JP4876533B2 - Fuel cell stack and control method thereof - Google Patents

Description

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

  As shown in FIG. 15, the fuel cell stack 1 includes a stacked body 2 and a housing 3 that houses the stacked body 2. In the housing 3, an oxidizing gas supply port 3 a for supplying an oxidizing gas such as air to the stacked body 2 and a fuel supply port 3 b for supplying a fuel such as hydrogen to the stacked body 2 are formed.

  As shown in FIG. 16, the stacked body 2 is formed by stacking a plurality of cells 10. Each cell 10 includes a separator 12, a membrane electrode assembly (MEA) 11, and a separator 12, and adjacent cells 10 share a separator 12. Each membrane electrode assembly 11 includes an electrolyte membrane 11a made of a solid polymer membrane such as Nafion (registered trademark, Nafion (manufactured by Dupon)), and a cathode that is joined to one surface of the electrolyte membrane 11a and supplied with an oxidizing gas. The electrode 11b has an anode 11c joined to the other surface of the electrolyte membrane 11a and supplied with fuel. Each separator 12 is stacked with each membrane electrode assembly 11 interposed therebetween, and each separator forms an oxidizing gas flow path 12b on each cathode electrode 11b side and a fuel flow path 12c on each anode electrode 11c side. It is like that. The oxidizing gas supply port 3 a communicates with all the oxidizing gas flow paths 12 b of each cell 10, and the fuel supply port 3 b communicates with all the fuel flow paths 12 c of each cell 10.

  As illustrated in FIG. 15, the stacked body 2 may be a stack of a plurality of modules 20 including a plurality of cells 10. In this case, the fuel supplied from the fuel supply port 3b sequentially flows in units of 20 modules.

  In the fuel cell stack 1, moisture generated by a chemical reaction remains as water droplets in the oxidizing gas flow path 12 b in the stacked body 2. The water droplets are usually removed by being moved and discharged by the flow of the oxidizing gas or being taken away as water vapor by the oxidizing gas.

  However, when the flow rate or flow rate of the oxidizing gas is small, water droplets continue to remain in the oxidizing gas flow path 12b, which hinders the flow of the oxidizing gas and reduces the power generation efficiency. Specifically, when water droplets remain in the oxidizing gas flow channel 12b, the oxidizing gas flow channel 12b is closed, and power generation cannot be performed because the oxidizing gas does not flow there, and the portion where the water droplets are attached is closed. In some cases, the oxidant gas will not reach, and the effective power generation area will decrease.

  On the other hand, the oxidizing gas is introduced into the oxidizing gas supply port 3a of the laminate 2 by a blower, a pump, or the like. In order to remove the water droplets, the flow rate of the oxidizing gas in the oxidizing gas channel 12b must be increased. Some increase the discharge amount of a blower, a pump, etc. to such an extent that the water droplets can be removed. However, in that case, the generated power is consumed, which is not efficient.

  In this regard, Patent Document 1 discloses a fuel cell stack in which a slit is provided in the oxidizing gas passage 12b on the outlet side of the laminate 2 and the width of the slit can be adjusted. In patent document 1, the control method which changes the opening area of the exit of the oxidizing gas flow path 12b by this is employ | adopted. In this case, it is considered that an oxidizing gas having a high flow velocity is introduced into the oxidizing gas channel 12b, and water droplets are blown off to restore power generation efficiency.

JP 2005-5247 A

  However, in the fuel cell stack and its control method disclosed in the above patent document, a slit must be provided for each narrow oxidizing gas flow path, and it is necessary to precisely align the slit. Further, since the oxidizing gas channel must be opened and closed accurately by the slit, the working accuracy of the slit with respect to the position of the oxidizing gas channel must also be increased.

  The present invention has been made in view of the above-described conventional situation, and enables water droplets accumulated in the oxidizing gas flow path of the fuel cell stack to be removed without complicating the fuel cell system. This is a problem to be solved.

  A fuel cell stack according to a first aspect of the present invention includes a stacked body in which a plurality of cells are stacked, and a housing in which the stacked body is accommodated and an oxidizing gas supply port for supplying oxidizing gas to the stacked body is formed. In the fuel cell stack provided,

  The oxidant gas supply port can be formed with an opening that opens to the stacked body, the opening area of the opening can be changed, and the position of the opening with respect to the stacked body can be changed. Is provided.

  In the fuel cell stack of the first invention, a shutter is provided at the oxidizing gas supply port. The shutter can form an opening that opens to the stacked body, and the opening area of the opening can be changed and the position of the opening with respect to the stacked body can be changed. For this reason, when it is desired to remove water droplets in a part of the laminated body, an opening having a small opening area is opened to the part, and an oxidizing gas having a high flow velocity is introduced therein. In this way, the power generation efficiency can be recovered by blowing off water droplets.

  At this time, in this fuel cell stack, an opening is not provided for each narrow oxidizing gas flow path, and therefore, not much precision is required for alignment of the opening. In addition, since the oxidant gas flow can be introduced while allowing a larger width than the oxidant gas flow path, the accuracy for forming the opening is not necessary.

  Therefore, the fuel cell stack of the first invention can remove water droplets accumulated in the oxidizing gas flow path without complicating the fuel cell system. For this reason, according to this fuel cell stack, the fuel cell system is low-cost and can exhibit high durability.

  Specifically, the shutter is connected to one end of the non-breathable first screen having a strip shape extending in the stacking direction of the cells and one end of the first screen having a strip shape extending in the stacking direction. A second screen forming a portion, a first winding mechanism capable of winding up the second screen by driving from one end thereof, and a non-breathable gas connected to the first winding mechanism in a strip shape extending in the stacking direction A third screen, a second winding mechanism provided on one side of the laminate that is one of the lamination directions, and capable of winding up the third screen by driving from one end thereof; and provided on the other side of the laminate. And a winding mechanism capable of winding the first screen from the other end by a biasing force.

  The first screen and the third screen need only be impermeable, and may be made of, for example, vinyl.

  The second screen only needs to form an opening through which the oxidizing gas passes. For example, it is possible to employ a second screen in which connecting portions that connect the first screen and the first winding mechanism are formed at both ends in the width direction and the connecting portions are open. Also, a breathable mesh material can be used as the second screen.

  A stepping motor with a clutch or the like can be used as a drive source for the first winding mechanism and the second winding mechanism.

  For the winding mechanism, a stepping motor with a clutch or the like may be used, but it is preferable to employ a mechanism that uses a return force by elasticity of a spring, rubber or the like as an urging force. This simplifies the structure of the shutter and increases the effects of cost reduction.

  According to a second aspect of the present invention, there is provided a method of controlling a fuel cell stack comprising: a stacked body in which a plurality of cells are stacked; and an oxidizing gas supply port for containing the stacked body and supplying an oxidizing gas to the stacked body A control method for a fuel cell stack comprising a housing and a shutter provided at the oxidizing gas supply port and capable of forming an opening that opens to the stack,

  When the laminated body is in a performance-decreasing state, a water droplet removing operation step is provided which reduces the opening area of the opening and moves the opening uniformly with respect to the laminated body.

  If water droplets remain in the oxidant gas flow path of the laminate, the oxidant gas will not flow there, and power generation will not be possible, or the effective power generation area will be reduced, resulting in a degraded performance of the laminate. At this time, in the control method of the second invention, in the water droplet removing operation step, the opening area of the opening is reduced and the opening is moved uniformly with respect to the laminate. As a result, an oxidant gas flow having a high flow rate is sequentially introduced into all the oxidant gas flow paths in the laminate. In this way, the power generation efficiency can be recovered by blowing water droplets in all the oxidizing gas flow paths of the laminate. Moreover, since the performance degradation state for every cell is not judged, the fuel cell system is not complicated.

  In the control method of the second invention, the voltage and current values of the laminated body are detected, and a detection step of acquiring the detected value is compared with the reference IV, so that the laminated body is in the reduced performance state. It is preferable to include a comparison and determination step for determining whether or not there is. In this case, it can be reliably determined whether or not the laminated body is in a performance degraded state.

  Further, the control method of the second invention includes a recording step of performing recording on the recording means when the number of times that the laminated body is continuously determined to be in the performance degradation state exceeds a reference number. Is preferred.

  During the water droplet removal operation step, the oxidant gas is not supplied to the oxidant gas flow path in the portion other than the opening portion of the laminate, and the power generation capacity is reduced. For this reason, it is also important to maintain the power generation capacity without performing the water droplet removal operation step more than necessary by setting the criterion for determining the performance degradation state due to water clogging. Further, it is possible to record the deterioration of the laminated body that is not recovered in the water droplet removing operation step, and to improve the efficiency of the maintenance work.

  In the control method of the second invention, when the fuel cell stack is mounted on a vehicle, it is preferable that the water droplet removing operation step is executed when the vehicle is stopped in the medium term.

  When the vehicle is stopped in the medium term, it means that the drive position is N (neutral) or P (parking), the vehicle is stopped by pulling the parking brake, etc. It does not include the case where it is stopped. The case where the vehicle is stopped by stopping the power generation of the fuel cell system is not included. This is because the control method of the second invention requires a certain amount of time because the opening is moved uniformly with respect to the stacked body in the water droplet removing operation step.

  In the control method of the second invention, when the fuel cell stack is mounted on a vehicle, it is preferable to execute the water droplet removing operation step before the vehicle is stopped for a long time.

  The case where the vehicle is stopped for a long period refers to the case where the vehicle is stopped by stopping the power generation of the fuel cell system. Thereby, since a laminated body removes a water droplet from all the oxidation gas flow paths, and stops, the freezing when the next starting environmental temperature is below freezing point can be prevented, and starting can be made easy.

  According to a third aspect of the present invention, there is provided a method for controlling a fuel cell stack comprising: a stacked body in which a plurality of cells are stacked; and an oxidizing gas supply port for containing the stacked body and supplying an oxidizing gas to the stacked body. A control method for a fuel cell stack comprising a housing and a shutter provided at the oxidizing gas supply port and capable of forming an opening that opens to the stack,

  The laminated body is obtained by laminating a plurality of modules composed of a plurality of the cells, and when the specific cell or the specific module is in a degraded state, the opening area of the opening is reduced to reduce the opening. A water droplet removal operation step for positioning the specific module with the specific cell or the specific module.

  When the laminate is a laminate of a plurality of modules, the performance degradation state also occurs in cell units or module units. Therefore, in the control method of the third invention, if a specific cell or a specific module is in a degraded state, the opening area of the opening is reduced and the opening has the specific cell in the water drop removing operation step. Located for a specific module or for that specific module. As a result, the specific module introduces an oxidizing gas flow having a high flow rate into the oxidizing gas flow path. Thus, water drops can be blown off in the oxidizing gas flow path of the specific module, and the power generation efficiency can be recovered in a short time. In addition, the fuel cell system is not complicated because it does not determine the performance degradation state for each cell and does not execute the water droplet removal operation step for each cell.

  A control method according to a third aspect of the invention includes a detection step of detecting a voltage of each cell and a current value of the stacked body, and obtaining a detection value for each cell or each module, and comparing each detection value with a reference IV It is preferable to include a comparison and determination step for determining which of the modules is in a degraded state. In this case, it is possible to reliably determine which module is in a degraded performance state.

  In the comparison and determination step, it is preferable to rank the modules in descending order of performance degradation. This is because it is possible to identify a module that should be promptly restored and effectively restore the power generation capacity.

  The control method according to the third aspect of the invention is a recording method for performing recording in a recording means when the number of times that the specific cell or the specific module is continuously judged to be in the performance-decreasing state exceeds a reference number. It is preferable to include a step.

  In this case, by setting a criterion for determining the state of performance degradation due to water clogging, the power generation capacity can be maintained without performing the water droplet removal operation step more than necessary. In addition, it is possible to easily identify a deteriorated cell or module that is not recovered in the water droplet removal operation step, thereby improving the efficiency of maintenance work.

  In the control method of the third invention, it is preferable that when the fuel cell stack is mounted on a vehicle, the water droplet removing operation step is executed when the vehicle is stopped for a short time.

  The case where the vehicle is stopped for a short term refers to the case where the vehicle is stopped by a foot brake. When the drive position is N (neutral) or P (parking), the vehicle is stopped by pulling the parking brake, or the vehicle is stopped by stopping the power generation of the fuel cell system. It is not included. This is because the control method according to the third aspect of the invention requires only a short time since the opening is moved only with respect to a specific module in the water droplet removal operation step.

  Hereinafter, Embodiments 1 and 2 embodying the first to third aspects of the invention will be described with reference to the drawings. The first embodiment embodies the first and second inventions, and the second embodiment embodies the first and third inventions.

  FIG. 1 shows a schematic configuration diagram of a vehicle fuel cell system according to a first embodiment. In this fuel cell system, a plurality of cells 10 shown in FIG. Further, the plurality of modules 20 are further stacked to form a stacked body 2 shown in FIG.

  The fuel cell stack 1 includes the stacked body 2 and a housing 3 that houses the stacked body 2. The housing 3 is formed with an oxidizing gas supply port 3a for supplying air to the stacked body 2 from the upper surface, and a fuel supply port 3b for supplying fuel gas to the stacked body 2 from one of the side surfaces. As shown in FIG. 1, as a characteristic configuration of the first embodiment, the fuel cell stack 1 is provided with a shutter 30 at the oxidizing gas supply port 3a.

  A blower 51 is provided on the upstream side of the shutter 30. The air supplied from the oxidizing gas supply port 3a via the shutter 30 by the blower 51 flows to the lower surface of the stacked body 2 after passing through the oxidizing gas flow path 12b of each cell 10 shown in FIG.

  Further, as shown in FIG. 1, the fuel cell stack 1 is provided with a fuel supply device 52 upstream of the fuel supply port 3b. The fuel gas supplied from the fuel supply port 3 b by the fuel supply device 52 flows through the fuel flow path 12 c of each cell 10 for each module 10 and then flows to the other side surface of the stacked body 2.

  As shown in FIG. 2, the shutter 30 includes a first screen 31, a second screen 32, a first winding mechanism 33, a third screen 34, a second winding mechanism 35, and a winding mechanism 36. The second winding mechanism 35 and the winding mechanism 36 are fixed to the housing 3.

  The first screen 31 and the third screen 34 are non-breathable in the form of strips extending in the stacking direction of the cells 10 and the modules 20.

  The second screen 32 is connected to one end of the first screen 31 in a strip shape extending in the stacking direction, and connecting portions 32a for connecting the first screen 31 and the first winding mechanism 33 are formed at both ends in the width direction. Thus, an opening 32b is formed between the connecting portions 32a. The connecting portion 32a is made of a flexible material.

  The first hoisting mechanism 33 has a main unit (not shown) with a stepping motor with a clutch built therein. One end of the second screen 32 is fixed to a roll (not shown) driven by the stepping motor, and the second screen 32 can be wound up from the one end by driving the stepping motor. A third screen 34 is fixed to the main body of the first winding mechanism 33.

  The second winding mechanism 35 is provided with a main body (not shown) on one side of the laminated body 2 that is one side in the stacking direction, and a stepping motor with a clutch (not shown) is built in the main body. One end of the third screen 34 is fixed to a roll (not shown) driven by the stepping motor, and the third screen 34 can be wound up from the one end by driving the stepping motor.

  The winding mechanism 36 is provided with a main body on the other side of the laminate 2, and a roll having a biasing force by a spring (not shown) is built in the main body. The biasing force of the spring is opposite to the normal rotation direction of the stepping motors of the first and second winding mechanisms 33 and 35. The other end of the first screen 31 is fixed to this roll, and the first screen 31 can be wound from the other end by a biasing force.

  As shown in FIG. 1, the shutter 30 is connected to a controller 53. The controller 53 is also connected to a blower 51, a fuel supply device 52, a diagram 54 as a recording means, a display device 55, and a state sensor 56. The controller 53 stores these control programs.

  In the initial state, as shown in FIG. 4, the opening 32 b of the shutter 30 is open to the stacked body 2.

  The controller 53 performs processing according to the flowchart shown in FIG. This flowchart is executed when a relatively long stop is expected during normal operation.

  First, when the program starts after the vehicle is started, a water droplet removal operation counter “CA” is initialized to 0 in step S10.

  In step S11, normal operation processing of the fuel cell stack 1 is performed. During this time, in step S12 (detection step), the stack voltage and current value at various loads during operation are recorded.

  In step S13, based on the input from the state sensor 56, it is determined whether or not the vehicle speed is 0 and the drive position is N (neutral) or P (parking). This is because a relatively long stop is expected in this state.

  If YES in step S13, in step S14 (comparison determination step), the output current-voltage relationship recorded in step S12 is compared with the pre-stored reference output current-voltage relationship.

  In step S15 (comparison determination step), if the result of the comparison in step S14 shows that a performance deterioration of a certain level or more is recognized, the process proceeds to YES. Otherwise, the process proceeds to step S16, the water droplet removal operation number counter “CA” is cleared to 0, and the process returns to step S11.

  If YES in step S15, it is confirmed in step S17 that the water droplet removal operation number counter “CA” is less than 5, for example. This is for recording an abnormality when no effect is seen even if the water droplet removing operation step is performed a predetermined number of times or more.

  Therefore, if NO in step S17, the process proceeds to step S18 (recording step), and the abnormality is recorded in the diagram 54. Further, since it is considered that the performance has deteriorated, the process proceeds to step S19, and the display device 55 such as an indicator lamp is turned on to notify the driver. Then, the process proceeds to step S20, and the performance drop determination is not performed, and the same water droplet removal operation step as step 21 described later is performed at regular time intervals. This is because water drops cannot be removed on the basis of performance degradation, but it is considered that water drops remain because power is being generated.

  If “YES” in the step S17, the process proceeds to a step S21 (water droplet removing operation step). This is because water drops remain in the oxidizing gas flow path 12b and the output is reduced.

  At this time, in the initial state, as shown in FIG. 4, since the opening 32b of the shutter 30 is opened with respect to the stacked body 2, first, the first winding mechanism 33 rotates when the clutch is turned on. As shown in FIG. 5, the second screen 32 is pulled out by a predetermined width. The width of the opening 32b at this time is determined in advance by conducting an experiment in advance.

  As shown in FIG. 6, the second winding mechanism 35 sends out the third screen 34 in accordance with the pulling force of the winding mechanism 36 and moves the opening 32 b at a constant speed. In this way, the opening 32b having a small opening area is uniformly moved with respect to the stacked body 2. The moving speed at this time is determined in advance by conducting an experiment in advance. Thereby, the laminated body 2 introduce | transduces sequentially the air flow with a large flow velocity into all the oxidizing gas flow paths 12b.

  As shown in FIG. 7, when the first screen 31 is almost caught in the winding mechanism 36, the clutch of the first winding mechanism 33 is turned off, and as shown in FIG. 8, the third screen 34 is moved by the second winding mechanism 35. Roll up.

  If there is a power generation start command from the controller 53 during the execution of step S21, the execution of step S21 is immediately stopped, the clutch of the first winding mechanism 33 is immediately turned off, and the second winding mechanism 35 is immediately turned off. Thus, the third screen 34 is wound up and returned to the initial state.

  When the winding of the third screen 34 by the second winding mechanism 35 is completed, the initial state shown in FIG. 4 is restored. Then, in step 22 shown in FIG. 3, the water drop removal operation number counter “CA” is incremented to record the water drop removal operation history, and the process returns to step S11. However, if there is a power generation start command from the controller 53 during the execution of a series of steps S21, the third screen 34 is quickly rolled up and normal operation is started, so if step S21 is not completed, This recording is not performed.

  As a result of the execution of the above step S21, the stacked body 2 results in the oxidant gas flow path 12b being throttled, and the flow velocity in the oxidant gas flow path 12b is sequentially increased. Performance degradation due to clogging is restored. Note that the rotational speed of the blower 51 during the water droplet removal operation is determined in advance so as to avoid consuming power more than necessary by conducting an experiment in advance.

  The controller 53 also performs processing according to, for example, the flowchart shown in FIG. This flowchart is executed when the fuel cell system is not generating power. This flowchart is also executed before the fuel cell system is completely stopped to facilitate starting when the next start-up is in an environment below freezing.

  First, when the program starts, following step S11 in which the fuel cell stack 1 is generating power, in step S30, it is determined whether or not the controller 53 has sent a signal for stopping the operation of the fuel cell stack 1. When the stop operation of the fuel cell stack 1 is not started, the normal operation is continued.

  If YES in step S30, step S21 is activated. In step S31, the fuel cell stack 1 performs a series of stop operations to stop operation.

  Thereby, since the laminated body 2 is stopped by removing water droplets from all the oxidizing gas flow paths 12b, freezing when the next startup environment temperature is below freezing point can be prevented, and start-up can be facilitated.

  In the meantime, in the fuel cell stack 1, since the opening 32b is not provided for each narrow oxidizing gas flow path 12b, the positioning of the opening 32b does not require much precision. In addition, since air can be introduced while allowing a larger width than the oxidizing gas flow path 12b, the accuracy for forming the opening 32b is not so much required.

  Therefore, the fuel cell stack 1 can remove water droplets accumulated in the oxidizing gas flow path 12b without complicating the fuel cell system. For this reason, according to this fuel cell stack 1, the fuel cell system can maintain the cell performance at a high performance, is low in cost, and can exhibit high durability.

  In the fuel cell system according to the second embodiment, when a performance drop due to water clogging occurs in a specific module 20, the air flow is concentrated only in the vicinity of the module 20 to complete the processing in a short time and restore the performance. To resume driving. This fuel cell system can recover its performance at an early stage by, for example, performing this during a short time such as waiting for a signal while traveling.

  The basic configuration of the fuel cell system is the same as that of the first embodiment. However, the output voltage of each cell 10 is individually monitored. Thereby, it can be detected that the performance degradation due to water clogging has occurred in the specific cell 10 or module 20.

  For example, the controller 53 performs processing according to the flowchart shown in FIG. This flowchart is executed when a relatively short stop is expected during normal operation, such as waiting for a signal.

  First, when the program starts after the vehicle is started, a water droplet removal operation counter “CB (n)” is initialized to 0 in step S40. The water droplet removal operation number counter “CB (n)” has a separate recording area for each fuel cell stack 1 (may be for each cell 10), and the entire area is initialized to zero.

  In step S41, the module 20 whose power generation performance does not recover even when the water droplet removal operation step is performed a plurality of times is excluded from the target of the water droplet removal operation step. For this reason, an identification flag of FB (n) = false is set and initialized for all areas at the start.

  In step S42, normal operation processing of the fuel cell stack 1 is performed. Meanwhile, in step S43 (detection step), the cell voltage and the stack current value at various loads during operation are recorded.

  In step S44, based on the input from the state sensor 56, it is determined whether or not the vehicle speed has become zero. In this state, the vehicle is stopped by the foot brake, and a relatively short stop is expected.

  If YES in step S44, in step S45 (comparison judgment step), the output current-voltage relationship for each module 20 recorded in step S43 is compared with the pre-stored reference output current-voltage relationship. . In addition, you may compare for every cell 10. FIG.

  In step S46 (comparison judgment step), as a result of the comparison in step S45, the module 20 is ranked in the order of significant performance degradation.

  In step S47 (comparison judgment step), in order to speed up the processing, the module 20 (m) whose performance has been degraded the most is targeted for the water droplet removal operation.

  In step S48 (comparison judgment step), the identified module 20 (m) is checked for the presence or absence of an identification flag of FB (m) = false, and this module 20 (m) has no effect on water drop removal in the past. As to whether it is excluded from the target.

  In step S49 (comparison judgment step), the module 20 (m) excluded from the target is removed from the ranking, and the process returns to step S47 to recalculate.

  In step S50 (comparison determination step), if the module 20 (m) is compared in step S45 and a performance decrease of a certain level or more is recognized, the process proceeds to YES. Otherwise, the process proceeds to step S51, where the water droplet removal operation number counter “CB (n)” is cleared to 0, and the process returns to step S42.

  If YES in step S50, it is confirmed in step S52 that the water droplet removal operation number counter “CB (n)” is less than 5, for example. This is for recording an abnormality when no effect is seen even if the water droplet removing operation step is performed a predetermined number of times or more.

  For this reason, if “NO” in the step S52, the process proceeds to a step S53 to set an identification flag of FB (m) = true. Then, the process proceeds to step S54 (recording step), and the abnormality is recorded in the diagram 54. Then, the process proceeds to step S42.

  If “YES” in the step S52, the process proceeds to a step S53 (water droplet removing operation step). This is because water drops remain in the oxidizing gas flow path 12b and the output is reduced.

  At this time, in the initial state, as shown in FIG. 4, since the opening 32b of the shutter 30 is opened with respect to the stacked body 2, first, the first winding mechanism 33 rotates when the clutch is turned on. 11, the second screen 32 is pulled out by a predetermined width, and at the same time, the second winding mechanism 35 sends out the third screen 34 according to the pulling force of the winding mechanism 36, and opens the opening 32 b at a high speed. Move to a specific module 20. The width of the opening 32b at this time is determined in advance by conducting an experiment in advance.

  When the opening 32b reaches the specific module 20, as shown in FIG. 12, the state is maintained for a predetermined time or until the start of power generation of the fuel cell stack 1, and water droplets are removed. As a result, the specific module 20 introduces an air flow having a high flow velocity into the oxidizing gas flow path 12b.

  After removing the water droplets, the clutch of the first winding mechanism 33 is turned off, and the third screen 34 is wound up by the second winding mechanism 35 as shown in FIG. The first screen 31 is wound up by the winding mechanism 36.

  If there is a power generation start command from the controller 53 during the execution of step S53, the execution of step S53 is immediately stopped, the clutch of the first winding mechanism 33 is immediately turned off, and the first winding mechanism 35 is immediately turned off. The first and third screens 31 and 34 are wound up by the winding mechanism 36 and returned to the initial state.

  When the winding of the first and third screens 31 and 34 by the first winding mechanism 35 and the winding mechanism 36 is completed, the initial state shown in FIG. 4 is restored. Then, in step S54 shown in FIG. 10, the water drop removal operation number counter “CB (m)” is incremented for each module 20 to record the water drop removal operation operation history, and the process returns to step S42. However, if there is a power generation start command from the controller 53 during the execution of a series of steps 53, the first and third screens 31 and 34 are immediately rolled up and normal operation is started, so step S53 is completed. If not, this recording is not performed.

  In this way, water droplets can be blown off in the oxidizing gas flow path 12b of the specific module 20, and the power generation efficiency can be recovered in a short time. Further, since the performance drop state for each cell 10 is determined and the water droplet removal operation step is not executed for each cell 10, the fuel cell system is not complicated. Note that the rotational speed of the blower 51 during the water droplet removal operation is determined in advance so as to avoid consuming power more than necessary by conducting an experiment in advance.

  In the following, the performance degradation determination logic common to the first and second embodiments will be described. For example, as shown in FIG. 14, a reference output current-voltage relationship is recorded in advance. This is a region in which, in each current density region, a case where the voltage drops below the solid line is regarded as water clogging. This is an experimentally determined value.

  The voltage (V) of the Y axis is different between the case where the laminate 2 is evaluated and the case where the module 20 is evaluated. Actually, different output current-voltage relationships are recorded for the evaluation of the laminate 2 or for the evaluation of the module 20, but since both have the same shape, FIG. The diagram is shown. The hatched portion is the performance degradation region.

  In the vehicle, the fuel cell stack 1 is operated with various loads, but the voltage and current value are measured at a constant timing. If these are measured every second, 100 measurement points are collected in 100 seconds. When the total number of measurement points is 50 points or more and 80% of these points enter the performance deterioration region, it is preferable to determine that “the performance deterioration is a certain level or more”. If the measurement point data exceeds 100 points, the latest data is adopted and the oldest data is deleted.

As for data to be measured, it is preferable not to use data in the vicinity of OCV (open potential). It is preferable to use data only when the current density is 0.1 A / cm ² or more. This is because OCV is not easily affected by oxygen supply inhibition by water droplets. When the water droplet removal operation is completed, the measurement point is erased and a new measurement is started. The above numerical values are merely examples, and the present invention is not limited to these.

  In the above, the present invention has been described with reference to the first and second embodiments. However, the present invention is not limited to the first and second embodiments, and can be appropriately modified and applied without departing from the spirit of the present invention. Needless to say.

  The present invention is applicable to a fuel cell system, particularly a vehicle fuel cell system.

1 is a schematic configuration diagram of a vehicle fuel cell system according to Embodiments 1 and 2. FIG. 1 is a plan view of a fuel cell stack according to Examples 1 and 2. FIG. 3 is a flowchart of a controller according to the first embodiment. 1 is a plan view of a fuel cell stack according to Examples 1 and 2. FIG. 1 is a plan view of a fuel cell stack according to Example 1. FIG. 1 is a plan view of a fuel cell stack according to Example 1. FIG. 1 is a plan view of a fuel cell stack according to Example 1. FIG. 1 is a plan view of a fuel cell stack according to Example 1. FIG. 3 is a flowchart of a controller according to the first embodiment. 6 is a flowchart of a controller according to a second embodiment. 6 is a plan view of a fuel cell stack according to Example 2. FIG. 6 is a plan view of a fuel cell stack according to Example 2. FIG. 6 is a plan view of a fuel cell stack according to Example 2. FIG. It is a graph of the output current-voltage relationship which concerns on Example 1, 2 and shows a performance fall area | region. It is a model perspective view of the conventional fuel cell stack. It is a schematic cross section of a cell, a module, and a laminated body.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Cell 2 ... Laminated body 3 ... Housing 3a ... Oxidizing gas supply port 1 ... Fuel cell stack 32b ... Opening 30 ... Shutter 31 ... First screen 32 ... Second screen 33 ... First winding mechanism 34 ... Third screen 35 ... second winding mechanism 36 ... winding mechanism S21, S53 ... water droplet removal operation step S12, S43 ... detection step S14, S15, S45-S50 ... comparison judgment step S18, S54 ... recording step

Claims (12)

In a fuel cell stack comprising a laminate in which a plurality of cells are laminated, and a housing in which the laminate is accommodated and an oxidizing gas supply port for supplying an oxidizing gas to the laminate is formed.
The oxidant gas supply port can be formed with an opening that opens to the stacked body, the opening area of the opening can be changed, and the position of the opening with respect to the stacked body can be changed. A fuel cell stack characterized in that is provided.   The shutter is connected to one end of the first screen having a strip shape extending in the stacking direction and a non-breathable first screen having a strip shape extending in the stacking direction of the cells, and forming the opening. Two screens, a first winding mechanism capable of winding up the second screen by driving from one end thereof, a non-breathable third screen connected to the first winding mechanism in a strip shape extending in the stacking direction, A second winding mechanism provided on one side of the laminate that is one of the lamination directions and capable of winding up the third screen by driving from one end thereof; and provided on the other side of the laminate, the first screen. The fuel cell stack according to claim 1, further comprising a winding mechanism capable of winding the battery from the other end by an urging force. A stacked body in which a plurality of cells are stacked; a housing in which the stacked body is accommodated and an oxidizing gas supply port for supplying an oxidizing gas to the stacked body is formed; and the oxidizing gas supply port, A control method of a fuel cell stack comprising a shutter capable of forming an opening that opens to the laminate,
A fuel comprising a water droplet removing operation step of reducing the opening area of the opening and moving the opening evenly with respect to the stack when the stacked body is in a degraded performance state Battery stack control method. A detection step of detecting a voltage and a current value of the laminate and obtaining a detection value;
The fuel cell stack control method according to claim 3, further comprising a comparison and determination step of determining whether or not the stacked body is in the performance degradation state by comparing the detected value with a reference IV.   5. The method of controlling a fuel cell stack according to claim 4, further comprising a recording step of performing recording on a recording means when the number of times that the laminated body is continuously determined to be in the performance degradation state exceeds a reference number. .   The control of the fuel cell stack according to any one of claims 3 to 5, wherein when the fuel cell stack is mounted on a vehicle, the water droplet removing operation step is executed when the vehicle is stopped in the medium term. Method.   6. The fuel cell stack according to claim 3, wherein when the fuel cell stack is mounted on a vehicle, the water droplet removing operation step is executed before the vehicle is stopped for a long period of time. Control method. A stacked body in which a plurality of cells are stacked; a housing in which the stacked body is accommodated and an oxidizing gas supply port for supplying an oxidizing gas to the stacked body is formed; and the oxidizing gas supply port, A control method of a fuel cell stack comprising a shutter capable of forming an opening that opens to the laminate,
The laminated body is obtained by laminating a plurality of modules composed of a plurality of the cells, and when the specific cell or the specific module is in a degraded state, the opening area of the opening is reduced to reduce the opening. A method for controlling a fuel cell stack, comprising: a water droplet removing operation step of positioning a specific module having the specific cell or a specific module with the specific cell. Detecting the voltage of each cell and the current value of the stack, and obtaining a detection value for each cell or for each module;
9. The method of controlling a fuel cell stack according to claim 8, further comprising a comparison and determination step of comparing each of the detected values with a reference IV and determining which of the modules is in a degraded state.   The fuel cell stack control method according to claim 9, wherein in the comparison and determination step, the module is ranked in descending order of performance degradation.   11. A recording step of performing recording in a recording unit when the number of times that the specific cell or the specific module is continuously determined to be in the degraded performance state exceeds a reference number. The fuel cell stack control method described.   The control of a fuel cell stack according to any one of claims 8 to 11, wherein when the fuel cell stack is mounted on a vehicle, the water droplet removing operation step is executed when the vehicle is stopped for a short time. Method.

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