JP4701389B2 - Defect inspection system for electrode surface of fuel cell - Google Patents

Description

The present invention relates to a defect inspection apparatus of the electrode surface of the fuel cell, and more particularly, relates to a defect inspection apparatus of the electrode surface directly and easily the fuel cell is able to detect actual defects on the electrode surface of the fuel cell .

2. Description of the Related Art Conventionally, an inspection apparatus for a fuel cell is known in which an AC voltage is applied between a cathode and an anode of a solid oxide fuel cell to measure a load impedance, and an electrical short circuit and a gas leak are determined based on the load impedance ( For example, see Patent Document 1.)
On the other hand, a temperature distribution detector is arranged on one side of the fuel electrode layer and air electrode layer of the solid oxide fuel cell, a heat source or cooling source is arranged on the other side, and the distribution of transmitted heat is measured. 2. Description of the Related Art A solid oxide fuel cell inspection device that determines the presence or absence of defects based on the distribution of transmitted heat is known (see, for example, Patent Document 2).

Japanese Patent Laying-Open No. 2005-44715 ([0012]) Japanese Patent Laying-Open No. 2005-108801 ([Claim 10])

The conventional fuel cell inspection apparatus replaces the solid oxide fuel cell with an equivalent circuit and estimates the existence of defects indirectly, and does not directly detect actual defects. is there.
On the other hand, the above-described conventional solid oxide fuel cell inspection device directly detects actual defects, but it is necessary to transmit the heat rays almost uniformly to the inspection region of the fuel cell, There is a problem that is not easy to implement.
An object of the present invention is to provide an inspection apparatus of the electrode surface directly and easily the fuel cell is able to detect actual defects on the electrode surface of the fuel cell.

In a first aspect , the present invention relates to a plurality of magnetic sensors distributed on a sensor surface placed in parallel to an electrode surface of a fuel cell, and an electrode of the fuel cell in a state where current is taken out. And a determination means for determining whether or not there is a defect in the electrode surface of the fuel cell based on detection signals obtained by the plurality of magnetic sensors with respect to the surface. Providing equipment.
In the defect inspection apparatus for a fuel cell electrode surface according to the first aspect , a magnetic distribution generated from the electrode surface of the fuel cell in a state where current is taken out is detected by a plurality of magnetic sensors and is detected on the electrode surface of the fuel cell. It is determined whether there is a defect. That is, it is determined whether or not there is a defect by detecting magnetic distribution corresponding to the electrode surface generated in a state where current flows through the fuel cell with a plurality of magnetic sensors. According to this, the actual defect on the electrode surface of the fuel cell can be directly detected by the plurality of magnetic sensors. Further, there is no implementation difficulty that allows the heat rays to pass through the inspected area of the fuel cell almost uniformly, and the implementation is easy.

In a second aspect, the present invention provides the defect inspection apparatus for a fuel cell electrode surface according to the first aspect , wherein the determination means includes the plurality of magnetic fields for the electrode surface of the fuel cell in a state where a current is taken out. Provided is a defect inspection apparatus for an electrode surface of a fuel cell, which determines whether or not there is a defect based on a difference from an average value of detection signals obtained by a sensor.
In the defect inspection device for the electrode surface of the fuel cell according to the second aspect, the presence or absence of a defect is detected by how much the detection signal obtained by each magnetic sensor deviates from the average value of the detection signals obtained by a plurality of magnetic sensors. . This is effective when the magnetic distribution corresponding to the electrode surface of the fuel cell having no defect can be regarded as uniform or substantially uniform.

In a third aspect, the present invention provides a defect inspection apparatus of the electrode surface of the fuel cell according to the first aspect, the judging unit stores a reference data as a reference determining the presence or absence of a defect, the current The inspection data based on the detection signals obtained by the plurality of magnetic sensors and the reference data are compared with the reference data for the electrode surface of the fuel cell in a state where the fuel cell is taken out to determine whether or not there is a defect. A defect inspection apparatus for an electrode surface of a fuel cell is provided.
In the defect inspection apparatus for a fuel cell electrode surface according to the third aspect, reference data based on detection signals obtained by a plurality of magnetic sensors is stored for each electrode surface of a fuel cell having no defect, and obtained by each magnetic sensor. The inspection data based on the detected signal is compared with the stored reference data to detect the presence or absence of a defect. This is effective even when the magnetic distribution corresponding to the electrode surface of the fuel cell having no defect cannot be regarded as uniform or substantially uniform.

In a fourth aspect, the present invention provides the defect inspection apparatus for a fuel cell electrode surface according to the first aspect , wherein the determining means includes the plurality of magnetic fields on the electrode surface of the fuel cell in a state where a current is taken out. Provided is a defect inspection device for a fuel cell electrode surface, wherein it is determined whether or not a defect has occurred based on a change with time of a detection signal obtained by a sensor.
In the defect inspection apparatus for the electrode surface of the fuel cell according to the fourth aspect , the occurrence of the defect can be detected by a change in magnetic distribution when a defect occurs on the electrode surface of the fuel cell having no defect.

In a fifth aspect, the present invention provides the defect inspection apparatus for an electrode surface of a fuel cell according to any one of the first to fourth aspects , wherein the determination means includes positions of the plurality of magnetic sensors and detection signals. defects provides an electrode surface defect inspection apparatus for a fuel cell and judging whether there a portion of the electrode surface throat of the fuel cell on the basis of and.
In the defect inspection apparatus for the electrode surface of the fuel cell according to the fifth aspect, the magnetic sensor is estimated to be closest to the defect by using the fact that the closer the defect is to the magnetic sensor, the greater the influence on the detection signal. Then, it is determined in which part the defect exists from the position of the closest magnetic sensor.

In a sixth aspect, the present invention provides the defect inspection apparatus for the electrode surface of the fuel cell according to any one of the first to fifth aspects , wherein the magnetic sensor is a flux gate type magnetic detection element. Provided is a defect inspection device for an electrode surface of a fuel cell .
In the defect inspection apparatus for the electrode surface of the fuel cell according to the sixth aspect, a highly sensitive flux gate type magnetic detection element capable of detecting even a small change in magnetism due to a small defect is used, so even a small defect can be detected reliably.

In a seventh aspect, the present invention provides the defect inspection apparatus for an electrode surface of a fuel cell according to the first aspect , wherein the magnetic sensors are arranged in pairs in a direction intersecting the sensor surface, The determination means provides a defect inspection device for an electrode surface of a fuel cell, characterized in that determination is made based on a difference between detection signals obtained by the paired magnetic sensors.
There is a possibility that a magnetic sensor detects a change in external magnetism and malfunctions.
Therefore, in the defect inspection apparatus for the electrode surface of the fuel cell according to the seventh aspect , the magnetic sensors are placed in close proximity to each other, and the difference between the detection signals of the magnetic sensors is obtained. Since the change in the external magnetism has the same effect on the detection signal of the pair of magnetic sensors, it is canceled out if the difference is taken. Therefore, the influence of external magnetism can be suppressed. On the other hand, since this pair is arranged in a direction crossing the sensor surface, there is a distance to the electrode surface of the fuel cell, and the magnetism caused by the defect affects the detection signal of the paired magnetic sensor differently. . Therefore, the presence or absence of a defect can be determined from the difference.

In an eighth aspect, the present invention provides the defect inspection apparatus for a fuel cell electrode surface according to any one of the second to fifth aspects, wherein the magnetic sensors are arranged in pairs in a direction intersecting the sensor surface. The determination means is configured to determine based on a difference between detection signals obtained by the paired magnetic sensors instead of the detection signals according to any one of the second to fifth aspects. An electrode surface defect inspection apparatus for a fuel cell is provided.
There is a possibility that a magnetic sensor detects a change in external magnetism and malfunctions.
Therefore, in the defect inspection apparatus for the electrode surface of the fuel cell according to the eighth aspect, the magnetic sensors are placed close to each other and the difference between the detection signals of the magnetic sensors is obtained. Since the change in the external magnetism has the same effect on the detection signal of the pair of magnetic sensors, it is canceled out if the difference is taken. Therefore, the influence of external magnetism can be suppressed. On the other hand, since this pair is arranged in a direction crossing the sensor surface, there is a distance to the electrode surface of the fuel cell, and the magnetism caused by the defect affects the detection signal of the paired magnetic sensor differently. . Therefore, instead of the “detection signal” described in any one of the second to fifth aspects, the “difference of the detection signal obtained by the paired magnetic sensors” is used to suppress the influence of external magnetism. Thus, the presence or absence of a defect can be determined.

According to the defect inspection apparatus for the electrode surface of the fuel cell of the present invention, an actual defect of the electrode surface of the fuel cell can be directly detected by a plurality of magnetic sensors. Further, there is no implementation difficulty that allows the heat rays to pass through the inspected area of the fuel cell almost uniformly, and the implementation is easy.

  Hereinafter, the present invention will be described in more detail with reference to the embodiments shown in the drawings. Note that the present invention is not limited thereby.

FIG. 1 is a configuration diagram illustrating a defect inspection apparatus 100 for an electrode surface of a fuel cell according to a first embodiment.
The fuel cell electrode surface defect inspection apparatus 100 is based on a sensor unit 1 in which a large number of fluxgate magnetic detection elements 10 are distributed on a sensor surface 1 a and a detection signal from the sensor unit 1. And a control box 2 for determining the presence or absence of defects.

As shown in FIG. 2, the sensor unit 1 includes first to Nth fluxgate magnetic detection elements 10-1 to 10 -N and first to Nth fluxgate magnetic detection elements 10-1 to 10-10. Detection of first to N-th exciting units 50-1 to 50-N and a first to N-th flux gate type magnetic sensing elements 10-1 to 10-N for energizing an exciting current to -N exciting coils First to N-th signal processing units 20-1 to 20-N that process signals induced in the coils for use to output first to N-th detection signals, and analog to first to N-th detection signals 1 to N-th A / D converters 40-1 to 40-N for digital conversion.
Further, the control box 2 reads the first to Nth detection signals from the first to Nth A / D converters 40-1 to 40-N, and whether or not there is a defect based on each detection signal. A microprocessor 60 for determining whether or not, and an input / output unit 61 for receiving an instruction from an operator and outputting a determination result.

  FIG. 3 shows the flux gate type magnetic sensing element 10 (10-1 to 10-N), the excitation unit 50 (50-1 to 50-N), and the signal processing unit 20 (20-1 to 20-N). FIG.

  The fluxgate type magnetic sensing element 10 includes an excitation coil 12 and a detection coil 13 formed on a magnetic core 11 formed in an annular shape from a material having soft magnetic properties (low coercive force and high magnetic permeability) such as permalloy or sendust. It is the structure which provided. A structure in which an excitation coil and a detection coil are attached to a rod-shaped magnetic core may be used.

  The excitation unit 50 includes an oscillator 51 that oscillates a rectangular wave having a frequency f0 (for example, f0 = 2 kHz), and a coil that divides the rectangular wave oscillated by the oscillator 51 and energizes the excitation coil 12 with an alternating current having a frequency f0 / 2. A drive circuit 52 is included, and an alternating current is passed through the exciting coil 12 of the fluxgate magnetic detection element 10.

  The signal processing unit 20 outputs a feedback circuit 26 that superimposes the feedback signal Ib on the detection signal Is induced in the detection coil 13, and a synchronization signal that is shifted in phase from the excitation phase shift of the flux gate type magnetic detection element 10. A phase shifter 31, a preamplifier 32 for amplifying the detection signal Is superimposed with the feedback signal Ib, a high-pass filter 33 for cutting off the excitation signal component at the cutoff frequency fc1 (> f0 / 2), and a high-pass filter 33, a phase detector 34 for detecting the phase of the output signal from the synchronization signal, a low-pass filter 35 for extracting the output signal Vp in the desired band at the cutoff frequency fc2 (<< f0), and integrating the output signal Vp with a time constant τ1. A first integrator 41 that outputs one integration signal Vi1, a second integrator 42 that integrates the first integration signal Vi1 with a time constant τ2 (> τ1), and outputs a second integration signal Vi2. First A second integrator 43 that integrates the second integrated signal Vi2 with a time constant τ3 (> τ2) and outputs a third integrated signal Vi3; and a first integrator 3 that attenuates / amplifies the first to third integrated signals Vi1 to Vi3. An adder 21 that adds the first to third integration signal adjusters 201 to 203 and the first to third integration signals Vi1 ′ to Vi3 ′ that have passed through the integration signal adjusters 201 to 203 and outputs an addition signal Vd; A feedback amount adjuster 22 for attenuating / amplifying the added signal Vd to adjust the sensitivity, and a bias adjuster 23 for adding the bias signal Va to the added signal Vd ′ having passed through the feedback amount adjuster 22 and outputting the feedback signal Ib, It has.

  The bias signal Va is adjusted so that the addition signal Vd becomes 0 (that is, the DC component of noise magnetism is canceled) when there is no magnetic object in the vicinity.

  By adjusting the time constants τ1, τ2, τ3 and feedback characteristics of the integrators 41, 42, and 43 with the integral signal adjusters 201 to 203, the band of the signal component extracted from the output signal Vp is changed for each integrator. Thus, signal components of different bands can be obtained simultaneously as detection signals. That is, an appropriate one of the first to third integration signals Vi1 to Vi3 may be selected as the detection signal.

FIG. 4 is an explanatory diagram of a state in which a defect of the fuel cell F is inspected. In addition, in order to make it easy to understand, although the fuel cell F is drawn smaller than the sensor unit 1, it is actually the same area.
The fuel cell F includes an anode gas introduction part A, a porous anode P, an electrolyte Y, a porous cathode N, and a cathode gas introduction part H. A load R is connected between the porous anode P and the porous cathode N, and a current I is taken out.
The defect inspection apparatus 100 for the electrode surface of the fuel cell is installed with its sensor surface 1a parallel to the porous cathode N of the fuel cell F.

FIG. 5 is a flowchart illustrating a defect inspection process for the electrode surface of the fuel cell according to the first embodiment.
In step S1, the microprocessor 60 reads the first to Nth detection signals from the first to Nth fluxgate magnetic detection elements 10-1 to 10-N.
In step S2, an average value of the first to Nth detection signals is obtained.
In step S3, the average value of the first to Nth detection signals and each difference (absolute value) between the first to Nth detection signals and a predetermined value (positive value) are compared, and all the differences are predetermined values. If it is smaller, the process proceeds to step S4, and if even one difference is equal to or greater than the predetermined value, the process proceeds to step S5.

  In step S4, it is determined that there is no defect. Then, the process proceeds to step S7.

In step S5, it is determined that a defect exists.
In step S6, the average value of the first to Nth detection signals and the difference between the first to Nth detection signals and the positions of the first to Nth fluxgate magnetic detection elements 10-1 to 10-N ( As shown conceptually in FIG. 6, a contour map h is created based on the information obtained in advance, and a region on the contour map h is extracted as an estimated defect existence region. Then, the process proceeds to step S7.

  In step S7, if it is determined that there is no defect, this is notified. On the other hand, when it is determined that a defect exists, a message display M and an estimated presence area L indicating that a defect exists are displayed as shown in FIG. Then, the process ends.

According to the defect inspection apparatus 100 for the electrode surface of the fuel cell according to the first embodiment, the following effects can be obtained.
(1) The actual defects on the electrode surface of the fuel cell F can be directly detected by the first to Nth fluxgate type magnetic sensing elements 10-1 to 10-N.
(2) The implementation is easy because there is no implementation difficulty that allows heat rays to pass through the inspected area of the fuel cell F almost uniformly.
(3) Since the high-sensitivity fluxgate type magnetic detection elements 10-1 to 10-N that can detect small magnetic changes due to small defects are used, even small defects can be detected reliably.
(4) The position of the defect can be detected.
(5) The inspection reflecting the actual operation state of the fuel cell (the state where the current I is taken out) can be performed. It is also possible to inspect by applying an AC voltage between the cathode and the anode.

FIG. 8 is a flowchart showing the defect inspection process for the electrode surface of the fuel cell according to the second embodiment.
The microprocessor 60 stores in advance each reference data based on detection signals obtained by the first to Nth fluxgate type magnetic detection elements 10-1 to 10-N for the fuel cell F having no defect.
In step S11, the microprocessor 60 reads out the stored reference data.
In step S12, the first to Nth detection signals are read from the first to Nth fluxgate type magnetic detection elements 10-1 to 10-N.
In step S13, the difference (absolute value) between each reference data and the first to Nth detection signals is compared with a predetermined value (positive value). If all the differences are smaller than the predetermined value, the process proceeds to step S14. If even one difference is greater than or equal to the predetermined value, the process proceeds to step S15.

  In step S14, it is determined that there is no defect. Then, the process proceeds to step S17.

In step S15, it is determined that a defect exists.
In step S16, a contour map is created based on the differences between the reference data, the first to Nth detection signals, and the positions of the first to Nth fluxgate type magnetic detection elements 10-1 to 10-N. Then, the region of the contour map is extracted as the estimated existence region of the defect. Then, the process proceeds to step S17.

  In step S17, if it is determined that there is no defect, this is notified. On the other hand, when it is determined that a defect exists, a message display indicating that a defect exists and an estimated presence area are displayed. Then, the process ends.

FIG. 9 is a flowchart showing the defect inspection process for the electrode surface of the fuel cell according to the third embodiment.
This process is repeatedly executed every predetermined time (for example, 30 minutes). In the first execution, only step S22 is executed, and the detection signals obtained by the first to Nth fluxgate type magnetic detection elements 10-1 to 10-N for the fuel cell F are stored. In the second and subsequent executions, steps S21 to S27 are executed.

In step S21, the microprocessor 60 reads each previous detection signal stored.
In step S22, the first to Nth detection signals are read from the first to Nth fluxgate type magnetic detection elements 10-1 to 10-N.
In step S23, each difference (absolute value) of the first to Nth detection signals of the previous time and this time is compared with a predetermined value (positive value). If all the differences are smaller than the predetermined value, the process proceeds to step S24. If even one difference is equal to or greater than the predetermined value, the process proceeds to step S25.

  In step S24, it is determined that there is no defect. Then, the process proceeds to step S27.

In step S25, it is determined that a defect exists.
In step S26, a contour map is created based on the differences between the first to Nth detection signals of the previous time and the current time and the positions of the first to Nth fluxgate type magnetic detection elements 10-1 to 10-N. Then, the region of the contour map is extracted as the estimated existence region of the defect. Then, the process proceeds to step S27.

  In step S27, if it is determined that there is no defect, this is notified. On the other hand, when it is determined that a defect exists, a message display indicating that a defect exists and an estimated presence area are displayed. Then, the process ends.

FIG. 10 is a configuration diagram illustrating a defect inspection apparatus 200 for an electrode surface of a fuel cell according to a fourth embodiment.
Defect inspection apparatus 200 of the electrode surface of the fuel cell, the underside of each flux gate type magnetic sensor 10 of the defect inspection apparatus 100 of the electrode surface of the fuel cell of Example 1, fluxgate magnetic them to become paired The configuration includes a detection element 10.

The defect inspection process for the electrode surface of the fuel cell is performed by replacing the “first to Nth detection signals” in FIGS. 5, 8, and 9 with “the first to Nth detection signals and the N + 1 to Nth detection signals paired therewith”. What is necessary is just to read as 1st-Nth difference which is each difference (absolute value) of 2N detection signals.

According to the defect inspection apparatus 200 for the electrode surface of the fuel cell of Example 4, the difference between the detection signal pairs of the fluxgate type magnetic detection element is taken, so that the influence of external magnetism can be suppressed.

  A SQUID, a Hall element, an MR element, or the like may be used instead of the fluxgate type magnetic detection element.

The electrode surface defect inspection apparatus of the present invention can be used as a fuel cell defect inspection apparatus.

1 is a schematic diagram illustrating a configuration of a defect inspection apparatus for an electrode surface of a fuel cell according to Example 1. FIG. 1 is a block diagram illustrating a configuration of a defect inspection device for an electrode surface of a fuel cell according to Example 1. FIG. It is a block diagram which shows a fluxgate type | mold magnetic detection element, an excitation part, and a signal processing part. It is explanatory drawing of the state which test | inspects the defect of a fuel cell. 2 is a flowchart showing a defect inspection process for an electrode surface of a fuel cell according to Example 1. FIG. It is explanatory drawing of a contour map. It is explanatory drawing which shows the example of a display when a defect is detected. 6 is a flowchart showing a defect inspection process for an electrode surface of a fuel cell according to Example 2. FIG. 6 is a flowchart showing a defect inspection process for an electrode surface of a fuel cell according to Example 3. FIG. FIG. 10 is a schematic diagram illustrating a configuration of a defect inspection apparatus for an electrode surface of a fuel cell according to Example 4;

DESCRIPTION OF SYMBOLS 1 Sensor unit 2 Control box 10, 10-1 to 10-2N Flux gate type magnetic detection element 11 Magnetic core 12 Excitation coil 13 Detection coil 20, 20-1 to 20-N Signal processor 50, 50-1 to 50 -N Excitation Unit 60 Microprocessor 61 Input / Output Unit 100,200 Defect inspection device for fuel cell electrode surface F Fuel cell

Claims (1)

A plurality of magnetic sensors distributed on a sensor surface placed parallel to the electrode surface of the fuel cell, and detection signals obtained by the plurality of magnetic sensors for the electrode surface of the fuel cell in the operating state And determining means for determining whether or not the electrode surface of the fuel cell is defective based on the position of the plurality of magnetic sensors and each detection signal. A defect inspection device for an electrode surface of a fuel cell, characterized in that it is determined on which part of the electrode surface of the fuel cell.

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