Electrical resistance measuring device

Abstract

To provide an electric resistance measuring device capable of accurately measuring the electric resistance of a plate-like workpiece having a large area relative to the thickness.SOLUTION: An electrical resistance measurement device for measuring electrical resistances of a plurality of joint portions of a workpiece in which a corrugated member including a plurality of crest portions and trough portions and a flat plate-shaped member are laminated in a thickness direction and contact portions between the trough portions and the flat plate-shaped member are joined, the electrical resistance measurement device comprising at least two sets of an upper electrode and a lower electrode that sandwich a position of the crest portion of the workpiece from the thickness direction, wherein in a top view, longitudinal dimensions of the upper electrode and the lower electrode are larger than a longitudinal dimension of the crest portion.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to an electrical resistance measuring device. [Background technology]

[0002] Measuring the electrical resistance of a flat workpiece (such as a flat-plate stacked fuel cell unit) that has a large area relative to its thickness requires a high-performance measuring instrument because the electrical resistance in the thickness direction is very small, and accurate measurement is difficult with a single set of electrodes because a current distribution occurs within the surface. Patent Document 1 discloses a fuel cell impedance measuring device that measures the in-plane distribution of current density and the like by making measurements by contacting multiple measuring terminals within the surface of the fuel cell. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-27712 Summary of the Invention [Problem to be solved by the invention]

[0004] In the case of a solid oxide fuel cell, a gas flow path extending along one side of the cell may be formed by joining a corrugated flow path member and a separator. In such a workpiece, the joint also extends along one side of the cell. The measuring device described in the above document is configured to contact measurement terminals with each measurement area divided into vertical and horizontal directions on the surface of the workpiece. Therefore, when used to measure the electrical resistance of a workpiece having a joint extending along one side of the cell, there will be areas where the measurement terminals do not contact, making accurate measurement impossible.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an electrical resistance measuring device that can accurately measure the electrical resistance of a flat workpiece that has a large area relative to its thickness. [Means for solving the problem]

[0006] According to one aspect of the present invention, there is provided an electrical resistance measuring device for measuring the electrical resistance of multiple joints of a workpiece formed by stacking a corrugated member having multiple peaks and valleys and a flat member in the thickness direction and joining the contact portions between the valleys and the flat member. This electrical resistance measuring device includes at least two pairs of upper and lower electrodes that sandwich the peaks of the workpiece from the thickness direction, and the longitudinal dimensions of the upper and lower electrodes are greater than the longitudinal dimension of the peaks when viewed from above. [Effects of the Invention]

[0007] According to the above aspect, the electrical resistance can be measured with high accuracy even in a fuel cell having a joint extending along one side of the cell. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing an electrical resistance measuring device. [Figure 2] FIG. 2 is a diagram showing a positioning jig. [Figure 3] FIG. 3 is an exploded view of the workpiece. [Figure 4] FIG. 4 is a cross-sectional view showing a state in which the workpiece is sandwiched between the upper electrode and the lower electrode from above and below. [Figure 5] FIG. 5 is a plan view showing a state in which the workpiece is sandwiched between the upper electrode and the lower electrode from above and below. [Figure 6] FIG. 6 is a cross-sectional view showing a state in which the central axes of the upper electrode and the lower electrode are misaligned. [Figure 7] FIG. 7 is a diagram showing the positional relationship between the current application unit and the current extraction unit according to this embodiment. [Figure 8] FIG. 8 is a diagram showing the positional relationship between the current application unit and the current extraction unit according to the comparative example. [Figure 9] FIG. 9 is a diagram showing a state in which a workpiece is set on the lower electrode. [Figure 10] FIG. 10 is a diagram showing a state in which the upper electrode is set. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0010] [Overall configuration] 1 is a diagram showing an electrical resistance measuring device 1 according to an embodiment of the present invention. The electrical resistance measuring device 1 according to this embodiment is used to measure the electrical resistance value of a flat plate-shaped workpiece 2, such as a flat plate stacked fuel cell, which has a large area relative to its dimension in the thickness direction (z-axis direction in the figure).

[0011] The electrical resistance measuring device 1 includes a plurality of pairs of electrodes (upper electrode 3 and lower electrode 4) that sandwich the workpiece 2 from above and below (both sides in the z-axis direction in the drawing). The upper electrode 3 and the lower electrode 4 are both flat plate-like members with predetermined thicknesses (WU, WL in FIG. 4). The predetermined thicknesses WU and WL will be described later.

[0012] The plurality of lower electrodes 4 are arranged on the upper surface of the base 6 with their longitudinal directions parallel to each other at predetermined intervals, with their flat portions 4A perpendicular to the upper surface of the base 6. The predetermined intervals are determined according to the arrangement of the peaks 34 and the upper electrode 3, which will be described later.

[0013] The upper electrodes 3 are arranged with their longitudinal directions parallel to each other, with their flat portions 3A perpendicular to the top surface of the base 6 and facing the lower electrode 4 across the workpiece 2. Insulator blocks 12 are arranged between adjacent upper electrodes 3.

[0014] The lower electrode 4 and the upper electrode 3 are positioned in the y-axis direction by abutting one end of the longitudinal direction against a stopper 13. The lower electrode 4 is positioned in the x-axis direction by a positioning pin 17.

[0015] A positioning jig 5 for determining the relative positions of the upper electrode 3 and the lower electrode 4 is disposed on the other end in the longitudinal direction.

[0016] 2 is a diagram showing the positioning jig 5. The positioning jig 5 has an upper electrode groove 5A into which the upper electrode 3 fits, and a lower electrode groove 5B into which the lower electrode 4 fits, on the same surface. The central axes of the upper electrode groove 5A and the lower electrode groove 5B (the dashed line and the two-dot dashed line in the figure) are aligned on the same line. In other words, the positioning jig 5 positions the upper electrode 3 and the lower electrode 4 so that their central axes are aligned on the same line.

[0017] Returning to the explanation of Figure 1.

[0018] The electrical resistance measuring device 1 includes a shaft 14 that passes through the plurality of lower electrodes 4 arranged as described above, and a nut 15 that secures the shaft 14 to the lower electrode 4. A lead wire 11 for extracting current is connected to the shaft 14 for each lower electrode 4. As a result, the shaft 14 also functions as a current extracting unit 9. The electrical resistance measuring device 1 also includes shafts 18 and 20 that pass through the plurality of upper electrodes 3 arranged as described above, and nuts 19 and 21 that secure the shafts 18 and 20 to the upper electrode 3. A lead wire 10 for applying current is connected to the shaft 20 for each upper electrode 3. As a result, the shaft 20 also functions as a current applying unit 8. The current applying unit 8 and the current extracting unit 9 of the pair of upper electrode 3 and lower electrode 4 are arranged on opposite sides of the longitudinal direction when viewed from above. It is desirable that the current applying unit 8 be located higher in the z-axis direction of the upper electrode 3, and the current extracting unit 9 be located lower in the z-axis direction of the lower electrode 4.

[0019] As described above, the electrical resistance measuring device 1 measures the electrical resistance of the workpiece 2 by sandwiching the workpiece 2 between the upper electrode 3 and the lower electrode 4 from above and below and passing a current from the current application unit 8 to the current extraction unit 9. For accurate measurement, it is desirable to have a low contact resistance between the workpiece 2 and each electrode 3, 4. Therefore, the electrical resistance measuring device 1 of this embodiment is equipped with a load transmission member 7 that applies a load from above the upper electrode 3. Note that if there is variation in the end position of the upper electrode 3 in the height direction (z-axis direction) due to dimensional tolerances of each component or temperature changes, the load will not be applied uniformly, resulting in variation in the contact resistance and reduced measurement accuracy. Therefore, the electrical resistance measuring device 1 of this embodiment interposes an elastic member 16 between the load transmission member 7 and the upper electrode 3. As a result, even if there is variation in the end position of the upper electrode 3 in the height direction, the variation is absorbed by the elastic member 16, thereby making the load more uniform. Note that the elastic member 16 may be disposed between the base 6 and the lower electrode 4.

[0020] The elastic modulus K of the elastic member 16 is defined, for example, as in equation (1).

[0021] K=ΔF / (Xmax-Xmin) (1)

[0022] Here, ΔF is the difference between the maximum and minimum values ​​of the applied load within the tolerance range. Xmax is the amount of compression caused by the upper electrode 3 whose upper end in the z-axis direction is at the highest position within the tolerance range. Xmin is the amount of compression caused by the upper electrode 3 whose upper end in the z-axis direction is at the lowest position within the tolerance range.

[0023] [Work] Next, Work 2 will be described.

[0024] 3 is an exploded view of the work 2. In this embodiment, the case where the work 2 is a battery cell of a solid oxide fuel cell will be described. However, the work 2 to be measured by the electrical resistance measuring device 1 according to this embodiment is not limited to this.

[0025] The workpiece 2 includes an interconnector 30 as a flat plate member, a flow path member 31 as a corrugated member, a joining member 32 that joins the interconnector 30 and the flow path member 31, and a membrane electrode assembly (MEA) 33.

[0026] The interconnector 30 is a flat plate made of, for example, stainless steel, titanium, or the like.

[0027] The flow path member 31 has a corrugated plate shape in the yz cross section, with later-described peaks 34 and valleys 35 adjacent to each other. The peaks 34 and valleys 35 extend from one end to the other end in the x-axis direction in the drawing.

[0028] The joining member 32 melts when heated to join the interconnector 30 and the flow path member 31. In this embodiment, copper foil is used as the joining member 32, but other materials may be used as long as they have a joining function and electrical conductivity.

[0029] [Relationship between workpiece and electrode] Next, the relationship between the workpiece 2 and the upper and lower electrodes 3 and 4 will be described.

[0030] Fig. 4 is a diagram showing the state in which the workpiece 2 is sandwiched from above and below between the upper electrode 3 and the lower electrode 4, and is a part of the xz cross section of Fig. 1. Fig. 5 is a diagram (plan view) showing the state in which the workpiece 2 is sandwiched from above and below between the upper electrode 3 and the lower electrode 4.

[0031] As shown in FIG. 4, the channel member 31 has valleys 35 joined to the interconnector 30 via joining members 32, and peaks 34 adjacent to the valleys 35 protrude in the z-axis direction from the surface of the interconnector 30. The upper electrode 3 contacts each peak 34 from above in the z-axis direction, and the lower electrode 4 is positioned opposite the upper electrode 3 with the workpiece 2 sandwiched therebetween. The pair of opposing upper and lower electrodes 3 and 4 are positioned by the positioning jig 5 so that their central axes CU and CL are aligned on the same line. It is desirable that the central axes CU and CL of the upper and lower electrodes 3 and 4 coincide with the central axis CM of the peak 34 in a top view. It is also desirable that the lateral dimension of the lower electrode 4 in a top view (dimension WL in FIG. 4) be larger than the lateral dimension of the upper electrode 3 in a top view (dimension WU in FIG. 4).

[0032] As shown in Fig. 5, the upper electrode 3 and the lower electrode 4 are arranged parallel to the peaks 34 and valleys 35. The longitudinal dimensions of the upper electrode 3 and the lower electrode 4 (dimensions LU and LL in Fig. 5) are greater than the longitudinal dimension of the peaks 34 (dimension LM in Fig. 5). It is desirable that the lateral dimension of the upper electrode 3 (dimension WU in Fig. 5) be equal to or greater than the width of the peaks 34 (dimension WM in Fig. 5).

[0033] That is, a configuration that satisfies all of the following conditions is more desirable.

[0034] First condition: When viewed from above, the central axes CU, CL, and CM of the upper electrode 3, the lower electrode 4, and the peaks 34 are aligned on the same line.

[0035] Second condition: The widthwise dimension WL of the lower electrode 4 is greater than the widthwise dimension WU of the upper electrode 3.

[0036] Third condition: The longitudinal dimensions LU and LL of the upper electrode 3 and the lower electrode 4 are greater than the longitudinal dimension LM of the ridge portion .

[0037] Fourth condition: The width WU of the upper electrode 3 in the lateral direction is equal to or greater than the width WM of the ridges 34 .

[0038] [Electrical resistance measurement] When measuring the electrical resistance in the thickness direction of a thin plate-like sample such as the workpiece 2, the following problem arises.

[0039] First, in the case of low-resistance samples such as fuel cells, the potential difference between the two electrodes is small, so accurate measurement using only a pair of upper and lower electrodes requires high-performance measuring equipment.

[0040] Second, when measurements are made using only a pair of upper and lower electrodes, differences in current density occur within the sample, making accurate measurements difficult.

[0041] However, the electrical resistance measuring device 1 according to this embodiment can solve these problems as described below.

[0042] First, we will explain why the first problem can be solved. The electrical resistance measuring device 1 of this embodiment uses multiple pairs of upper and lower electrodes 3 and 4 for measurement. This reduces the contact area between each electrode and the workpiece 2 compared to measurement using only one pair of electrodes. This increases the voltage applied to each electrode, thereby increasing the resistance value, making measurement easier. Furthermore, by satisfying the first to fourth conditions above, the entire peaks 34 can be covered by the upper electrode 3. This allows current to be applied to the valleys 35, which are the joints, from the entire peaks 34 adjacent to the valleys 35. Therefore, if there is a joint defect or other problem at any location in the joint, it can be detected from the distribution of resistance values. Furthermore, if the width WU of the upper electrode 3 is set to be larger than the width WM of the peaks 34, even when dimensional tolerances are taken into account, the upper electrode 3 can cover the entire peaks 34, even if dimensional deviations due to tolerances or other factors occur.

[0043] Furthermore, when the widthwise dimension WL of the lower electrode 4 and the widthwise dimension WU of the upper electrode 3 are the same, if the positions of the central axes CU and CL of the upper electrode 3 and the lower electrode 4 are misaligned as shown in Figure 6, shear stress may be generated in the area of ​​the interconnector 30 surrounded by the dashed line in the figure when a load is applied from above, resulting in deformation. However, by satisfying the second condition above, it is possible to prevent the generation of shear stress even if the positions of the central axes CU and CL are misaligned due to assembly tolerances, dimensional tolerances, etc.

[0044] Next, the reason why the second problem can be solved will be explained. Fig. 7 is a diagram showing the positional relationship between the current application unit 8 and the current extraction unit 9 of the electrical resistance measuring device 1 according to this embodiment. Fig. 8 is a diagram showing a comparative example.

[0045] 7 is a simplified yz cross section of the portion where the workpiece 2 is sandwiched between the upper electrode 3 and the lower electrode 4. The current application unit 8 is provided at one end of the upper electrode 3 in the y axis direction, near the upper end in the z axis direction, and the current extraction unit 9 is provided at the other end of the lower electrode 4 in the y axis direction, near the lower end in the z axis direction. In other words, the current application unit 8 and the current extraction unit 9 are arranged on the diagonal of the rectangular cross section formed by the upper electrode 3, the workpiece 2, and the lower electrode 4.

[0046] In contrast to this, in the comparative example of FIG. 8, the current application section 8 and the current extraction section 9 are arranged on the same side of the rectangular cross section formed by the upper electrode 3, workpiece 2, and lower electrode 4.

[0047] Electric current has the tendency to flow through paths that allow it to flow easily. In other words, when flowing through the same material, the shorter the path length, the lower the resistance and the easier it is for the current to flow. Therefore, in the configuration of the comparative example, the current density is high in the areas close to the current application unit 8 and the current extraction unit 9, and the further away from the current application unit 8 and the current extraction unit 9, the lower the current density, resulting in greater variation in current density.

[0048] In contrast, in the configuration of this embodiment, the difference in flow path length between the different flow paths from the current application unit 8 to the current extraction unit 9 is small, so the variation in current density is smaller than in the comparative example. Note that by increasing the electrode height (HU, HL in FIG. 7), the variation in current density can be further reduced.

[0049] [How to set the electrode and workpiece] 9 and 10 are diagrams showing the procedure for setting the upper electrode 3, the lower electrode 4 and the workpiece 2 for measuring electrical resistance.

[0050] As shown in Figure 9, after setting the lower electrode 4 on the pedestal 6, the workpiece 2 is set on the lower electrode 4. At this time, it is necessary to align the positions of the lower electrode 4 and the peaks 34 of the workpiece 2. The lower electrode 4 may be set while checking the position of the peaks 34, or a shaft 40 may be provided to position the workpiece 2 in the x-axis direction. Setting the shaft 40 in a position where the lower electrode 4 and the peaks 34 are aligned when the workpiece 2 is in contact with the shaft 40 makes it easier to set the workpiece 2.

[0051] After the workpiece 2 is set, the upper electrode 3 is set from above the workpiece 2, and an insulator block 12 is placed between adjacent upper electrodes 3. Then, a shaft 18 is passed through the multiple upper electrodes 3 and fixed with a nut 19. Thereafter, the above-mentioned shaft 20, nut 21, lead wire 10 for applying current, and lead wire 11 for extracting current are attached, and the load transmission member 7 is set, thereby making it possible to perform measurements.

[0052] [Action and effect] As described above, according to this embodiment, an electrical resistance measuring device 1 is provided that measures the electrical resistance of multiple joints of a workpiece 2 in which a flow path member (corrugated member) 31 having multiple peaks 34 and valleys 35 and an interconnector (flat member) 30 are stacked in the thickness direction, and the contact portions between the valleys 35 and the interconnector 30 are joined. This device includes at least two pairs of upper electrodes 3 and lower electrodes 4 that sandwich the peaks 34 of the workpiece 2 from the thickness direction. In a top view, the longitudinal dimensions LU and LL of the upper electrode 3 and the lower electrode 4 are larger than the longitudinal dimension LM of the peaks 34. As a result, the upper electrode 3 contacts the peaks 34 over the entire area in the y-axis direction, and current is applied from the entire peaks 34 adjacent to the joint. As a result, the electrical resistance of the entire joint of the workpiece 2 can be measured, and any poor joints in some of the valleys 35 can be detected.

[0053] In the electrical resistance measuring device 1 according to this embodiment, the upper electrode 3 covers the peaks 34 in a top view, and the lower electrode 54 is positioned opposite the upper electrode 3 across the workpiece 2. This allows the upper electrode 3 to cover the entire peaks 34, enabling more accurate measurement of electrical resistance.

[0054] In the electrical resistance measuring device 1 according to this embodiment, the width WU of the upper electrode 3 in the top view is equal to or greater than the width WM of the peaks 34. This allows the upper electrode 3 to cover the entire peaks 34 even if misalignment occurs between the upper electrode 3 and the peaks 34 due to various tolerances.

[0055] In the electrical resistance measuring device 1 according to this embodiment, the upper electrode 3 and the lower electrode 4 are arranged parallel to the peaks 34 and valleys 35. A positioning jig 5 is also provided to determine the relative positions of the upper electrode 3 and the lower electrode 4. The positioning jig 5 has an upper electrode groove 5A into which the upper electrode 3 fits and a lower electrode groove 5B into which the lower electrode 4 fits, on the same surface, with the central axes of the upper electrode groove 5A and the lower electrode groove 5B aligned on the same line. The lateral dimension WL of the lower electrode 4 in a top view is larger than the lateral dimension WU of the upper electrode 3 in a top view. This allows the upper electrode 3 and the lower electrode 4 to be positioned relative to each other, preventing the load from the upper electrode 3 from being applied to areas where the lower electrode 4 is not present, even when assembly tolerances and dimensional tolerances are large.

[0056] In the electrical resistance measuring device 1 according to this embodiment, the current application unit 8 and the current extraction unit 9 of the pair of upper and lower electrodes 3 and 4 are arranged on opposite sides in the longitudinal direction when viewed from above. This makes it possible to suppress variations in the current density distribution inside the electrodes and to measure the resistance value with high accuracy.

[0057] The electrical resistance measuring device 1 according to this embodiment further includes a base 6 on which the lower electrode 4 is placed, and a load transmission member 7 that transmits a load to the upper electrode 3 in the direction of the base 6, and an elastic member 16 is interposed at least between the upper electrode 3 and the load transmission member 7 or between the lower electrode 4 and the base 6. This absorbs variations in the position of the upper end of the upper electrode 3 caused by assembly tolerances, dimensional tolerances, temperature changes, etc., and makes it possible to equalize the load.

[0058] In the above embodiment, a configuration has been described in which one upper electrode 3 and one lower electrode 4 are provided for one peak 34, but the present invention is not limited to this. A configuration in which multiple peaks 34 are sandwiched between a pair of upper electrodes 3 and lower electrodes 4 may also be used, as long as the effect of increasing the voltage applied to each electrode can be obtained, thereby making the resistance value easier to detect.

[0059] Although the embodiments of the present invention have been described above, the above embodiments merely illustrate some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above embodiments. [Explanation of symbols]

[0060] REFERENCE SIGNS LIST 1 Electrical resistance measuring device, 2 Workpiece, 3 Upper electrode, 4 Lower electrode, 5 Positioning jig, 6 Base, 7 Load transfer member, 30 Interconnector, 31 Flow path member, 32 Joining member, 33 Membrane electrode assembly, 34 Peak portion, 35 Valley portion

Claims

1. An electrical resistance measuring device for measuring the electrical resistance of a plurality of joints of a workpiece in which a corrugated member having a plurality of peaks and valleys and a flat plate-like member are stacked in the thickness direction and the contact portions between the valleys and the flat plate-like member are joined, At least two pairs of upper and lower electrodes are provided to sandwich the position of the peak of the workpiece from the thickness direction, 10. An electrical resistance measuring device, wherein, when viewed from above, the longitudinal dimensions of the upper electrode and the lower electrode are greater than the longitudinal dimension of the peaks.

2. 2. The electrical resistance measuring device according to claim 1, the upper electrode covers the peak portion in a top view, The lower electrode is disposed in a position facing the upper electrode across the workpiece.

3. 3. The electrical resistance measuring device according to claim 2, An electrical resistance measuring device, wherein the dimension of the upper electrode in the short side direction when viewed from above is equal to or greater than the width of the peak portion.

4. 2. The electrical resistance measuring device according to claim 1, The upper electrode and the lower electrode are arranged parallel to the peaks and valleys.

5. 2. The electrical resistance measuring device according to claim 1, a positioning jig for determining the relative positions of the upper electrode and the lower electrode; the positioning jig has an upper electrode groove into which the upper electrode is fitted and a lower electrode groove into which the lower electrode is fitted, on the same surface; the central axes of the upper electrode groove and the lower electrode groove are aligned on the same line.

6. 6. The electrical resistance measuring device according to claim 5, An electrical resistance measuring device, wherein the dimension of the lower electrode in the lateral direction when viewed from above is larger than the dimension of the upper electrode in the lateral direction when viewed from above.

7. 2. The electrical resistance measuring device according to claim 1, The current application portion and the current extraction portion of the pair of upper and lower electrodes are arranged on opposite sides in the longitudinal direction when viewed from above.

8. 2. The electrical resistance measuring device according to claim 1, a base on which the lower electrode is placed; a load transfer member that transfers a load to the upper electrode in a direction toward the pedestal, An electrical resistance measuring device, wherein an elastic member is interposed at least either between the upper electrode and the load transmitting member or between the lower electrode and the base.

Images