Electromagnetic flowmeter

Abstract

To suppress the occurrence of poor welding at a butt portion on the circumference of a case.SOLUTION: An electromagnetic flowmeter includes a measuring tube through which fluid flows, a pair of wall portions arranged on an outer peripheral surface of the measuring tube at a predetermined interval in the axial direction of the measuring tube and protruding radially outward from the measuring tube, a sensor component placed between the pair of wall portions on the outer peripheral surface of the measuring tube, and a covering member that abuts against a top surface of one end that is located radially outward of two radial ends of the pair of wall portions and covers the sensor component along the outer peripheral surface of the measuring tube. The pair of wall portions have, axially inward from the top surface, a step portion including a first abutment surface abutting against a lower surface of a joggle provided at a butt portion on the circumference of the peripheral wall of the covering member and a second abutment surface abutting against an axial side surface of the joggle.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to an electromagnetic flowmeter. [Background technology]

[0002] In an electromagnetic flowmeter, sensor components are mounted on the outer circumferential surface of a measuring tube through which the fluid to be measured flows. For example, sensor components such as an excitation coil that generates a magnetic field in a direction perpendicular to the direction of the fluid flowing through the measuring tube and electrodes that extract electromotive forces generated by the passage of a conductive fluid are attached to the outer circumferential surface of the measuring tube.

[0003] A cylindrical case that covers the sensor components is wound around the outer periphery of the measuring tube from the side that protects these sensor components. The butt joint on the circumference of such a case has a joggle structure to absorb the tolerance of the arc length of the case. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2015-105929 A [Patent Document 2] JP 2016-095279 A [Patent Document 3] Japanese Patent Application Publication No. 11-339737 Summary of the Invention [Problem to be solved by the invention]

[0005] However, at the circumferential butt portion of the case, a gap is generated due to the tolerance in the width direction of the joggle, which may result in poor welding.

[0006] The present application is intended to solve such problems, and has an object to suppress the occurrence of welding defects at the circumferential butt joints of the case. [Means for solving the problem]

[0007] The electromagnetic flowmeter according to the present application comprises a measuring tube through which a fluid flows, a pair of wall portions arranged on an outer circumferential surface of the measuring tube at a predetermined interval in the axial direction of the measuring tube and protruding radially outward of the measuring tube, a sensor component placed between the pair of wall portions on the outer circumferential surface of the measuring tube, and a covering member that abuts against a top surface of an end portion located on the outer side in the radial direction of one of the two radial ends of the pair of wall portions and covers the sensor component along the outer circumferential surface of the measuring tube, the pair of wall portions having a step portion on the inside in the axial direction of the top surface, the step portion including a first abutment surface abutting against a lower surface of a joggle provided at a circumferential butt portion of a peripheral wall of the covering member and a second abutment surface abutting against a side surface of the joggle in the axial direction.

[0008] In the above-mentioned electromagnetic flowmeter, an overlap amount between the lower surface of the joggle and the first abutment surface may be set based on an axial tolerance of the joggle and a tolerance of the distance between the inner surfaces of the ends of the pair of wall portions.

[0009] In the above-mentioned electromagnetic flowmeter, the amount of overlap between the lower surface of the covering member and the top surfaces of the ends of the pair of wall portions may be set based on the axial tolerance of the covering member and the tolerance of the spacing between the second abutment surfaces of the pair of wall portions.

[0010] In the above-mentioned electromagnetic flowmeter, the distance between the side surface of the covering member and the outer surfaces of the ends of the pair of wall portions may be set based on the axial tolerance of the joggle and the tolerance of the distance between the outer surfaces of the ends of the pair of wall portions.

[0011] In the above-described electromagnetic flowmeter, the sensor components may include an excitation coil that generates a magnetic field in a direction perpendicular to the direction in which the fluid flows in the measuring tube, and electrodes that detect an electromotive force generated by the passage of the fluid. Effect of the Invention

[0012] According to the above-described electromagnetic flowmeter, the occurrence of poor welding at the circumferential butt joint portion of the case can be suppressed. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a perspective view showing the external configuration of an electromagnetic flowmeter. [Diagram 2] FIG. 2 is a perspective view showing the internal structure of the electromagnetic flowmeter. [Diagram 3] FIG. 3 is a schematic diagram showing a method of assembling a case according to the related art CA1. [Figure 4] FIG. 4 is a schematic diagram showing an example of reducing the width of the case. [Diagram 5] FIG. 5 is a diagram showing a gap at the circumferential butt joint of the cases. [Figure 6] FIG. 6 is a side view showing a pipe connection port of the electromagnetic flowmeter. [Figure 7] FIG. 7 is a cross-sectional view of the electromagnetic flowmeter taken along the line AA. [Figure 8] FIG. 8 is a schematic diagram showing the dimensions of each member around the case. [Figure 9] FIG. 9 is a diagram showing an example of setting the dimensions of each member around the case. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of an electromagnetic flowmeter according to the present application (hereinafter, referred to as an "embodiment") will be described with reference to the accompanying drawings.

[0015] <Overall composition> Fig. 1 is a perspective view showing the external configuration of an electromagnetic flowmeter 1. The electromagnetic flowmeter 1 shown in Fig. 1 utilizes Faraday's electromagnetic induction phenomenon to measure a flow rate based on an electromotive force generated by the flow of a conductive fluid passing through a magnetic field.

[0016] The electromagnetic flowmeter 1 can be installed at any point in the path of a pipe (not shown) through which the fluid to be measured flows. For example, in a flange-type electromagnetic flowmeter 1, flanges 3 formed on the outer periphery at both ends of a measuring pipe 2 are fastened to a flange (not shown) on the pipe side via fastening parts such as bolts and nuts, thereby connecting the electromagnetic flowmeter 1 to the pipe.

[0017] In such an electromagnetic flowmeter 1, various sensor components are mounted on the outer circumferential surface of the pipe-shaped measuring tube 2. For example, sensor components such as an excitation coil that generates a magnetic field in a direction perpendicular to the direction in which the fluid flows inside the measuring tube 2 and electrodes that detect electromotive forces generated by the passage of a conductive fluid are attached to the outer circumferential surface of the measuring tube 2.

[0018] A cylindrical case 10 that covers the sensor components is wrapped around the outer circumferential surface of the measuring tube 2 from the side that protects these sensor components. For example, as shown by the thick dashed line in Fig. 1, the side end portion of the case 10 is circumferentially welded, and as shown by the thick solid line in Fig. 1, the circumferential butt portion of the case 10 is linearly welded. Hereinafter, the former welding may be referred to as "circumferential welding" and the latter welding may be referred to as "linear welding". Such a circumferential butt portion of the case 10 has a joggle structure to accommodate the tolerance of the arc length of the case 10.

[0019] Fig. 2 is a perspective view showing the internal structure of the electromagnetic flowmeter 1. Fig. 2 shows the internal structure of the electromagnetic flowmeter 1 with a portion of the measuring tube 2 and the case 10 cut away. As shown in Fig. 2, the sensor components mounted on the outer peripheral surface of the measuring tube 2 are sealed by an internal space 7 surrounded by the outer peripheral surface of the measuring tube 2, the inner surface (opposite side to the flange 3) of the ring-shaped plate 5, and the inner peripheral surface of the case 10. By ensuring such an internal space 7, it is possible to suppress the intrusion of moisture and water from the outside of the case 10.

[0020] <Case assembly structure transition> <Related Technology CA1> Next, a description will be given of the transition of the structure in which the case 10 is assembled to the outer circumferential surface of the measuring pipe 2. Here, after explaining Related Art CA1 as an example of an assembly structure of the case 10, Related Art CA2, which is an improvement of Related Art CA1, will be described.

[0021] Fig. 3 is a schematic diagram showing a method of assembling a case according to related art CA1. As shown in Fig. 3, in related art CA1, the inner surfaces of flanges 3 formed on both ends of a measuring tube 2 are recessed to form annular grooves 3a.

[0022] The side edge of the ring-shaped flange 6, which is formed by curving a strip by rolling, is fitted into the annular groove 3a formed on the inner surface of the flange 3. The portion of the ring-shaped flange 6 thus fitted into the annular groove 3a of the flange 3 that is connected to the inner surface of the flange 3 and exposed to the outside is welded to form a welded portion 8.

[0023] Furthermore, a support surface 6a for supporting a side end of the case 10a is machined on the top surface of the ring-shaped flange 6. The side end of the case 10a placed on such a support surface 6a is welded, whereby the case 10a is wound around the outer circumferential surface of the measurement tube 2.

[0024] <Related Technology CA1 Issues> According to such related art CA1, the cost of the case 10a increases because the dimension in the width direction of the case 10a, i.e., in the axial direction (Z-axis direction) of the measuring pipe 2, needs to be the same as the distance between the flanges 3 formed on both ends of the measuring pipe 2. In addition, the weight of the electromagnetic flowmeter 1 increases as the width dimension of the case 10a increases.

[0025] These increases in cost and weight become more pronounced as the diameter of the measurement pipe 2 increases, since the width dimension of the case 10a must also increase as the diameter of the measurement pipe 2 increases, such as from medium diameter to large diameter.

[0026] <Related Technology CA2> An example of an improvement to Related Art CA1 is Related Art CA2, which reduces the width of the case 10. Fig. 4 is a schematic diagram showing an example of reducing the width of the case 10. As shown in Fig. 4, in Related Art CA1, an internal space 7-1 is secured by having a side end of the case 10a supported by a ring-shaped flange 6 fitted into an annular groove 3a of a flange 3. On the other hand, in Related Art CA2, an internal space 7-2 is secured by having a pair of ring-shaped plates 5 support the side ends of the case 10.

[0027] Thus, in related art CA1, the width dimension of the case 10a is equivalent to the spacing between the flanges 3, while in related art CA2, the width dimension of the case 10 is reduced to the spacing between the ring-shaped plates 5.

[0028] <Issues regarding related technology CA2> However, in the related art CA2 described above, a gap occurs at the butted portion on the circumference of the case 10 due to the tolerance in the width direction of the joggle, which may result in poor welding.

[0029] Fig. 5 is a diagram showing a gap at the butt joint on the circumference of the case 10. Fig. 5 shows an enlarged view 21 in which the range corresponding to the dashed frame in the related art CA2 is enlarged. Furthermore, Fig. 5 shows a see-through view 22 in which the filled-in part of the case 10 included in the enlarged view 21 is shown in a see-through state in order to improve the visibility of the joggle 11.

[0030] 5, a joggle 11 is provided at the butted portion on the circumference of the case 10 to absorb the tolerance of the arc length of the case 10. That is, the two ends E1 and E2 that are the butted portion on the circumference of the case 10 do not necessarily join because a tolerance occurs in the arc length of the case 10. For this reason, a stepped surface that extends from one end E1 of the butted portion on the circumference of the case 10 and extends in close contact with the underside of the other end E2 is formed as the joggle 11.

[0031] By engaging end portion E2 of such a joggle 11, even if an excess or deficiency occurs due to variation in the arc length of case 10, the butt portions on the circumference of case 10 can be joined, so that the tolerance of the arc length of case 10 can be absorbed.

[0032] On the other hand, in the above-mentioned related technology CA2, due to the influence of tolerances that occur in the width direction of the joggle 11, i.e., in the axial direction (Z direction) of the measuring tube 2, it is difficult to match the spacing between the pair of ring-shaped plates 5 with the width dimension of the joggle 11.

[0033] If the distance between the pair of ring-shaped plates 5 and the width of the joggle 11 do not match, the difference in the distance between the pair of ring-shaped plates 5 and the width of the joggle 11 appears as a gap G1.

[0034] If an attempt is made to weld the circumferential butt portion of case 10 while ignoring gap G1, that is, to perform linear welding (welding the thick solid line portion in FIG. 1), the melted portion will fall into gap G1, causing a poor weld. In the worst case scenario, an incomplete weld (hole) may occur in the circumferential butt portion of case 10.

[0035] Furthermore, the gap G1 allows high heat generated during welding to propagate to the internal space 7-2, which may adversely affect the sensor components mounted in the internal space 7-2. In the worst case, the sensor components may be damaged.

[0036] The problem in the related technique CA2 is caused in part by the fact that the gap G1 and the distance to the sensor components are shortened as the width of the case 10 is reduced. That is, in the related technique CA1, the side end of the case 10a is supported near the pair of flanges 3, so that even if a gap occurs, the distance to the sensor components is longer than in the related technique CA2. Therefore, in the related technique CA1, the linear welding of the butt portion on the circumference of the case 10a has a small effect on the sensor components. On the other hand, in the related technique CA2, the side end of the case 10 is supported by the ring-shaped plate 5 located closer to the center than the flanges 3, so that the distance from the gap G1 to the sensor components is shorter than in the related technique CA1. Therefore, in the related technique CA2, the linear welding of the butt portion on the circumference of the case 10 has a large effect on the sensor components.

[0037] <Problem-solving approach> <Step structure of ring-shaped plate 5> Therefore, in the electromagnetic flowmeter 1 of this embodiment, a pair of ring-shaped plates 5 that are attached facing each other to the outer peripheral surface of the measuring tube 2 have a step structure including a first surface that abuts against the underside of the joggle 11 and a second surface that abuts against the side surface of the joggle 11.

[0038] Fig. 6 is a side view showing a pipe connection port of the electromagnetic flowmeter 1. Fig. 6 shows the cylindrical case 10 and the joggle 11 formed at the butt portion on the circumference of the case 10, with part of the flange 3 in a see-through state, from a side view that enhances the visibility of the joggle 11.

[0039] Thus, a cross-sectional view taken along the line AA in Fig. 6 is shown in Fig. 7. Fig. 7 is a cross-sectional view taken along the line AA of the electromagnetic flowmeter 1. Fig. 7 shows an enlarged view 31 and an enlarged view 32 of the range corresponding to the frame indicated by the dashed line in the cross-sectional view shown in the same figure.

[0040] Here, from the perspective of comparing the above-mentioned related art CA2 with this embodiment, enlarged figure 31 shows the peripheral structure of a joggle related to the above-mentioned related art CA2, while enlarged figure 32 shows the peripheral structure of a joggle related to this embodiment.

[0041] For example, in the above-mentioned related art CA1, as shown in an enlarged view 31 in Fig. 7, the dimensional deviation of the distance between the pair of ring-shaped plates 5 and the width of the joggle 11 appears as a gap G1. Such gap G1 becomes a space (hole) penetrating the case 10 and communicating the inside and outside of the case 10. For this reason, the gap G1 can be a path through which the heat generated during linear welding, in addition to the parts melted during linear welding (welding of the thick solid line part in Fig. 1), such as the base material, welding rod, and filler metal, penetrates into the inside of the case 10.

[0042] On the other hand, in this embodiment, as shown in the enlarged view 32 in FIG. 7, a step portion 50 including a first surface 51 abutting the lower surface of the joggle 11 and a second surface 52 abutting the side surface of the joggle 11 in the axial direction (Z-axis direction) is formed on the ring-shaped plate 5.

[0043] For this reason, even in this embodiment, a gap G2 may occur between the side end of the joggle 11 and the second surface 52, but the lower surface of the joggle 11 and the first surface 51 come into contact with each other, blocking the path of infiltration into the inside of the case 10. This makes it possible to prevent the melted portion from infiltrating into the inside of the case 10 during linear welding, or to prevent the heat generated during linear welding from propagating into the inside of the case 10.

[0044] At this time, the shorter the distance between the first surface 51 and the lower surface of the joggle 11, the higher the effect of blocking heat and the like, but the first surface 51 and the lower surface of the joggle 11 do not necessarily have to be in close contact with each other. This is because the infiltration path into the inside of the case 10 is not a straight path from the gap G2 due to the step portion 50 according to this embodiment. That is, the infiltration path into the inside of the case 10 is an L-shaped path including a portion formed by the side surface of the joggle 11 and the second surface 52, and a portion formed by the lower surface of the joggle 11 and the first surface 51. For this reason, even if the first surface 51 and the lower surface of the joggle 11 do not necessarily have to be in close contact with each other, a sufficient blocking effect can be obtained at the bent portion of the L-shaped path.

[0045] In this way, the electromagnetic flowmeter 1 according to this embodiment prevents the melted portion from penetrating into the case 10 during linear welding, thereby preventing poor welding at the circumferential butt joint of the case 10. In addition, the electromagnetic flowmeter 1 according to this embodiment prevents the heat generated during linear welding from propagating into the case 10, thereby preventing damage to the sensor components.

[0046] <Dimensions of each part around the case> Next, the dimensions of each member around the case 10 will be described. Fig. 8 is a schematic diagram showing the dimensions of each member around the case 10. Fig. 8 shows an enlarged schematic diagram of the range corresponding to the frame shown by the dashed line in the cross-sectional view shown in Fig. 7, i.e., the right side of the case 10 shown in Fig. 7.

[0047] <Dimension d1> The gap (dimension d1 in FIG. 8) between the side surface of the joggle 11 and the second surface 52 is set to a nominal value, a so-called nominal dimension, such that the joggle 11 and the ring-shaped plate 5 do not interfere with each other when assembled. As merely one example, the nominal value of the dimension d1 can be set based on the tolerance of the joggle 11 in the width direction (Z direction) and the tolerance of the distance between the pair of second surfaces 52 on both the left and right sides.

[0048] <dimension d2> The amount of overlap between the underside of the joggle 11 and the first surface 51 (dimension d2 in FIG. 8) is set to a nominal value that can provide a blocking effect for heat propagating from the gap G2 that occurs at the butt joint on the circumference of the case 10, even if the actual dimensions of each component vary within the tolerance range.

[0049] In order to obtain such a heat blocking effect, the dimension d2 is set to a nominal value such that the actual dimension of the dimension d2 is equal to or greater than a threshold value Th1, for example 0.7 mm, based on the widthwise tolerance of the joggle 11 and the tolerance of the spacing between the inner surfaces 5a of the pair of ring-shaped plates 5 on both the left and right sides.

[0050] <dimension d3> The amount of overlap between the bottom surface of the case 10 and the top surface 5b of the ring-shaped plate 5 (dimension d3 in Figure 8) is set to a nominal value that can prevent gaps from occurring on the circumference of the case 10 even if the actual dimensions of each component vary within the tolerance range.

[0051] That is, the width of the case 10 in the axial direction (Z-axis direction) is not constant on the circumference of the case 10 because of the tolerance. Therefore, if the lap amount of the dimension d3 is set while ignoring the tolerance in the width direction of the case 10, the width of the case 10 is not full to the interval of the inner surface 5a of the ring-shaped plate 5, and a gap is generated in the portion where the side end of the case 10 does not reach the top surface 5b of the ring-shaped plate 5. In order to suppress the occurrence of a gap on the circumference of the case 10 in this way and thereby suppress the propagation of heat into the case 10 during circumferential welding (welding of the thick dashed line portion shown in FIG. 1), the dimension d3 is set to a nominal value such that the actual dimension of the dimension d3 is equal to or greater than the threshold value Th2, for example, 2.4 mm. The nominal value of the dimension d3 is merely an example and can be set based on the tolerance in the width direction of the case 10 and the tolerance of the interval between the pair of second surfaces 52 on both the left and right sides.

[0052] <dimension d4> The distance (dimension d4 in FIG. 8) between the side surface of the case 10 and the outer surface 5c of the ring-shaped plate 5 is set to a nominal value that ensures enough space to realize automation of circumferential welding of the case 10 (welding of the thick dashed line portion shown in FIG. 1) even if the actual dimensions of each component vary within the tolerance range.

[0053] For example, to realize the circumferential welding of the case 10 by automated welding (MIG welding), it is preferable to secure a space large enough to prevent the molten material from leaking onto the outer surface 5c of the ring-shaped plate 5 during welding. From this perspective, the nominal value of the dimension d4 can be set based on the tolerance in the width direction of the case 10 and the tolerance of the distance between the outer surfaces 5c of the pair of ring-shaped plates 5 on both the left and right sides.

[0054] <Dimension setting example> Fig. 9 is a diagram showing an example of setting the dimensions of each component around the case 10. Fig. 9 shows an example of setting the dimensions of each component in an electromagnetic flowmeter 1 equipped with a large-diameter measuring tube 2, and provides an explanation of the dimensions, nominal value, tolerance, average value, maximum value, minimum value, etc. for each component.

[0055] Here, the example of dimension settings shown in Figure 9 is advantageous in that dimensions d1 to d4 satisfy the requirements described below in an electromagnetic flowmeter in which the tolerances of the width of the case 10, the arc length of the case 10, the spacing between a pair of ring-shaped plates 5, and the like increase as the diameter of the measuring tube 2 increases.

[0056] As one aspect, by setting the nominal value of the dimension d1 to 1 mm, even if the dimension d1 is the minimum allowable dimension, it is 0.1 mm. From this, it is clear that the nominal value of the dimension d1 is set so that the joggle 11 and the ring-shaped plate 5 do not interfere with each other during assembly.

[0057] As another aspect, by setting the nominal value of the dimension d2 to 1.5 mm, even if the dimension d2 is the minimum allowable dimension, it is 0.7 mm. Therefore, it is clear that the nominal value of the dimension d2 is set to ensure an overlap amount equal to or greater than the threshold value Th1. As a result, even if the dimensional tolerance of each component is large, it is possible to obtain an effect of blocking heat propagating from the gap G2 that occurs at the butt joint on the circumference of the case 10.

[0058] As another aspect, by setting the nominal value of the dimension d3 to 3 mm, even if the dimension d3 is the minimum allowable dimension, it is 2.4 mm. Therefore, it is clear that the nominal value of the dimension d3 is set to ensure an overlap amount equal to or greater than the threshold value Th2. This makes it possible to prevent gaps from occurring around the circumference of the case 10 even if the dimensional tolerances of the various components are large.

[0059] As another aspect, by setting the nominal value of dimension d4 to 4.5 mm, even if dimension d4 is the minimum allowable dimension, it is 3.9 mm. Therefore, it is clear that the nominal value of dimension d4 is set to ensure a space equal to or greater than 4 mm, which is the guideline for the width of the space that allows automatic welding to be realized. This allows the circumferential welding of case 10 to be realized by automated welding (MIG welding).

[0060] The above-described embodiment is merely an example, and various applications are possible.

[0061] For example, in the above embodiment, a flange-type electromagnetic flowmeter 1 is exemplified, but the form of the pipe connection is not limited to the flange type, and the above-mentioned step structure may be realized by other pipe connections, for example, wafer type. Furthermore, in the above embodiment, an electromagnetic flowmeter 1 is exemplified in which a detection unit that generates a magnetic field in a measurement tube through which a fluid passes and detects an electromotive force generated by the passage of the fluid and a conversion unit that converts the electromotive force detected by the detection unit into a flow rate of the fluid are integrated, but this is not limited. For example, the above-mentioned step structure may be realized in a separated type electromagnetic flowmeter in which the detection unit and the conversion unit are separated. [Explanation of symbols]

[0062] 1 Electromagnetic flowmeter 2 Measuring tube 3 Flange 5 Ring Plate 5a Inside surface 5b Top 5c External surface 50 Step 51 First Side 52 Second Side 7. Interior Space 10 Cases 11 Joggle

Claims

1. A measuring tube through which a fluid flows; a pair of wall portions disposed on an outer peripheral surface of the measurement tube at a predetermined interval in an axial direction of the measurement tube and protruding toward an outer side in a radial direction of the measurement tube; a sensor component placed between the pair of wall portions on an outer circumferential surface of the measuring tube; a cover member that abuts against a top surface of an end portion located on the outer side in the radial direction out of two ends of the pair of wall portions in the radial direction and covers the sensor component along an outer circumferential surface of the measuring tube, the pair of wall portions have a step portion located more inward in the axial direction than the top surface, the step portion including a first abutment surface that abuts against a lower surface of a joggle provided at a circumferential butt portion of the peripheral wall of the cover member, and a second abutment surface that abuts against a side surface of the joggle in the axial direction.

2. 2. The electromagnetic flowmeter according to claim 1, wherein an overlap amount between the lower surface of the joggle and the first abutment surface is set based on an axial tolerance of the joggle and a tolerance of a distance between inner surfaces of the ends of the pair of wall portions.

3. 2. The electromagnetic flowmeter according to claim 1, wherein an overlap amount between the bottom surface of the covering member and the top surfaces of the ends of the pair of wall portions is set based on an axial tolerance of the covering member and a tolerance of a gap between the second abutment surfaces of the pair of wall portions.

4. 2. The electromagnetic flowmeter according to claim 1, wherein a distance between the side surface of the cover member and the outer surfaces of the ends of the pair of wall portions is set based on an axial tolerance of the joggle and a tolerance of the distance between the outer surfaces of the ends of the pair of wall portions.

5. 5. The electromagnetic flowmeter according to claim 1, wherein the sensor components include an excitation coil that generates a magnetic field in a direction perpendicular to the direction in which the fluid flows in the measuring tube, and electrodes that detect an electromotive force generated by the passage of the fluid.

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