Electromagnetic flowmeter

Abstract

The invention provides an electromagnetic flow meter which can inhibit poor welding of butt joint parts on the circumference of a housing. An electromagnetic flowmeter comprises: a measurement tube through which a fluid flows; a pair of wall portions disposed on the outer peripheral surface of the measurement tube at a predetermined interval in the axial direction of the measurement tube and protruding toward the outside in the radial direction of the measurement tube; a sensor component placed between the pair of wall portions on the outer peripheral surface of the measurement tube; and a cover member that comes into contact with the top surface of the end portion located on the outside in the radial direction of the two end portions in the radial direction of the pair of wall portions, and that covers the sensor component along the outer peripheral surface of the measurement tube, the pair of wall portions having a step portion on the inside in the axial direction than the top surface. The step part comprises a first abutting surface and a second abutting surface, wherein the first abutting surface abuts against the lower surface of a meshing buckle of a butt joint part arranged on the circumference of the peripheral wall of the covering component, and the second abutting surface abuts against the axial side face of the meshing buckle.

Description

Technical Field

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

[0002] In an electromagnetic flowmeter, sensor components are mounted on the outer circumference 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 fluid flow in the measuring tube or an electrode that extracts the electromotive force generated by the passage of a conductive fluid are assembled on the outer circumference of the measuring tube.

[0003] In order to protect these sensor components, a cylindrical housing covering the sensor components is wound around the outer circumference of the measuring tube. The butt joint portion on the circumference of the housing is formed into a joggle structure to absorb the tolerance of the arc length of the housing.

[0004] [Prior art literature]

[0005] [Patent Document]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2015-105929

[0007] [Patent Document 2] Japanese Patent Application Publication No. 2016-095279

[0008] [Patent Document 3] Japanese Patent Application Laid-Open No. 11-339737 Summary of the invention

[0009] [Problems to be solved by the invention]

[0010] However, a gap is generated in the butted portion on the circumference of the housing due to tolerance in the width direction of the engagement buckle, which may cause welding failure.

[0011] The present application is to solve such a problem, and an object of the present application is to suppress the occurrence of welding defects at the butted portions on the circumference of a housing.

[0012] [Technical means to solve the problem]

[0013] The electromagnetic flowmeter of the present application comprises: a measuring tube for fluid flow; a pair of wall portions, which are arranged on the outer peripheral surface of the measuring tube at a predetermined interval in the axial direction of the measuring tube and protrude toward the radial outer side of the measuring tube; a sensor part, which is placed on the outer peripheral surface of the measuring tube between the pair of wall portions; and a covering member, which abuts against the top surface of the end portion located on the radial outer side of the two radial ends of the pair of wall portions and covers the sensor part along the outer peripheral surface of the measuring tube, the pair of wall portions having a step difference portion at a position closer to the inner side of the axial direction than the top surface, and the step difference portion includes a first abutment surface abutting against the lower surface of the meshing buckle of the docking portion arranged on the circumference of the peripheral wall of the covering member, and a second abutment surface abutting against the axial side surface of the meshing buckle.

[0014] In the electromagnetic flowmeter, the overlap amount of the lower surface of the engagement buckle and the first contact surface may be set based on the tolerance of the engagement buckle in the axial direction and the tolerance of the interval between the inner surfaces of the ends of the pair of wall portions.

[0015] In the electromagnetic flowmeter, the overlap amount between the lower surface of the covering member and the top surface of the end of the pair of wall portions can be set based on the axial tolerance of the covering member and the tolerance of the interval between the second abutting surfaces of the pair of wall portions.

[0016] In the electromagnetic flowmeter, the interval between the side surface of the covering member and the outer side surface of the end portions of the pair of wall portions may be set based on the axial tolerance of the engagement buckle and the tolerance of the interval between the outer side surfaces of the end portions of the pair of wall portions.

[0017] In the electromagnetic flowmeter, the sensor component may include an exciting coil for generating a magnetic field in a direction perpendicular to a direction in which the fluid flows in the measuring tube, and an electrode for detecting an electromotive force generated by passage of the fluid.

[0018] [Effects of the Invention]

[0019] According to the electromagnetic flowmeter, it is possible to suppress the occurrence of welding defects at the butted portions on the circumference of the casing. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a perspective view showing the appearance structure of an electromagnetic flowmeter.

[0021] Figure 2 This is a perspective view showing the internal structure of the electromagnetic flowmeter.

[0022] Figure 3 1 is a schematic diagram showing a method of assembling a housing of the related art CA1.

[0023] Figure 4 It is a schematic diagram showing an example of reducing the width of the casing.

[0024] Figure 5 It is a diagram showing the gap between the butted parts on the circumference of the shell.

[0025] Figure 6 This is a side view showing the pipe connection port of the electromagnetic flowmeter.

[0026] Figure 7 This is a cross-sectional view of the electromagnetic flowmeter along the AA arrow line.

[0027] Figure 8 It is a schematic diagram showing the dimensions of each member around the housing.

[0028] Fig. 9 It is a diagram showing an example of setting the dimensions of each member around the casing.

[0029] [Explanation of Symbols]

[0030] 1: Electromagnetic flow meter

[0031] 2: Determination tube

[0032] 3: Flange

[0033] 5: Ring plate

[0034] 5a: Inside side

[0035] 5b: Top

[0036] 5c: Outer side

[0037] 50: Step difference

[0038] 51: Side 1

[0039] 52: Side 2

[0040] 7: Internal Space

[0041] 10: Shell

[0042] 11: Engagement buckle DETAILED DESCRIPTION

[0043] Hereinafter, an embodiment of the electromagnetic flowmeter of the present application (hereinafter referred to as “embodiment”) will be described with reference to the accompanying drawings.

[0044] <Overall structure>

[0045] Figure 1 It is a perspective view showing the external appearance structure of the electromagnetic flowmeter 1. Figure 1The electromagnetic flowmeter 1 shown utilizes Faraday's electromagnetic induction phenomenon to measure a flow rate based on an electromotive force generated by a conductive fluid flowing in a magnetic field.

[0046] The electromagnetic flowmeter 1 can be installed at any point in the path of a pipe (not shown) through which a fluid to be measured flows. For example, in a flange-shaped electromagnetic flowmeter 1, flanges 3 formed on the outer periphery of both ends of a measuring tube 2 are fastened to flanges (not shown) on the pipe side via fastening parts such as bolts or nuts, thereby connecting the electromagnetic flowmeter 1 to the pipe.

[0047] In this electromagnetic flowmeter 1, various sensor components are mounted on the outer peripheral surface of the measuring tube 2 formed into a tubular shape. For example, sensor components such as an excitation coil that generates a magnetic field in a direction perpendicular to the direction of fluid flow in the measuring tube 2 or electrodes that detect an electromotive force generated by the passage of a conductive fluid are assembled on the outer peripheral surface of the measuring tube 2.

[0048] In order to protect these sensor components, a cylindrical housing 10 covering the sensor components is wound around the outer circumference of the measuring tube 2. Figure 1 As shown by the thick dashed line, the side end portion of the housing 10 is welded into a circumferential shape, and as shown in FIG. Figure 1 As shown by the thick solid line, the butted portion on the circumference of the housing 10 is welded into a straight line. Hereinafter, the former welding may be referred to as "circumferential welding" and the latter welding may be referred to as "straight welding". The butted portion on the circumference of the housing 10 is formed into a meshing buckle structure in order to absorb the tolerance of the arc length of the housing 10.

[0049] Figure 2 1 is a perspective view showing the internal structure of the electromagnetic flowmeter 1. Figure 2 FIG. 2 shows the internal structure of the electromagnetic flowmeter 1 in a state where a portion of the measuring tube 2 and the housing 10 are cut away. Figure 2 As shown, the sensor parts mounted on the outer peripheral surface of the measuring tube 2 are sealed by the inner space 7 surrounded by the outer peripheral surface of the measuring tube 2, the inner side surface of the annular plate 5 (the opposite side of the flange 3), and the inner peripheral surface of the housing 10. By ensuring such an inner space 7, the intrusion of moisture or water from the outside of the housing 10 can be suppressed.

[0050] <Transition of the housing assembly structure>

[0051] <Related Technology CA1>

[0052] Next, the transition of the structure in which the housing 10 is assembled to the outer peripheral surface of the measuring tube 2 will be described. Here, as an example of the assembled structure of the housing 10, after the related art CA1 is described, the related art CA2 which is an improvement of the related art CA1 will be described.

[0053] Figure 3 Schematic diagram showing the assembly method of the housing of the related art CA1. Figure 3 As shown, in the related art CA1, the inner side surfaces of the flanges 3 formed at both ends of the measuring tube 2 are recessed, thereby forming annular grooves 3a.

[0054] The side edge of the annular flange portion 6 formed by bending the strip plate by roller processing is fitted into the annular groove 3a formed on the inner side surface of the flange 3. In this way, the portion of the annular flange portion 6 fitted into the annular groove 3a of the flange 3 that is connected to the inner side surface of the flange 3 and exposed to the outside is welded, thereby forming a welded portion 8.

[0055] Furthermore, a support surface 6a for supporting the side end of the housing 10a is machined on the top surface of the annular flange 6. The side end of the housing 10a placed on the support surface 6a is welded, and the housing 10a is wound along the outer peripheral surface of the measuring tube 2.

[0056] <Related Technology CA1 Issues>

[0057] According to the related art CA1, the dimension of the housing 10a in the width direction, that is, in the axial direction (Z-axis direction) of the measuring tube 2, needs to be set to the same dimension as the interval between the flanges 3 formed at both ends of the measuring tube 2, so the cost of the housing 10a becomes high. In addition, as the width of the housing 10a increases, the weight of the electromagnetic flowmeter 1 also increases.

[0058] These cost and weight increases become more significant as the diameter of the measuring tube 2 increases, such as when the diameter of the measuring tube 2 is medium or large, because the width of the housing 10a also needs to increase.

[0059] <Related Technology CA2>

[0060] As an improvement of the related art CA1, there is a related art CA2 in which the width of the housing 10 is reduced. Figure 4 1 is a schematic diagram showing an example of reducing the width of the housing 10. Figure 4 As shown, in the related art CA1, the inner space 7-1 is ensured by supporting the side ends of the housing 10a on the annular flange portion 6 embedded in the annular groove 3a of the flange 3. On the other hand, in the related art CA2, the inner space 7-2 is ensured by supporting the side ends of the housing 10 on a pair of annular plates 5.

[0061] Thus, in the related art CA1, the width dimension of the housing 10 a is equal to the interval between the flanges 3 , whereas in the related art CA2, the width dimension of the housing 10 a is reduced to the interval between the annular plates 5 .

[0062] <Related Technology CA2 Issues>

[0063] However, in the related art CA2, a gap is generated in the butted portion on the circumference of the housing 10 due to a tolerance in the width direction of the engagement buckle, which sometimes causes welding failure.

[0064] Figure 5 1 is a diagram showing the gap between the butted parts on the circumference of the housing 10. Figure 5 FIG. 21 shows an enlarged view of the range corresponding to the dotted line frame in the related art CA2. Figure 5 In order to improve the visibility of the engaging buckle 11, a transparent view 22 is shown which shows the shielded portion of the housing 10 included in the enlarged view 21 in a transparent state.

[0065] like Figure 5 As shown in the figure, the mating part on the circumference of the housing 10 is provided with an engagement buckle 11 in order to absorb the tolerance of the arc length of the housing 10. That is, the two ends E1 and E2 as the mating part on the circumference of the housing 10 are not necessarily engaged due to the tolerance in the arc length of the housing 10. Therefore, a step surface extending from one of the ends E1 of the mating part on the circumference of the housing 10 and extending in a state of close contact with the lower side surface of the other end E2 is formed as the engagement buckle 11.

[0066] By locking the end E2 with this engagement buckle 11, even if the length of the arc of the shell 10 is too much or too little due to deviation, the butt joint parts on the circumference of the shell 10 can be joined, thereby absorbing the tolerance of the length of the arc of the shell 10.

[0067] On the other hand, in the related art CA2, due to the influence of tolerance in the width direction of the engagement buckle 11, that is, in the axial direction (Z direction) of the measuring tube 2, it is difficult to make the distance between the pair of annular plates 5 and the width of the engagement buckle 11 consistent with each other.

[0068] Furthermore, when the distance between the pair of annular plates 5 and the width of the meshing buckle 11 do not match, the deviation between the distance between the pair of annular plates 5 and the width of the meshing buckle 11 appears as a gap G1 .

[0069] If the gap G1 is ignored and welding of the butted parts on the circumference of the housing 10 is performed, that is, linear welding ( Figure 1In the worst case, there is a concern that an incomplete weld (hole) may be generated at the butt joint portion on the circumference of the housing 10.

[0070] Furthermore, the gap G1 allows high heat generated during welding to propagate into the internal space 7 - 2 , which may adversely affect sensor components mounted in the internal space 7 - 2 . In the worst case, there is a concern that the sensor components may be damaged.

[0071] The problem of this related art CA2 is that the distance between the gap G1 and the sensor part is reduced as the width of the housing 10 is reduced. That is, in the related art CA1, the side ends of the housing 10a are supported near a pair of flanges 3, so even if a gap is generated, the distance to the sensor part is longer than that of the related art CA2. Therefore, in the related art CA1, the linear welding of the butt joint portion on the circumference of the housing 10a has little effect on the sensor part. On the other hand, in the related art CA2, the side ends of the housing 10 are supported by the annular plate 5 located more centrally than the flange 3, so the distance from the gap G1 to the sensor part is shorter than that of the related art CA1. Therefore, in the related art CA2, the linear welding of the butt joint portion on the circumference of the housing 10 also has a great effect on the sensor part.

[0072] <Solution to the problem>

[0073] <Step structure of the annular plate 5>

[0074] Therefore, in the electromagnetic flowmeter 1 of this embodiment, the pair of annular plates 5 mounted on the outer peripheral surface of the measuring tube 2 in a mutually opposing state are configured as a stepped structure including a first surface abutting against the lower surface of the meshing buckle 11 and a second surface abutting against the side surface of the meshing buckle 11.

[0075] Figure 6 FIG. 1 is a side view showing a pipe connection port of the electromagnetic flowmeter 1. Figure 6 In order to improve the visibility of the engagement hook 11, a part of the flange 3 is made transparent to show the cylindrical housing 10 and the engagement hook 11 formed on the circumference of the housing 10.

[0076] So, Figure 6 The cross-sectional view of the AA arrow is shown in Figure 7 . Figure 7 AA is a cross-sectional view of the electromagnetic flowmeter 1. Figure 7 31 and 32 are enlarged views of the range corresponding to the frame indicated by the dotted line in the cross-sectional view shown in this figure.

[0077] Here, in order to explain the comparison between the related art CA2 and the present embodiment, the peripheral structure of the engagement buckle of the related art CA2 is shown in the enlarged view 31 , and the peripheral structure of the engagement buckle of the present embodiment is shown in the enlarged view 32 .

[0078] For example, in the related art CA2, Figure 7 As shown in the enlarged view 31, the gap G1 is a gap between the distance between the pair of annular plates 5 and the width of the meshing buckle 11. This gap G1 is a space (hole) that penetrates the housing 10 and connects the inside and outside of the housing 10. Therefore, the gap G1 is not only a linear weld ( Figure 1 In addition to the portion that melts during welding (the portion shown in the thick solid line), such as a portion of the base material, welding rod, filler material, etc., it is also possible that the heat generated during linear welding penetrates into the interior of the shell 10.

[0079] On the other hand, in this embodiment, if Figure 7 32 , the annular plate 5 is provided with a stepped portion 50 including a first surface 51 that contacts the lower surface of the engagement buckle 11 and a second surface 52 that contacts the side surface of the engagement buckle 11 in the axial direction (Z-axis direction).

[0080] Therefore, in the present embodiment, a gap G2 may be generated between the side end of the engagement buckle 11 and the second surface 52, but the lower surface of the engagement buckle 11 is in contact with the first surface 51, so the penetration path into the housing 10 is cut off. Therefore, it is possible to suppress the melted portion during linear welding from penetrating into the housing 10 or the heat generated during linear welding from propagating into the housing 10.

[0081] At this time, the shorter the distance between the first surface 51 and the lower surface of the meshing buckle 11, the higher the heat or other cutting effect. However, the first surface 51 does not necessarily need to be in close contact with the lower surface of the meshing buckle 11. This is because the immersion path into the inside of the housing 10 does not become a straight path from the gap G2 due to the step portion 50 of this embodiment. That is, the immersion path into the inside of the housing 10 becomes an L-shaped path, and the L-shaped path includes a portion formed by the side surface of the meshing buckle 11 and the second surface 52, and a portion formed by the lower surface of the meshing buckle 11 and the first surface 51. Therefore, even if the first surface 51 and the lower surface of the meshing buckle 11 are not necessarily in close contact, a sufficient cutting effect can be obtained by the curved portion of the L-shaped path.

[0082] Thus, according to the electromagnetic flowmeter 1 of this embodiment, the melted portion during linear welding is suppressed from penetrating into the housing 10, thereby suppressing the occurrence of welding defects at the butted portion on the circumference of the housing 10. In addition, according to the electromagnetic flowmeter 1 of this embodiment, the heat generated during linear welding is suppressed from propagating into the housing 10, thereby suppressing the damage of sensor parts.

[0083] <Dimensions of the components around the housing>

[0084] Next, the dimensions of each member around the housing 10 will be described. Figure 8 Schematic diagram showing the dimensions of the components around the housing 10. Figure 8 In Figure 7 The range corresponding to the frame indicated by the dotted line in the cross-sectional view shown, i.e. Figure 7 The right side of the housing 10 is shown enlarged and schematically.

[0085] <Size d1>

[0086] The gap between the side surface of the engaging buckle 11 and the second surface 52 ( Figure 8 The dimension d1) is used to set the nominal value of the meshing buckle 11 and the components of the annular plate 5 so that they do not interfere with each other during assembly, i.e., the so-called nominal dimension. The nominal value of the dimension d1 is only an example and can be set based on the tolerance of the width direction (Z direction) of the meshing buckle 11 and the tolerance of the interval between the second surfaces 52 forming a pair on the left and right sides.

[0087] <Size d2>

[0088] The overlap amount ( Figure 8 The dimension d2) is set to a nominal value of the effect of cutting off heat propagating from the gap G2 generated at the butting portion on the circumference of the housing 10, even if the actual dimensions of the components deviate within the tolerance range.

[0089] In order to obtain the thermal cutting effect in this way, the actual dimension of dimension d2 is set to a threshold value Th1, for example, a nominal value greater than 0.7 mm, based on the tolerance in the width direction of the engaging buckle 11 and the tolerance of the interval between the inner side surfaces 5a of the annular plates 5 forming a pair on the left and right sides.

[0090] <Size d3>

[0091] The overlap amount ( Figure 8 The dimension d3) is set to a nominal value that can suppress the occurrence of gaps on the circumference of the housing 10 even when the actual dimensions of the components deviate within the tolerance range.

[0092] That is, the width of the housing 10 in the axial direction (Z-axis direction) has a tolerance, so it is not constant on the circumference of the housing 10. Therefore, when the overlap amount of dimension d3 is set without considering the tolerance in the width direction of the housing 10, the width of the housing 10 is smaller than the interval between the inner side surfaces 5a of the annular plate 5, and a gap is generated in the portion where the side end of the housing 10 does not reach the top surface 5b of the annular plate 5. In this way, the generation of a gap on the circumference of the housing 10 is suppressed, thereby suppressing the occurrence of a gap in the circumference welding ( Figure 1 In terms of heat propagation into the housing 10 during welding (the thick dashed line portion shown in FIG. 1 ), the actual dimension of the dimension d3 is set to a threshold value Th2, for example, a nominal value of 2.4 mm or more. This nominal value of the dimension d3 is only an example and can be set based on the tolerance in the width direction of the housing 10 and the tolerance of the interval between the second surfaces 52 forming a pair on the left and right sides.

[0093] <Size d4>

[0094] The distance between the side surface of the housing 10 and the outer side surface 5c of the annular plate 5 ( Figure 8 The dimension d4) is set to ensure that the circumferential welding of the housing 10 can be achieved even if the actual dimensions of the components deviate within the tolerance range. Figure 1 The nominal value of the automated space for welding (the thick dotted line portion shown).

[0095] For example, in order to realize circumferential welding of the housing 10 by automated welding (Metal Inert Gas (MIG) welding), it is preferable to ensure a space to such an extent that the melted portion during welding does not leak to the outer side surface 5c of the annular plate 5. In this regard, the nominal value of the dimension d4 can be set based on the tolerance in the width direction of the housing 10 and the tolerance of the interval between the outer side surfaces 5c of the annular plates 5 forming a pair on the left and right sides.

[0096] <Size setting example>

[0097] Fig. 9 1 is a diagram showing an example of setting the dimensions of each member around the housing 10. Fig. 9 1 shows an example of setting the dimensions of each component in the electromagnetic flowmeter 1 equipped with the large-diameter measuring tube 2, and shows an explanation of the dimensional portion, the nominal value, the tolerance, the average value, the maximum value, the minimum value, etc. for each component.

[0098] Here, Fig. 9 The dimensional setting example shown is excellent in the following aspects: in an electromagnetic flowmeter where the tolerance of the width of the housing 10 or the arc length of the housing 10, the interval between a pair of annular plates 5, etc. increases as the diameter of the measuring tube 2 increases, dimensions d1 to d4 satisfy the necessary conditions described below.

[0099] On the one hand, by setting the nominal value of dimension d1 to 1 mm, even when dimension d1 is the minimum allowable dimension, it becomes 0.1 mm. This clearly shows that the nominal value of dimension d1 is set so that the members of the engaging buckle 11 and the annular plate 5 do not interfere with each other during assembly.

[0100] On the other hand, by setting the nominal value of dimension d2 to 1.5 mm, even when dimension d2 is the minimum allowable dimension, it becomes 0.7 mm. Therefore, it is clear that the nominal value of dimension d2 is set to ensure the overlap amount of the threshold value Th1 or more. Thus, even when the tolerance of the dimensions of the components is large, the effect of cutting off the heat propagating from the gap G2 generated in the butt joint portion on the circumference of the housing 10 can be obtained.

[0101] As another aspect, by setting the nominal value of dimension d3 to 3 mm, even when dimension d3 is the minimum allowable dimension, it becomes 2.4 mm. Therefore, it is clear that the nominal value of dimension d3 that can ensure the overlap amount of the threshold value Th2 or more is set. Thus, even when the tolerance of the dimensions of the components is large, the gap generated on the circumference of the housing 10 can be suppressed.

[0102] On the other hand, by setting the nominal value of dimension d4 to 4.5 mm, even when dimension d4 is the minimum allowable dimension, it becomes 3.9 mm. Therefore, it is clear that the nominal value of dimension d4 can be set to ensure a space equal to or larger than 4 mm, which is the reference width of the space that can achieve automatic welding. As a result, the circumferential welding of the shell 10 can be achieved by automated welding (MIG welding).

[0103] The above-described embodiment is merely an example, and various applications are possible.

[0104] For example, in the above embodiment, a flange-shaped electromagnetic flowmeter 1 is illustrated, but the form of the piping connection is not limited to the flange shape, and the step difference structure can also be realized by other piping connections, such as a wafer shape. Furthermore, in the above embodiment, an electromagnetic flowmeter 1 that generates a magnetic field in a measuring tube through which a fluid passes, a detection unit that 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 fluid flow rate is cited as an example, but it is not limited to this. For example, it does not prevent the step difference structure from being realized in a separate electromagnetic flowmeter in which the detection unit and the conversion unit are separated.

Claims

1. An electromagnetic flowmeter, characterized in that: have: a measuring tube for fluid flow; a pair of wall portions, arranged on the outer peripheral surface of the measuring tube at a predetermined interval in the axial direction of the measuring tube, and protruding toward the outer side in the radial direction of the measuring tube; A sensor component is placed on the outer peripheral surface of the measuring tube and between the pair of wall portions; as well as a covering member that contacts the top surface of the radially outer end portion 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 a step portion at a position further inward in the axial direction than the top surface, and the step portion includes a first abutting surface abutting against a lower surface of an engaging buckle of a docking portion arranged on the circumference of the peripheral wall of the covering member, and a second abutting surface abutting against a side surface of the engaging buckle in the axial direction.

2. The electromagnetic flowmeter according to claim 1, characterized in that: The overlap amount between the lower surface of the engagement buckle and the first contact surface is set based on the tolerance of the engagement buckle in the axial direction and the tolerance of the interval between the inner side surfaces of the end portions of the pair of wall portions.

3. The electromagnetic flowmeter according to claim 1, characterized in that: The overlap amount between the lower surface of the covering member and the top surfaces of the ends of the pair of wall portions is set based on the tolerance of the covering member in the axial direction and the tolerance of the interval between the second contact surfaces of the pair of wall portions.

4. The electromagnetic flowmeter according to claim 1, characterized in that: The distance between the side surface of the covering member and the outer side surfaces of the end portions of the pair of wall portions is set based on the tolerance of the engagement buckle in the axial direction and the tolerance of the distance between the outer side surfaces of the end portions of the pair of wall portions.

5. The electromagnetic flowmeter according to any one of claims 1 to 4, characterized in that: The sensor component includes an exciting coil that generates a magnetic field in a direction perpendicular to a direction in which the fluid flows in the measuring tube, and an electrode that detects an electromotive force generated by the passage of the fluid.

Images