dividing plate 24b Figure opening / closing valve 24b Open / close valve 24c Turbulence suppression device 25 Silencer 30 Compressor 31 Air pressure regulating valve 40 Control unit 41 First flow sensor 42 Second flow sensor

Claims (14)

In the fuel cell system,
A fuel cell that generates electricity by electrochemically reacting a fuel gas supplied to the fuel electrode and an oxidant gas supplied to the oxidant electrode; and
A first flow path section and a second flow path section that are independent from each other, the first flow path section and the second flow path section are joined together and communicated with the fuel cell; An oxidant gas flow path for supplying an oxidant gas to the electrode;
A blocking means capable of blocking any one of the first channel portion and the second channel portion;
A first flow rate detection means that is provided upstream of the blocking means and provided in the first flow path portion, and that detects a flow rate of the oxidant gas flowing through the flow path in an energized state;
And a second flow rate detection means that is provided upstream of the blocking means and provided in the second flow path portion, and that detects the flow rate of the oxidant gas flowing through the flow path in the energized state. A fuel cell system. The first flow path section and the second flow path section are configured by dividing the oxidant gas flow path into two parallel spaces by a plate-shaped dividing plate extending in the axial direction,
The blocking means is disposed at the end of the dividing plate, and operates the semicircular valve body corresponding to the cross-sectional shape of the flow path to thereby operate the first flow path section or the second flow path. The fuel cell system according to claim 1, comprising an open / close valve that adjusts an opening area of the portion.   3. The fuel cell system according to claim 2, further comprising turbulent flow suppression means provided in the oxidant gas flow path and configured to suppress turbulent flow generated downstream of the opening / closing valve.   4. The apparatus according to claim 1, further comprising a control unit configured to control the blocking unit and to control an energization state of the first flow rate detection unit and the second flow rate detection unit. 5. The described fuel cell system.   5. The fuel cell system according to claim 4, wherein the control means shuts off the first flow path when the system is stopped.   The control means performs a first process of shutting off the second flow path portion and opening the first flow path portion at the time of starting the system, and energizing only the first flow rate detection means. The fuel cell system according to claim 5. Provided in the oxidant gas flow path, further comprising an oxidant gas supply means for supplying an oxidant gas in an amount corresponding to the drive amount;
The control unit continuously performs the first process after the system is started until the driving amount of the oxidant gas supply unit reaches a preset first driving amount determination value. The fuel cell system according to claim 6.   When the driving amount of the oxidant gas supply unit is larger than a second driving amount determination value set to a value larger than the first driving amount determination value, the control unit turns the blocking unit off. 8. The fuel cell system according to claim 7, wherein the second flow path part is opened together with the first flow path part by controlling to a neutral position.   The control unit estimates the flow rate of the oxidant gas that has flowed through the second flow path unit based on the detection result of the first flow rate detection unit with reference to the timing at which the second flow path unit is opened. The fuel cell system according to claim 8, wherein energization permission of the second flow rate detection means is determined based on the estimation result.   When the amount of oxidant gas corresponding to the volume including the second flow path portion and the oxidant gas flow path upstream of the second flow path portion flows, the control means The fuel cell system according to claim 9, wherein permission to energize the flow rate detecting means is determined.   When the driving amount of the oxidant gas supply unit is increasing, the control unit is configured to increase the second flow path after the driving amount of the oxidant gas supply unit reaches the first driving amount determination value. The release of the second flow path portion is completed at the timing when the release of the block is started and the second drive amount determination value is reached, or the drive amount of the oxidant gas supply means tends to decrease In some cases, after the driving amount of the oxidant gas supply means reaches the second driving amount determination value, the second flow path section starts to be shut off, and the first driving amount determination value is obtained. The fuel cell system according to any one of claims 8 to 10, wherein the second flow path section is completely shut off at a timing of reaching the position.   The first drive amount determination value includes a case in which only the first flow path portion is opened and the second flow path portion is blocked, and the first flow path portion and the second flow path portion. The fuel cell system according to claim 7, wherein the driving amount of the oxidant gas supply means is increased in the case where both of them are opened, and the respective noise levels are set to the rotational speeds at corresponding timings.   The second drive amount determination value includes a case in which only the first flow path portion is opened and the second flow path portion is blocked, and the first flow path portion and the second flow path portion. 9. The fuel cell system according to claim 8, wherein the driving amount of the oxidant gas supply means is reduced in each of the cases where both of them are opened, and the respective noise levels are set to the rotational speeds corresponding to each other. In a control method of a fuel cell system including a fuel cell that generates electricity by electrochemically reacting a fuel gas supplied to a fuel electrode and an oxidant gas supplied to an oxidant electrode,
A first flow path section and a second flow path section that are independent from each other, the first flow path section and the second flow path section are joined together and communicated with the fuel cell; Supplying an oxidant gas to the electrode;
Blocking any one of the first flow path part and the second flow path part by a blocking means;
Detecting a flow rate of the oxidant gas flowing through the first flow path portion by a first flow rate detection unit provided upstream of the blocking unit;
And a step of detecting the flow rate of the oxidant gas flowing through the second flow path section by a second flow rate detection means provided upstream of the blocking means. .

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