JP4590965B2 - Current measuring device - Google Patents

Description

  The present invention relates to an apparatus for measuring a local current of a fuel cell including a cell that generates electric energy.

  2. Description of the Related Art Conventionally, a fuel cell that generates electric power by using an electrochemical reaction between hydrogen and oxygen is known as a power device including a cell that discharges electric energy. Then, the cell voltage is measured during operation of the fuel cell, and an abnormality during operation of the fuel cell is detected based on the measured value. In addition, the current-voltage characteristics of the fuel cell are also inspected at the manufacturing stage.

  However, the cause of abnormality during the operation of the fuel cell includes, for example, insufficient supply of oxygen, insufficient supply of hydrogen, and increased resistance of the electrolyte, all of which appear in the form of voltage drop. Therefore, only by measuring the voltage, it is not possible to specify the cause of abnormality during operation, and a problem arises that appropriate measures according to the factor cannot be performed.

  In addition, when the in-plane processing variation of the cell is large, the in-plane variation of the contact resistance is increased and the variation of the current density is increased. Such a cell with large processing variation has a higher deterioration rate because current concentrates in a partial region than a cell in an appropriate processing state. If there is a cell with a large processing variation in a part of the stacked cells, the cell becomes unable to generate power at an early stage, so that even if other cells are normal, operation as a battery stack becomes impossible. In addition, if stacking is performed by eliminating cells with large processing variations in advance, the life of the battery stack can be extended. However, in the current-voltage characteristic inspection at the manufacturing stage, processing variations may occur in some of the stacked cells. It was not possible to know whether there was a large cell.

  In view of the above points, the present invention makes it possible to identify a cause of abnormality in use of a fuel cell including a cell that generates electrical energy, or to detect a cell having a quality problem at the manufacturing stage. For the purpose.

  By the way, for example, when drying, excessive moisture, or insufficient supply of fuel gas occurs in a fuel cell, the local current in a portion in the cell that tends to dry, a portion that tends to be excessive in water, or a portion that tends to be short of fuel gas is significantly reduced. As described above, since the local current of a specific portion changes greatly according to the cause of the abnormality, it is possible to specify the cause of the abnormality during the operation of the fuel cell by measuring the local current. Further, by measuring the local current at the manufacturing stage, it becomes possible to detect a cell having a quality problem at the manufacturing stage.

  Therefore, the present invention aims to achieve the above object by making it possible to measure the local current of the fuel cell with a current measuring device.

The invention according to claim 1 is a current measuring device for measuring a current of a fuel cell (1) in which a plurality of cells (10) are stacked, the current measuring device being arranged between the stacked cells, Plate-like conductors (211, 221) through which current flows, columnar portions (2 2 13, 22 2 3) provided so as to be surrounded by the grooves (2 2 12, 22 2 2), and grooves And a magnetic sensor (212, 213, 223) for measuring the strength of the magnetic field generated around the columnar part, and a first electrode provided in contact with the surface of the conductor (221) provided with the columnar part. The columnar portion and the magnetic sensor correspond to at least one of a portion in the cell that tends to dry, a portion that tends to be excessive in water, or a portion that tends to be short of fuel gas. provided on the site The magnetic sensor is located in the space formed by the groove between the conductor and the second conductor, and measures the strength of the magnetic field generated around the columnar part when current flows through the columnar part. Then, the current flowing through the columnar part is measured by converting the measured magnetic field strength into a voltage .

  According to this, since the current of the local part in the cell flows through the columnar part and a magnetic field corresponding to the current flowing through the columnar part is generated around the columnar part, the current of the local part is generated based on the strength of the magnetic field. Can be measured. Therefore, by using this current measuring device, it is possible to identify a cause of abnormality in use of a fuel cell including a cell that emits electric energy, or to detect a cell having a quality problem at the manufacturing stage. It becomes possible.

  Moreover, since the current change at the time of occurrence of an abnormality appears earlier and more remarkably than the voltage change, the abnormality can be detected at an early stage by measuring the current.

  Further, since the magnetic sensor is housed in the groove, interference between the magnetic sensor and the cell can be avoided. Therefore, a conductor can be disposed between a plurality of stacked cells. For example, a current measuring device can be disposed at a location that is particularly easily dried inside the fuel cell.

  By the way, when the current measuring device is arranged between the cells, the current measuring device is sandwiched between the separators, and usually a groove-like cooling water flow path through which the cooling water flows is formed on the surface of these separators. At this time, in a configuration in which a groove or the like is in contact with the surface of the separator, it is necessary to design the cooling water flow path of the separator by bypassing them, and the degree of freedom in designing the cooling water flow path is reduced.

Therefore , the second conductor (222) provided so as to be in contact with the surface of the conductor (221) provided with the columnar portion is provided, and the magnetic sensor is provided by a groove between the conductor and the second conductor. By positioning it in the space to be formed, it is possible to prevent the grooves and columnar portions from being exposed. Thereby, the freedom degree of design of the cooling water flow path in the surface of a separator can be enlarged. Furthermore, by placing the iron core in the space formed between the two conductors, it is possible to prevent the iron core from being loaded and to prevent distortion. Thereby, it is possible to prevent the deterioration of the magnetic characteristics of the magnetic material due to the distortion.

As in the second aspect of the invention, an elastic body (226) having conductivity is provided between the conductor and the second conductor, so that the gap between the cell and the conductor can be reduced. The contact can be improved, and the contact resistance generated between them can be reduced.

The invention according to claim 3 is characterized in that the groove is provided with a buffer material (225) for fixing the magnetic sensor, and the groove and the magnetic sensor are insulated. . Thereby, it is possible to prevent the magnetic sensor from rattling inside the groove, and it is possible to prevent deterioration of the magnetic characteristics.

According to the fourth aspect of the present invention, even when the magnetic sensor is bonded and fixed in the groove, it is possible to prevent the magnetic sensor from rattling inside the groove and to prevent deterioration of the magnetic characteristics. .

As in the invention described in claim 5 , by providing an elastic body (12, 13) having conductivity between the cell and the conductor, the contact between the cell and the conductor can be improved. And the contact resistance generated between them can be reduced.

The invention according to claim 6 is a current measuring device for measuring the current of a fuel cell in which a plurality of cells (10) for generating electrical energy by an electrochemical reaction between an oxidant gas and a fuel gas are stacked, , At least one of the fuel gas flow path through which the fuel gas flows and the oxidant gas flow path through which the oxidant gas flows are disposed outside the electrolyte / electrode assembly (111) in which a pair of electrodes are disposed on both sides of the electrolyte membrane. In the separator, a columnar portion provided so as to be surrounded by the groove, and a magnet for measuring the strength of a magnetic field generated in the columnar portion. a sensor, a conductor second conductor columnar portion is provided in contact with the surface provided in (221) (222), the columnar portion and a magnetic sensor, contact the separator Te, easy to dry sites within the cell, and overhydration and prone sites or the fuel gas is provided in at least one site for site and easy insufficient, magnetic sensor, around the columnar portion by flowing a current in the columnar portion The current flowing in the columnar part is measured by measuring the strength of the magnetic field generated in the first and converting the measured strength of the magnetic field into a voltage .

  Accordingly, the same effect as that of the first aspect of the invention can be obtained. Further, since the conductive separator provided in the fuel cell is used, there is no need to newly provide a plate-like conductor.

  In addition, the code | symbol in the bracket | parenthesis of each said means shows the correspondence with the specific means as described in embodiment mentioned later.

(First embodiment)
A current measuring apparatus according to a first embodiment of the present invention will be described. FIG. 1 is a perspective view of a fuel cell 1 equipped with a current measuring device 20 according to the first embodiment, and FIG. 2 is a side view of the fuel cell 1 of FIG.

  The fuel cell 1 of this embodiment is a solid polymer electrolyte membrane fuel cell, in which a large number of cells 10 serving as basic units are stacked and electrically connected in series. As shown in FIG. 2, a cell 10 includes an MEA (Membrane Electrode Assembly) 100 in which electrodes are arranged on both sides of an electrolyte membrane, an air-side separator 110 and a hydrogen-side separator that sandwich the MEA 100. 120. Separator 110, 120 consists of a plate-like member made of a carbon material or a conductive metal.

  As shown in FIG. 1, the fuel cell 1 is supplied with air and hydrogen. As shown by a solid line in FIG. 2, an air flow path A for flowing air is formed in the air-side separator 110, and oxygen is supplied in parallel to each cell 10 through the air flow path A. The Further, as shown by a one-dot chain line in FIG. 2, the hydrogen separator 120 is formed with a hydrogen flow path B for flowing hydrogen, and hydrogen is parallel to each cell 10 via the hydrogen flow path B. To be supplied. Since the electrolyte membrane needs to be in a wet state, the air and hydrogen supplied to the fuel cell 1 are humidified by a humidifier (not shown).

  In the fuel cell 1, when hydrogen is supplied with oxygen, the following electrochemical reaction occurs and electric energy is generated.

(Negative electrode side) H ₂ → 2H ⁺ + 2e ⁻
(Positive electrode side) 2H ⁺ + 1 / 2O ₂ + 2e ⁻ → H ₂ O
As shown in FIG. 1, terminal plates 11 are arranged at both ends of the stacked cells 10. As indicated by diagonal lines in FIG. 1, a current measuring device 20 is disposed between two cells 10.

  3 is a perspective view of the current measuring device 20 of FIG. 1, FIG. 4 (a) is a front view of the plate portion 200 in the current measuring device 20 of FIG. 1, and FIG. 4 (b) is a right side view of the plate portion 200. 6C is a cross-sectional view taken along line AA in FIG. 4A, and FIG. 4D is a cross-sectional view taken along line BB in FIG. 6A. In the current measuring device 20 of the present embodiment, a plurality of current sensors 205 and the like are provided, but only one current sensor 205 and the like are illustrated in FIGS.

  As shown in FIGS. 3 and 4, the current measuring device 20 includes a plate-like conductor 201 made of a conductive metal, a local current path 202 made of a conductive metal provided in the conductor 201, and the conductor 201. An insulating layer 203 made of an insulating resin that insulates the local current path 202, a conductor 201 and a bypass circuit 204 that connects the conductor 201 and the local current path 202 outside the local current path 202, A current sensor 205 is provided in the circuit 204.

  The plate portion 200 including the conductor 201, the local current path 202, and the insulating layer 203 is inserted between the cells 10 (see FIG. 1), and both end surfaces 2011 and 2012 of the conductor 201 in the cell stacking direction are in contact with the cell 10. It is supposed to be.

  One exposed surface 2021 of the local current path 202 is exposed on one end surface 2011 of the conductor 201 and comes into contact with the cell 10. The other exposed surface 2022 of the local current path 202 is exposed on the side surface 2013 of the conductor 201 and is not in contact with the cell 10.

  A side circuit 2013 of the conductor 201 and the other exposed surface 2022 of the local current path 202 are connected by a bypass circuit 204, and a current flowing through the bypass circuit 204 is detected by a current sensor 205. .

  In the above configuration, the discharge current from the fuel cell 1 branches and flows when passing through the current measuring device 20. That is, the current flowing from the cell 10 in contact with one end face 2011 of the conductor 201 to the cell 10 in contact with the other end face 2012 of the conductor 201 is the current flowing only through the conductor 201, the local current path 202, and the detour circuit. 204 and a current flowing through the conductor 201.

  Then, the local current discharged from the portion of the local current path 202 facing the one exposed surface 2021 in the cell 10 flows through the local current path 202 and the bypass circuit 204, and thus the local current of the cell 10 is detected by the current sensor 205. can do.

  FIG. 5 is a perspective view of the air-side separator 110 viewed from the right side of FIG. As shown in FIG. 5, the air-side separator 110 includes an air inlet portion 111 and an air outlet portion 112 connected to the air flow path 20, and air for flowing air from the air inlet portion 111 toward the air outlet portion 112. And a channel groove 113. The air-side separator 110 corresponds to the first separator of the present invention, the air channel groove 113 corresponds to the oxidant gas channel of the present invention, and the air inlet 111 corresponds to the oxidant gas inlet of the present invention. The air outlet 112 corresponds to the outlet of the oxidant gas of the present invention.

  6 is a perspective view of the hydrogen-side separator 120 viewed from the right side of FIG. As shown in FIG. 6, the hydrogen separator 120 includes a hydrogen inlet 121 and a hydrogen outlet 122 connected to the hydrogen flow path 30, and hydrogen for flowing hydrogen from the hydrogen inlet 121 toward the hydrogen outlet 122. And a channel groove 123. The hydrogen separator 120 corresponds to the second separator of the present invention, the hydrogen channel groove 123 corresponds to the fuel gas channel of the present invention, and the hydrogen inlet 121 corresponds to the fuel gas inlet of the present invention. The hydrogen outlet 122 corresponds to the fuel gas outlet of the present invention.

  The local current path 202, the insulating layer 203, the detour circuit 204, and the current sensor 205 shown in FIGS. 3 and 4 are provided in a part corresponding to a part of the current measuring device 20 where the local current of the fuel cell 1 is desired to be measured. Specifically, the local current path 202, the insulating layer 203, the bypass circuit 204, and the current sensor 205 correspond to the vicinity of the air inlet portion 111 (portion indicated by reference sign B in FIG. 5) in the current measuring device 20. 3 parts of a part, a part corresponding to the vicinity of the hydrogen inlet part 121 (part shown by reference numeral C in FIG. 6) and a part corresponding to the vicinity of the hydrogen outlet part 122 (part indicated by reference numeral D in FIG. 6) Is provided.

  When the amount of humidification to the air supplied to the fuel cell 10 decreases, the portion of the electrolyte membrane of the MEA 100 near the air inlet 111 is dried. FIG. 7 shows the change over time of the current I in the drying generation portion when the electrolyte membrane dries as the air humidity ψa decreases. The proton conduction resistance increases at the drying portion in the electrolyte membrane and the current flows. descend.

  Similarly, when the amount of humidification to the hydrogen supplied to the fuel cell 10 decreases, the vicinity of the hydrogen inlet 121 in the electrolyte membrane of the MEA 100 is dried, and the proton conduction resistance increases and the current decreases at the dry portion. It should be noted that the change in current in the drying portion when the electrolyte membrane is dried along with the decrease in the amount of humidification to hydrogen is the same as in the case of the decrease in air humidity ψa shown in FIG.

  From this, the fuel cell 10 is measured by measuring the current I in the vicinity of the air inlet 111 and the hydrogen inlet 121, that is, the air inlet side current Ia · in and the hydrogen inlet side current Ih · in, which are likely to be dried. It is possible to diagnose the dry state of the electrolyte membrane. Specifically, when the air inlet side current Ia · in and the hydrogen inlet side current Ih · in are less than a predetermined current value, it can be estimated that there is a dry portion of the electrolyte membrane. The predetermined current value is set to about 90% of the current value when the electrolyte membrane is not dried.

  Conversely, when the amount of humidification to air or hydrogen becomes excessive, an excessively wet state occurs in the electrode. At that time, the liquid droplets are most likely to stay in the vicinity of the hydrogen outlet portion 122 to cause excess water, and thus are prominently generated at a portion near the hydrogen outlet portion 122 in the electrode of the MEA 100. The reason why the vicinity of the hydrogen outlet 122 is likely to be excessive in water is that water is transported from the hydrogen inlet 121 to the hydrogen outlet 122 via the hydrogen channel groove 123 and hydrogen is consumed, so that the hydrogen flow rate is increased. It is reduced and the water discharge capacity is reduced. FIG. 8 shows a change in the local current I in the excess water portion when the electrode is in an excessive water state with an increase in the water drop amount Vw at the hydrogen outlet 122, and as the water drop amount Vw increases. The permeation of gas is hindered and the output of the battery decreases.

  In addition, even when the hydrogen supply amount is insufficient with respect to the power generation amount, a shortage of hydrogen occurs from the vicinity of the hydrogen outlet portion 122, so that the current in a portion near the hydrogen outlet portion 122 in the MEA 100 decreases. FIG. 9 shows a change in the current I at a portion close to the hydrogen outlet 122 in the MEA 100 when the hydrogen supply amount Qh is insufficient. When the hydrogen shortage occurs, the current I immediately and rapidly decreases.

  From this, when the current I near the hydrogen outlet portion 122 in the MEA 100, that is, the hydrogen outlet side current Ih · out is less than a predetermined current value, it can be estimated that water is excessively generated or hydrogen is insufficiently generated. The predetermined current value is set to about 90% of the current value in the moisture excess state and the hydrogen deficiency state.

  Here, when the water is excessive and when the hydrogen shortage occurs, the current I in the portion near the hydrogen outlet 122 in the MEA 100 decreases. Therefore, it is necessary to specify which is the cause of the decrease in the current I.

  FIG. 10 shows changes in the current I near the hydrogen outlet 122 in the MEA 100 when excessive moisture occurs, and changes in the current I near the hydrogen outlet 122 in the MEA 100 when hydrogen shortage occurs. is there. FIG. 11 shows the rate of decrease in current I (hereinafter referred to as the current rate of decrease) at a site close to the hydrogen outlet 122 in the MEA 100 when excess moisture and insufficient hydrogen occur. It should be noted that the current decrease rate in this specification is the absolute value of the current change amount per unit time. In FIGS. 10 and 11, the solid line is the characteristic at the time of excess water generation, the broken line is the characteristic at the time of hydrogen shortage occurrence, and t1 is the time when the water excess or hydrogen shortage occurs.

As shown in FIGS. 10 and 11, the current I when hydrogen shortage occurs is drastically reduced as compared to when water is excessive. From this, it is possible to specify the cause of the decrease in the current I by the current decrease rate when the current decrease occurs. Specifically, when the hydrogen outlet-side current Ih · out is less than a predetermined current value and the current decrease rate is less than the predetermined decrease rate dI1 (see FIG. 11), it is estimated that moisture is excessively generated, and the hydrogen outlet-side current Ih · out When out is less than the predetermined current value and the current decrease rate is equal to or greater than the predetermined decrease rate dI1, it can be estimated that hydrogen shortage has occurred. The predetermined decrease rate dI1 is set to about 1.0 (mA / SEC / cm ² ).

  Next, a method for diagnosing the output reduction factor of the fuel cell 1 using the current measuring device 20 will be described.

  First, the air inlet side current Ia · in is measured by a current sensor 205 provided in the vicinity of the air inlet portion 111. As a result, if the air inlet side current Ia · in is less than the predetermined current value, it is diagnosed that the electrolyte membrane is dried. If the air inlet side current Ia · in is equal to or greater than the predetermined current value, the electrolyte membrane is dried. Can be diagnosed as none. In this way, when it is diagnosed that there is a dry part of the electrolyte membrane, it is estimated that the humidity ψa of the air supplied to the fuel cell 1 is low. For example, the amount of humidification of the air by the humidifier may be increased. .

  Next, the hydrogen inlet side current Ih · in is measured by a current sensor 205 provided in the vicinity of the hydrogen inlet portion 121. As a result, if the hydrogen inlet-side current Ih · in is less than a predetermined current value, it is diagnosed that there is a dried portion of the electrolyte membrane. If the hydrogen inlet-side current Ih · in is equal to or greater than the predetermined current value, the dried portion of the electrolyte membrane is diagnosed. Can be diagnosed as none. In this way, when it is diagnosed that there is a dry portion of the electrolyte membrane, it is estimated that the amount of humidification to hydrogen supplied to the fuel cell 10 is small. For example, if the amount of humidification to hydrogen by a humidifier is increased, Good.

  Next, the hydrogen outlet side current Ih · out is measured by a current sensor 205 provided in the vicinity of the hydrogen outlet portion 122. As a result, if the hydrogen outlet-side current Ih · out is equal to or greater than a predetermined current value, it can be diagnosed that no moisture excess or hydrogen shortage has occurred. When the hydrogen outlet side current Ih · out is less than the predetermined current value and the current decreasing rate of the hydrogen outlet side current Ih · out is less than the predetermined decreasing rate, it can be diagnosed that the electrode is in an excessive water state. Thus, when it is diagnosed that the electrode is in an excessive water state, it is estimated that the amount of humidification to air or hydrogen is excessive, or that the discharge capacity of water is reduced due to a decrease in the hydrogen flow rate. What is necessary is just to reduce the amount of humidification to hydrogen, and to increase a hydrogen flow rate.

  Further, when the hydrogen outlet side current Ih · out is less than a predetermined current value and the current decreasing rate of the hydrogen outlet side current Ih · out is equal to or higher than the predetermined decreasing rate, it can be diagnosed that the hydrogen supply amount is insufficient. Thus, when it is diagnosed that the hydrogen supply amount is insufficient, the hydrogen flow rate may be increased.

  According to the above-described embodiment, by providing the current measuring device 20 capable of measuring the local current in the fuel cell 1, the dry state of the electrolyte membrane based on the air inlet side current Ia · in and the hydrogen inlet side current Ih · in. Thus, excess water or shortage of hydrogen in the electrode can be diagnosed based on the hydrogen outlet side current Ih · out and the current decrease rate of the hydrogen outlet side current Ih · out. Thereby, the output reduction factor of the fuel cell 1 can be diagnosed accurately. Furthermore, the output reduction factor of the fuel cell 1 can be specified, and accordingly, accurate control according to the output reduction factor can be performed.

  For example, when the supply of hydrogen to the cell 10 is insufficient, the current density at the hydrogen outlet 122 is extremely reduced. If operation is performed in such a hydrogen-deficient state, the electrodes of the MEA 100 will be damaged, and this state must be detected and controlled to avoid it as soon as possible. Therefore, by measuring the local current in the vicinity of the hydrogen outlet 122 with the current measuring device 20 and measuring the temporal change of the local current, it is possible to diagnose the hydrogen supply state that is difficult to detect only with the cell voltage. It is. Based on this, by controlling the hydrogen supply state, it is possible to avoid as much as possible the operating state that is at risk of deterioration.

  Further, in the current measuring device 20 of the present embodiment, since the current sensor 205 is provided outside the conductor 201, interference between the current sensor 205 and the cell 10 can be avoided. Therefore, the conductor 201 can be disposed between the stacked cells 10. For this reason, the current measuring device 20 can be arranged singly or plurally at an arbitrary position in the fuel cell 1.

  For example, the cell 10 near the center of the fuel cell 1 is less likely to dissipate heat and is likely to be hot, and is easier to dry than the cell 10 near the end of the fuel cell 1. Therefore, by arranging the current measuring device 20 near the center of the fuel cell 1, it is possible to appropriately diagnose the dry state of the fuel cell 1. Moreover, since the cell 10 close to the end of the fuel cell 1 is likely to dissipate heat, the cell 10 is likely to be low in temperature and excessively moisture. Therefore, by disposing the current measuring device 20 in the vicinity of the end of the fuel cell 1, it is possible to appropriately diagnose the moisture excess state of the fuel cell 1.

(Second Embodiment)
A current measuring apparatus according to the second embodiment of the present invention will be described. In the first embodiment, the sensor 205 is arranged outside the conductor 201. However, in the second embodiment, the sensor is arranged inside the conductor 211. The current measuring device 21 is used by being attached to the fuel cell 1 as in the first embodiment.

  FIG. 12 is a perspective view of the current measuring device 21 according to the second embodiment, FIG. 13A is a front view of the main part of the current measuring device 21 of FIG. 12, and FIG. It is AA sectional drawing of a).

  As shown in FIGS. 12 and 13A, the current measuring device 21 includes a plate-like conductor 211 made of a conductive metal. The conductor 211 is inserted between the cells 10 (see FIG. 1), so that one end surface 2111 and the other end surface of the conductor 211 in the cell stacking direction are in contact with the cell 10. A rectangular parallelepiped columnar part 2113 surrounded by a square-shaped groove 2112 is formed on one end surface 2111 of the conductor 211, and the end surface of the columnar part 2113 is also in contact with the cell 10. In the example shown in FIG. 12, the groove 2112 has a square shape and the columnar portion 2113 has a rectangular parallelepiped shape. However, the present invention is not limited to this. For example, the groove 2112 has a circular shape and the columnar portion 2113 has a cylindrical shape. It can also be shaped.

  In the groove 2112, an iron core 212 is arranged so as to surround the columnar part 2113, and as shown in FIGS. 13A and 13B, Hall elements 213 are arranged between both ends of the iron core 212. The iron core 212 and the Hall element 213 constitute the magnetic sensor of the present invention.

  A groove 2114 for taking out the lead wire 213a of the Hall element 213 to the outside is formed in the conductor 211 so that the groove 2112 communicates with the outside. Further, an air inlet side passage 2115, an air outlet side passage 2116, a hydrogen inlet side passage 2117, and a hydrogen outlet side passage 2118 are formed in the conductor 211.

  In the above configuration, when a local current discharged from a portion of the cell 10 facing the columnar part 2113 flows through the columnar part 2113, a magnetic field proportional to the current is generated around the columnar part 2113. The Hall element 213 detects a magnetic field generated by the local current and converts it into a voltage. Therefore, by measuring the strength of the magnetic field of the iron core 212 part with the Hall element 213, the current flowing through the columnar part 2113 and thus the local current of the cell 10 can be detected.

  According to the present embodiment, the local current of the cell 10 can be detected by the current measuring device 21. Then, by detecting the local current of the cell 10, it is possible to specify the cause of the abnormality during the operation of the fuel cell 1.

  Moreover, since the current change at the time of occurrence of an abnormality appears earlier and more remarkably than the voltage change, the abnormality can be detected at an early stage by measuring the current.

  Further, since the iron core 212 and the hall element 213 constituting the magnetic sensor are housed in the groove 2112, interference between the magnetic sensor and the cell 10 can be avoided. Therefore, the conductor 211 can be disposed between the stacked cells 10.

  As a magnetic sensor, an MR element, an MI element, a flux gate, etc. can be used in addition to a Hall element. FIG. 14 (a) shows a front view of the main part of the current measuring device 21 when an MR element or MI element is used as the sensor element 214, and FIG. 14 (b) is a cross-sectional view taken along line AA in FIG. 14 (a). Indicates. In the case of the Hall element 213, it is necessary to arrange the longitudinal direction so as to be orthogonal to the iron core 212 (see FIG. 13B), but when an MR element or MI element is used as the sensor element 214, It can arrange | position so that a longitudinal direction may become parallel with respect to the iron core 212 (refer FIG.14 (b)). Therefore, when the MR element or the MI element is used as the sensor element, the thickness of the conductor 211 can be reduced and the thickness of the current measuring device 21 can be reduced as compared with the case where the Hall element is used. .

  The current measuring device can be incorporated in the separators 110 and 120 that constitute the cell 10. That is, a rectangular parallelepiped columnar portion surrounded by a groove is formed in the separators 110 and 120, and an iron core and a Hall element are disposed in the groove. According to this, by measuring the strength of the magnetic field of the iron core portion with the Hall element, it is possible to detect the current flowing through the columnar portion and thus the local current of the cell 10. In this case, since the separators 110 and 120 are used, it is not necessary to newly provide a plate-like conductor.

(Third embodiment)
Next, a third embodiment of the present invention will be described. The current measuring device 22 of the third embodiment has a configuration in which two conductors of the second embodiment are bonded together.

  FIG. 15 is a perspective view of the current measuring device 22 according to the third embodiment, FIG. 16A is a front view of the first conductor 221, and FIG. 16B is a diagram of the second conductor 222. 16 is a front view, and FIG. 16 is a cross-sectional view taken along the line BB in FIGS. 15 and 16.

  As shown in FIGS. 15 to 17, the current measuring device 22 of the third embodiment has two conductors 221 and 222. As shown in FIGS. 16A and 16B, one end surfaces 2211 and 2221 of the respective conductors 221 and 222 are formed in square-shaped grooves 2212 and 2222, columnar portions 2213 and 2223, and leads of Hall elements. Outlet grooves 2214 and 2224, air inlet side passages 2215 and 2225, air outlet side passages 2216 and 2226, hydrogen inlet side passages 2117 and 2227, and hydrogen outlet side passages 2218 and 2228 are formed outside the wire 224a. These are formed so as to correspond to positions when the end surfaces 2211 and 2221 formed with the columnar portions 2213 and 2223 are bonded to each other.

  As shown in FIG. 17, the iron core 223 and the Hall element (not shown) are placed in a space formed by the square-shaped grooves 2212 and 2222 when the two conductors 221 and 222 are bonded together. Be placed. The iron core 223 and the Hall element are bonded and fixed in a space formed by the square-shaped grooves 2212 and 2222 using an insulating adhesive or the like. Thereby, the square-shaped grooves 2212 and 2222, the columnar portions 2213 and 2223, the iron core 223, and the Hall element are not exposed to the outside.

  When the current measuring device 22 is arranged between the cells 10, the current measuring device 22 is sandwiched between the separators 110 and 120, and a groove-like cooling water flow channel in which cooling water normally flows on the surfaces of these separators 110 and 120. Is formed. At this time, in the configuration in which the U-shaped grooves 2212, 2222, etc. are in contact with the surfaces of the separators 110, 120, it is necessary to design the cooling water flow path of the separators 110, 120 by bypassing them. Design freedom is reduced. Therefore, by not exposing the square-shaped grooves 2212, 2222 and the like as in the present embodiment, the degree of freedom in designing the cooling water channel on the surfaces of the separators 110, 120 can be increased.

  In addition, by placing the iron core 223 in a space formed between the two conductors 221, 222, it is possible to prevent the iron core 223 from being loaded and to be distorted. Thereby, it is possible to prevent the deterioration of the magnetic characteristics of the magnetic material due to the distortion.

  18 and 19 show a modification of the current measuring device 21 of the present embodiment. 18 corresponds to FIG. 16, and FIG. 19 corresponds to FIG. As shown in FIGS. 18 and 19, a U-shaped groove 2212 and a columnar portion 2213 are formed only in the second conductor 221, and a B-shaped groove and a columnar portion are formed in the first conductor 221. Even in the configuration in which the groove is not formed, it is possible to obtain the same effect as the configuration in which the two conductors 221 and 222 are formed with a square groove or the like.

(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described. The fourth embodiment is different from the configuration of the current measuring device 22 of the third embodiment in that a buffer material for fixing the iron core and the Hall element is provided.

  20 is a cross-sectional view taken along the line BB in FIG. As shown in FIG. 20, in the current measuring device 22 of the present embodiment, when the two conductors 221 and 222 are bonded together, the buffer material 225 is formed in the space formed by the square-shaped grooves 2212 and 2222. Is filled. The iron core 223 and the Hall element (not shown) are fixed by a cushioning material 225 in a space formed by the square-shaped grooves 2212 and 2222. As the buffer material 225, for example, rubber which is a general elastic member can be used.

  Since it is necessary to insulate between the iron core 223 and the grooves 2212 and 2222, when using an insulating elastic member as the buffer material 225 or using a conductive elastic member as the buffer material 225, the iron core 223 or the groove Insulating treatment is performed by providing insulating films 2212 and 2222.

  As in this embodiment, by fixing the iron core 223 and the hall element using the buffer material 225, the iron core 223 and the hall element are prevented from rattling in the space formed by the square-shaped grooves 2212 and 2222. it can. Thereby, generation | occurrence | production of the distortion of the iron core 223 can be prevented and it becomes possible to prevent deterioration of a magnetic characteristic.

(Fifth embodiment)
Next, a fifth embodiment of the present invention will be described. The fifth embodiment is different from the current measuring device 22 of the fourth embodiment in that an elastic body is provided between two conductors 221 and 222.

  21 is a cross-sectional view taken along the line BB in FIG. As shown in FIG. 21, in the current measuring device 22 of this embodiment, an elastic body 226 having conductivity is provided between the first conductor 221 and the second conductor 222. As the elastic body 226 having conductivity, a conductive elastic member in which powder of a conductive material (for example, carbon) is mixed with rubber is used.

  As in this embodiment, by providing an elastic body 226 having conductivity between the two conductors 221, 222, it is possible to absorb variations due to processing errors and assembly errors of the cell 10 and the current measuring device 22. it can. Furthermore, it is possible to absorb thermal strain accompanying temperature changes. Thereby, the contact between the cell 10 and the conductors 221 and 222 can be improved, and the contact resistance generated between them can be reduced.

(Sixth embodiment)
Next, a sixth embodiment of the present invention will be described. The fifth embodiment is different from the configuration of the fuel cell 1 of the first embodiment in that an elastic body is provided so as to sandwich the current measuring device 20.

  FIG. 22 is a side view showing the overall configuration of the fuel cell 1 of the present embodiment. As shown in FIG. 22, in this embodiment, conductive elastic bodies 12 and 13 are provided between the cell 10 and the current measuring device 20 on both sides of the current measuring device 20. As the elastic bodies 12 and 13 having conductivity, conductive elastic members in which powder of a conductive material (for example, carbon) is mixed in rubber are used.

  As in this embodiment, by providing the elastic bodies 12 and 13 having conductivity between the cell 10 and the current measuring device 20, variations due to processing errors and assembly errors of the cell 10 and the current measuring device 20 can be absorbed. Can do. Furthermore, it is possible to absorb thermal strain accompanying temperature changes. Thereby, the contact between the cell 10 and the conductors 221 and 222 can be improved, and the contact resistance generated between them can be reduced.

(Seventh embodiment)
Next, a seventh embodiment of the present invention will be described. In the present embodiment, power generation variation in the cell plane is detected by the current measuring device.

  23 is a configuration diagram of an inspection apparatus using the current measuring device 23 according to the seventh embodiment, FIG. 24 is a perspective view of the current measuring device 23 in FIG. 23, and FIG. 25 (a) is a diagram of the current measuring device 23 in FIG. 25 is a right side view of the cell 10, FIG. 25B is a top view of the current measuring device 23 and the cell 10, FIG. 26 is a diagram illustrating an example of a measurement result of a current value for each local current measurement point, and FIG. 27 is a measurement of FIG. It is a figure which shows the electric current distribution in the cell calculated | required based on the result.

  As described above in the section “Problems to be Solved by the Invention”, when the processing variation in the cell surface of the fuel cell 1 is large, the variation in the current density is large, and the deterioration rate is increased. If a cell having a large processing variation exists in a part of the stacked cells, the cell becomes unable to generate power at an early stage. Therefore, even if other cells are normal, the battery stack cannot be operated.

  In addition, in a large-area power storage means such as a secondary battery or a capacitor formed by stacking a large number of cells, if there is an electrode joint failure in the manufacturing process, for example, the resistance of that portion increases. Variations in current occur in the plane of. If there is a portion where the power generation characteristics are locally present, the characteristics of the cell deteriorate faster than those of a cell with less current variation in the plane of the cell. However, it is not possible to detect a cell having a large local power generation variation simply by checking the current-voltage characteristics. Therefore, in a secondary battery or a capacitor configured by stacking a large number of cells, cells having different lifetimes are mixed, and reliability as an assembly is lowered.

  Therefore, in the present embodiment, the current density distribution for each cell is measured by the inspection apparatus of FIG. 23, and only the cells with little current variation are selected.

  In FIG. 23, one cell 10 in the power storage means such as the fuel cell 1 or a secondary battery or a capacitor, and a current measuring device 23 are arranged adjacent to each other in a U-shaped inspection jig 30. The The cell 10 and the current measuring device 23 are pressed against the inspection jig 30 by a pressing member 31 that can move relative to the inspection jig 30. A load device 32 that consumes power is connected to the cell 10.

  The current measurement device 23 of the present embodiment measures the local currents at a number of locations in the cell 10, the local current path 202, the insulating layer 203, the bypass circuit 204 in the current measurement device 20 of the first embodiment, A large number of devices corresponding to the current sensor 205 are provided.

  That is, as shown in FIG. 24 and FIG. 25, the current measuring device 23 includes a plate-like conductor 231 made of a conductive metal, and a large number of conductive metals provided in the conductor 231 (this example). 8) local current paths 2321 to 2328, an insulating layer (not shown) made of an insulating resin that insulates between the conductor 231 and each of the local current paths 2321 to 2328, the conductor 231 and the local current paths 2321. ˜ 2328 are provided with detour circuits 2341 to 2348 that connect between the conductor 231 and each of the local current paths 2321 to 2328 and current sensors 2351 to 2358 arranged in the respective detour circuits 2341 to 2348.

  One end surface of each local current path 2321 to 2328 is exposed on one end surface 2311 of the conductor 231, and one end surface 2311 of the conductor 231 and the exposed surface of each local current path 2321 to 2328 are in contact with the cell 10. It is like that.

  Then, the eight local currents in the cell 10 flow through the local current paths 2321 to 2328 and the bypass circuits 2341 to 2348, respectively. Therefore, the local currents in the eight locations of the cell 10 can be detected by the current sensors 2351 to 2358. it can.

  26 and FIG. 27, the vertical axis a indicates the portion where the local current is detected by the first current sensor 2351 in the cell 10, and the vertical axis b indicates the local current detected by the second current sensor 2352 in the cell 10. The vertical axis c is a part where the third current sensor 2353 detects a local current in the cell 10, and the vertical axis d is a part where the fourth current sensor 2354 is detected in the cell 10. .

  In the example shown in FIG. 26 and FIG. 27, the current value of the part d where the local current is detected by the fourth current sensor 2354 in the cell 10 is remarkably lower than the current values of the other parts ac. If the current variation is large, the cell is judged to have a quality problem and its use is prohibited. Therefore, since the fuel cell and the power storage means are configured by only cells with little current variation, the reliability thereof is improved.

(Eighth embodiment)
FIG. 28 is a perspective view of a current measuring device 23 according to the eighth embodiment of the present invention, and FIG. 29 is a front view of a main part of the current measuring device 24 of FIG. The current measurement device 24 of this embodiment can be used in place of the current measurement device 23 of the seventh embodiment.

  The current measuring device 24 of this embodiment includes a number of devices corresponding to the grooves 2112, the columnar portion 2113, the iron core 212, and the Hall element 213 in the current measuring device 21 of the second embodiment.

  That is, as shown in FIG. 28, the current measuring device 24 includes a single plate-like conductor 241 made of a conductive metal, and a rectangular shape is formed on the contact surface 2411 side of the conductor 241 with the cell. A large number (15 in this example) of rectangular parallelepiped columns 2413 surrounded by the grooves 2412 are formed. Further, as shown in FIG. 29, an iron core 242 is disposed in each groove 2412 so as to surround each columnar portion 2413, and a hall element 243 is disposed between both ends of the iron core 242. The iron core 242 and the hall element 243 constitute a magnetic sensor of the present invention.

  When this current measuring device 24 is used in place of the current measuring device 23 of the inspection device of FIG. 23, the local current of each part discharged from the portion facing the columnar part 2413 in the cell 10 corresponds to the corresponding columnar part 2413. A magnetic field proportional to the current flows and is generated around each columnar portion 2413. Therefore, by measuring the strength of the magnetic field of each iron core 242 with each Hall element 243, it is possible to detect the current flowing through each columnar portion 2413 and thus the local current in each portion of the cell 10. Then, based on the degree of variation of the 15 local currents detected in this way, it can be determined whether or not the cell has a quality problem.

(Other embodiments)
In each of the above embodiments, the fuel cell including the solid polymer electrolyte membrane is used. However, the present invention is not limited to this, and the present invention can be applied to, for example, a fuel cell including an inorganic material electrolyte.

1 is a perspective view of a fuel cell equipped with a current measuring device according to a first embodiment of the present invention. It is a side view of the fuel cell of FIG. It is a perspective view of the electric current measurement apparatus of FIG. (A) is a front view of the plate portion in the current measuring device of FIG. 1, (b) is a right side view of the plate portion, (c) is a cross-sectional view taken along line AA of (a), and (d) is ( It is sectional drawing which follows the BB line of a). It is a perspective view of an air side separator. It is a perspective view of a hydrogen side separator. It is a characteristic view which shows the change of the electric current I when drying of an electrolyte membrane generate | occur | produced. It is a characteristic view which shows the change of the electric current I at the time of the water | moisture-content excess state by the increase in the amount of water droplets of a hydrogen exit part. It is a characteristic view which shows the change of the electric current I when hydrogen supply amount is insufficient. It is a characteristic view which shows the change of the electric current I at the time of water | moisture content excess and hydrogen shortage. It is a characteristic view which shows the fall rate of the electric current I at the time of water | moisture content excess and hydrogen shortage. It is a perspective view of the electric current measurement apparatus which concerns on 2nd Embodiment. (A) is a front view of the principal part of the electric current measuring apparatus of FIG. 12, (b) is AA sectional drawing of (a). (A) is a front view of the principal part of the electric current measuring apparatus of FIG. 12, (b) is AA sectional drawing of (a). It is a perspective view of the electric current measurement apparatus which concerns on 3rd Embodiment. FIG. 16 is a plan view of the conductive material of FIG. 15. It is BB sectional drawing of FIG. FIG. 16 is a plan view of the conductive material of FIG. 15. It is BB sectional drawing of FIG. It is BB sectional drawing of FIG. 15 which concerns on 4th Embodiment. It is BB sectional drawing of FIG. 15 which concerns on 5th Embodiment. It is a side view of the fuel cell concerning a 6th embodiment. It is a block diagram of the test | inspection apparatus using the electric current measurement apparatus which concerns on 7th Embodiment. It is a perspective view of the electric current measurement apparatus of FIG. (A) is a right side view of the current measuring device and cell of FIG. 24, and (b) is a top view of the current measuring device and cell. It is a figure which shows the example of a measurement result of the electric current value for every local current measurement location. It is a figure which shows the electric current distribution in the cell calculated | required based on the measurement result of FIG. It is a perspective view of the electric current measurement apparatus which concerns on 8th Embodiment. It is a front view of the principal part of the electric current measurement apparatus of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Fuel cell (electric power apparatus), 10 ... Cell, 20, 21, 22, 23 ... Current measuring device, 201, 221, 222 ... Conductor, 2112, 2212, 2222, 2412 ... Groove, 2113, 2213, 2223, 2413 ... columnar parts, 212, 223, 242 ... iron cores, 213, 243 ... Hall elements.

Claims (6)

A current measuring device for measuring a current of a fuel cell (1) in which a plurality of cells (10) for generating electric energy by an electrochemical reaction between an oxidant gas and a fuel gas are stacked,
Plate-shaped conductors (211 and 221) that are arranged between the stacked cells and through which current from the cells flows,
In the conductor, columnar parts (2 2 13, 22 2 3) provided so as to be surrounded by the grooves (2 2 12, 22 2 2),
A magnetic sensor (212, 213, 223) that is provided in the groove and measures the strength of a magnetic field generated around the columnar portion ;
A second conductor (222) provided so as to be in contact with a surface of the conductor (221) where the columnar portion is provided ;
The columnar part and the magnetic sensor are provided in a part corresponding to at least one of a part that is easily dried in the cell, a part that tends to be excessive in water, or a part that is short of fuel gas in the conductor ,
The magnetic sensor is located in a space formed by the groove between the conductor and the second conductor, and a magnetic field generated around the columnar part when a current flows through the columnar part. A current measuring apparatus for measuring a current flowing through the columnar part by measuring the strength and converting the measured magnetic field strength into a voltage . The current measuring device according to claim 1 , wherein an elastic body (226) having conductivity is provided between the conductor and the second conductor. Wherein and the groove cushioning material for fixing (225) is provided to the magnetic sensor, between the groove and the magnetic sensor according to claim 1 or 2, characterized in that it is subjected insulating treatment The current measuring device according to 1. The magnetic sensor includes a current measuring device according to claim 1 or 2, characterized in that it is fixed by adhesive in the groove. The current measuring device according to any one of claims 1 to 4 , wherein an elastic body (12, 13) having conductivity is provided between the cell and the conductor. A current measuring device for measuring a current of a fuel cell in which a plurality of cells (10) for generating electric energy by an electrochemical reaction between an oxidant gas and a fuel gas are stacked,
In the cell, the fuel gas flow path through which the fuel gas flows and the oxidant gas flow through which the oxidant gas flows are disposed outside the electrolyte / electrode assembly (111) in which a pair of electrodes are disposed on both sides of the electrolyte membrane. A conductive separator (110, 120) in which at least one of the paths is formed;
In the separator, a columnar portion provided so as to be surrounded by the groove;
A magnetic sensor that is provided in the groove and measures the strength of the magnetic field generated in the columnar part;
The columnar part and the magnetic sensor are provided in at least one part of the separator, the part that is easily dried in the cell, the part that tends to be excessive in water, or the part that is likely to be short of fuel gas ,
The magnetic sensor measures the strength of a magnetic field generated around the columnar portion when a current flows through the columnar portion, and converts the measured magnetic field strength into a voltage, whereby a current flowing through the columnar portion. current measuring device and measuring the.

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