JP6622092B2 - Flowmeter - Google Patents

Description

  The present invention relates to a flow meter in which a measurement unit is mounted on a cylindrical body connected in the middle of piping.

  Conventionally, as this type of flow meter, the measurement unit is supported by the cylindrical body in a cantilever state inserted through a mounting hole that penetrates the cylindrical wall of the cylindrical body. One that measures the flow rate of a fluid at a rushed portion is known (for example, see Patent Document 1).

Japanese Utility Model Publication No. 63-163417 (page 4, line 18 to page 5, line 11, line 1)

  By the way, in order to make the measurement unit replaceable, it can be considered that the measurement unit is detachably attached to the cylindrical body. However, in the above-described conventional flowmeter, since the measurement unit is supported in a cantilever shape, the measurement unit is pushed to the outside of the cylindrical body by the fluid pressure in the cylindrical body, and the position of the measurement unit is shifted. There was a problem. Moreover, when the deviation | shift amount of the measurement unit is large, the problem that a measurement unit may remove | deviate from a cylindrical body may also arise.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a flow meter capable of suppressing the displacement of a measurement unit detachably attached to a cylindrical body.

In order to achieve the above object, the invention of claim 1 is characterized in that a cylindrical body connected in the middle of a pipe and having an in-cylinder flow path through which the fluid flowing through the pipe can pass, and the in-cylinder flow A flowmeter having a mounting hole extending radially outward from a path and opening at a side portion of the cylindrical body, and a measurement unit that is detachably attached to the mounting hole and measures the flow rate of the fluid. The measuring unit is inserted through the mounting hole and penetrates into the in-cylinder flow path, and passes through the portion of the shaft part that has entered the in-cylinder flow path along the axial direction of the tubular body. A shaft through hole and a measuring unit that measures the flow rate of the fluid flowing through the shaft through hole, and the mounting holes are provided in pairs so as to face each other in the radial direction of the cylindrical body, The shaft portion has the cylindrical body. Is pointing passed to the portion where the mounting hole is formed of a pair of I, is inserted into both of the pair of mounting holes Rutotomoni, form a reduced diameter structure at an intermediate portion in the axial direction, the A large diameter portion and a small diameter portion are provided on one side and the other side in the axial direction with respect to the reduced diameter portion, and the pair of mounting holes includes a large diameter hole through which the large diameter portion is inserted, and the large diameter portion. A small-diameter hole through which the small-diameter portion is inserted with a smaller diameter than the diameter hole, and the measurement unit is fitted into the large-diameter portion and seals between the large-diameter hole, and And a small-diameter seal member that is fitted to the small-diameter portion and seals between the small-diameter holes .

According to the second aspect of the invention, a portion of the inner peripheral surface of the small-diameter hole that faces the in-cylinder flow path is formed with a small-diameter expansion portion that increases in diameter toward the in-cylinder flow path side, and the portion facing the outside of the cylindrical body of the inner peripheral surface of the diameter hole, flow meter according to claim 1, the large-diameter extension portion is formed to be expanded toward the outside of the cylindrical body It is.

[Invention of Claim 1 ]
In the present invention, the shaft portion of the measurement unit is inserted into the mounting hole of the cylindrical body, and the measurement portion measures the flow rate of the fluid flowing through the shaft through hole formed in the shaft portion. Here, in the present invention, the mounting holes are provided in pairs so as to face each other in the radial direction of the cylindrical body, and the shaft portion is inserted into a portion of the cylindrical body where the pair of mounting holes are formed. It arrange | positions so that it may be passed and is penetrated by both of a pair of mounting holes. Therefore, the fluid pressure received by the shaft portion from the fluid flowing through the in-cylinder flow path can be canceled in the opposing direction of the pair of mounting holes, and the displacement of the measurement unit can be suppressed.

By the way, in the structure of the flowmeter of this invention, when attaching a measurement unit to a cylindrical body, a shaft part is penetrated from one outside into one attachment hole among a pair of attachment holes, and the front-end | tip of a shaft part is made into the other. Insert it into the mounting hole. At this time, if the pair of mounting holes have the same diameter, it may be difficult to insert the tip of the shaft portion into one of the mounting holes. Further, it is conceivable to seal between the shaft portion and the mounting hole by a sealing member fitted to the shaft portion. When the pair of mounting holes have the same diameter, the one mounting hole has a shaft portion. When the tip portion is inserted, there may be a problem that a seal member for sealing between the other mounting hole is damaged or dropped. On the other hand, in the invention of claim 1 , the shaft portion has a structure in which the diameter is reduced at the intermediate portion in the axial direction, and the large diameter portion is provided on one side and the other side in the axial direction with respect to the reduced diameter portion. Since the pair of mounting holes is composed of a large-diameter hole through which the large-diameter portion is inserted and a small-diameter hole through which the small-diameter portion is inserted with a smaller diameter than the large-diameter hole, If the shaft portion is inserted into a pair of mounting holes with the small diameter portion at the tip, the small diameter portion can be easily inserted into the large diameter hole, and the small diameter seal member fitted to the small diameter portion can be damaged or dropped off. It can be suppressed.

[Invention of claim 2 ]
In the present invention, a small diameter expansion portion that is expanded toward the in-cylinder flow path side is formed in a portion of the inner peripheral surface of the small diameter hole facing the in-cylinder flow path, so that the shaft inserted through the large diameter hole When the small-diameter portion of the portion is inserted through the small-diameter hole, the small-diameter expanded portion can guide the small-diameter portion into the small-diameter hole. Further, in the present invention, the large-diameter expansion portion that is expanded toward the outside of the cylindrical body is formed on the inner peripheral surface of the large-diameter hole on the outer surface of the cylindrical body. When the small diameter portion is inserted into the large diameter hole, the small diameter portion can be guided into the large diameter hole by the large diameter expansion portion.

Side sectional view of a flow meter according to an embodiment of the present invention. Enlarged view around the measurement unit in Fig. 1 Front section of flow meter Disassembled perspective view of flow meter (A) Side sectional view of shaft part, (B) Side sectional view of large diameter hole and small diameter hole Side cross-sectional view of the measurement unit and cylindrical body before the shaft is inserted into the large-diameter hole Side sectional view of the measurement unit and cylindrical body before the shaft is inserted into the small-diameter hole Side sectional view around the measurement unit of the flowmeter according to another embodiment

  Hereinafter, an embodiment in which the present invention is applied to an electromagnetic flow meter will be described with reference to FIGS. As shown in FIG. 1, in the flow meter 10 of the present embodiment, the axial intermediate portion of the cylindrical body 11 is covered with the case portion 60, and the measurement unit 30 is accommodated in the case portion 60. It has a structure.

  The cylindrical body 11 is connected in the middle of the pipe 90, and an in-cylinder channel 13 through which the fluid flowing through the pipe 90 can pass is formed inside the cylindrical wall 12 of the cylindrical body 11. In addition, a mounting hole 20 that extends radially outward from the in-cylinder flow path 13 and opens at the side of the cylindrical body 11 is formed at an axially intermediate portion of the cylindrical body 11. Specifically, the cylindrical body 11 is provided with a branch pipe 14 that protrudes radially outward from an axial intermediate portion of the cylindrical wall 12, and a mounting hole 20 is formed by an inner portion of the branch pipe 14. (See FIGS. 4 and 5B). Note that flanges 11 </ b> F connected to the flange 90 </ b> F of the pipe 90 are formed at both ends in the axial direction of the cylindrical body 11.

  The case portion 60 has a box shape and has body receiving holes 60 </ b> A and 60 </ b> A for receiving the cylindrical wall 12 of the cylindrical body 11. Specifically, as shown in FIGS. 1 and 4, the case portion 60 can be divided into an upper case body 61 whose bottom is open and a lower case body 62 whose top is open. A pair of opposed side walls 62S and 62S arranged opposite to each other in the axial direction of the cylindrical body 11 in the lower case body 62 are formed with notches 62K and 62K extending downward from the upper end of the lower case body 62. Yes. Further, the bottom opening of the upper case body 61 is slightly larger than the upper opening of the lower case body 62. And when both case bodies 61 and 62 are couple | bonded, 60 A of body receiving holes are formed because the side wall 61S of the upper case body 61 overlaps with the upper end part of the notch part 62K in the lower case body 62. As shown in FIG.

  As shown in FIGS. 2 and 4, the measurement unit 30 has a substantially T shape in side view in which the leg portion 30 </ b> B is suspended from the lower surface of the box portion 30 </ b> A. Specifically, the measurement unit 30 is formed by connecting a shaft portion 40 disposed below the intermediate position to a legged head portion 31 disposed above the intermediate position of the leg portion 30B.

  As shown in FIG. 2, the shaft portion 40 is inserted through the mounting hole 20 of the cylindrical body 11, and the legged head portion 31 is disposed outside the cylindrical body 11. Further, an annular groove 40M is formed on the outer peripheral portion of the shaft portion 40, and the shaft portion 40 and the mounting hole 20 are sealed by a seal member 45 fitted into the annular groove 40M.

  A part of the shaft portion 40 enters the in-cylinder flow path 13, and a shaft through hole 40 </ b> A that extends along the axial direction of the cylindrical body 11 is formed in the intrusion portion. Then, the fluid in the in-cylinder channel 13 flows through the shaft through hole 40A.

  As shown in FIG. 3, the shaft portion 40 incorporates a measuring portion 50 that measures the flow rate of the fluid flowing through the shaft through hole 40 </ b> A. Specifically, the measurement unit 50 includes a core 51 around which a coil 52 is wound, a pair of detection electrodes 53 and 53, and a voltmeter (not shown) that measures a voltage between the pair of detection electrodes 53 and 53. Z)). The core 51 is substantially U-shaped, and is disposed so as to sandwich the shaft through hole 40A at both ends, for example, in the horizontal direction. The pair of detection electrodes 53 and 53 are arranged so as to sandwich the shaft through-hole 40A in the vertical direction, for example. An opening 53A that exposes each detection electrode 53 is formed on the inner peripheral surface of the shaft through hole 40A, and the pair of detection electrodes 53 and 53 are in contact with the fluid flowing inside the shaft through hole 40A. It has become. When the fluid flows in the shaft through hole 40A with the coil 52 energized, a potential difference corresponding to the flow velocity of the fluid is generated between the pair of detection electrodes 53 and 53, and this potential difference is not shown in the figure. It has come to be measured by.

  Inside the legged head portion 31 (see FIG. 4), there is an arithmetic unit that calculates the flow rate of the fluid flowing through the shaft through hole 40A from the measurement result of the measuring unit 50 (that is, the flow velocity of the fluid flowing through the shaft through hole 40A). (Not shown). The legged head unit 31 is provided with, for example, a display unit that displays the calculation result of the calculation unit, a transmission unit that wirelessly transmits the calculation result to the outside, and the like.

  Here, in the flow meter 10 of the present embodiment, the mounting holes 20 are provided in pairs so as to face each other in the radial direction of the cylindrical body 11. The shaft portion 40 of the measuring unit 30 is arranged so as to be passed to a portion of the cylindrical body 11 in which the pair of mounting holes 20 and 20 are formed, that is, the pair of branch pipes 14 and 14. A pair of mounting holes 20 and 20 are inserted. The annular groove 40M is provided at two locations near the distal end portion and the proximal end portion of the shaft portion 40, and the seal member 45 fitted into each annular groove 40M is connected to the shaft portion 40 and the mounting hole 20. It is sealed between. Further, in a state where the shaft portion 40 is attached to the pair of mounting holes 20, 20, the shaft through hole 40 </ b> A is disposed substantially coaxially with the central axis of the cylindrical body 11.

  Thus, in this embodiment, the cylindrical body 11 is provided with a pair of mounting holes 20 so as to face each other in the radial direction, and the shaft portion 40 of the measuring unit 30 is one of the cylindrical bodies 11. Since it arrange | positions so that it may pass across the part (namely, a pair of branch pipes 14 and 14) in which the pair of mounting holes 20 and 20 were formed, the shaft part 40 receives from the fluid which flows through the in-cylinder flow path 13. It becomes possible to cancel the fluid pressure in the opposing direction of the pair of mounting holes 20, 20, and to suppress the displacement of the measurement unit 30.

  As shown in FIG. 4, the flow meter 10 is formed by assembling the measurement unit 30 and the case portion 60 (that is, the upper case body 61 and the lower case body 62) to the cylindrical body 11. . Specifically, first, the shaft portion 40 of the measurement unit 30 is inserted into the one mounting hole 20 of the pair of mounting holes 20, 20 from the outside of the cylindrical body 11 (see FIG. 6). If the shaft part 40 penetrates one mounting hole 20, the shaft part 40 is further inserted and the front-end | tip part of the shaft part 40 is inserted in the other mounting hole 20 (refer FIG. 7). When the shaft portion 40 is inserted into both the pair of mounting holes 20, 20, the intermediate portion of the cylindrical body 11 is then vertically sandwiched between the upper case body 61 and the lower case body 62, and these upper case bodies 61 and the lower case body 62 are coupled together to accommodate the measurement unit 30 in the case portion 60. Thus, the flow meter 10 shown in FIG. 1 is completed.

  Here, when the pair of mounting holes 20 and 20 have the same size (in this case, both end portions of the shaft portion 40 have the same size), the shaft portion 40 is inserted into the mounting hole 20. It can be difficult. Further, when the shaft portion 40 is inserted into one mounting hole 20, the seal member 45 for sealing between the other mounting hole 20 is damaged by collision with the branch pipe 14 or friction, or the annular groove 40 </ b> M. Or the sealing performance between the shaft portion 40 and the mounting hole 20 may be deteriorated. In order to prevent such a situation, the flow meter 10 of the present embodiment has a configuration described below.

  That is, as shown in FIG. 5A, the shaft portion 40 has a structure in which the diameter is reduced in the axially intermediate portion and the side far from the legged head portion 31 and the diameter is increased from the legged head portion 31 side. The part 41, the reduced diameter part 42, and the small diameter part 43 are arranged in the axial direction. The annular groove 40M is formed in the large-diameter portion 41 and the small-diameter portion 43, and the pair of seal members 45, 45 includes a large-diameter seal member 45A fitted in the annular groove 40M of the large-diameter portion 41 and a small-diameter portion. And a small-diameter seal member 45B fitted in the 43 annular grooves 40M. Further, the reduced diameter portion 42 is formed in a tapered shape that is gradually reduced in diameter toward the small diameter portion 43 side. Specifically, the reduced diameter portion 42 is disposed on the large diameter portion 41 side with respect to the shaft through hole 40A, and more than half of the shaft portion 40 is configured by the small diameter portion 43.

  As shown in FIG. 5 (B), the pair of mounting holes 20 and 20 are composed of a large diameter hole 21 and a small diameter hole 22 having different diameters. In the state where the measurement unit 30 is assembled to the cylindrical body 11, the large diameter portion 41 of the shaft portion 40 is inserted into the large diameter hole 21, and the small diameter portion 43 of the shaft portion 40 is inserted into the small diameter hole 22. It has become. Specifically, the inner diameter of the large-diameter hole 21 is slightly larger than the outer diameter of the large-diameter portion 41, and the large-diameter hole 21 and the large-diameter portion 41 are sealed by a large-diameter seal member 45A. Is done. Further, the inner diameter of the small diameter hole 22 is slightly larger than the outer diameter of the small diameter portion 43, and the small diameter hole 22 and the small diameter portion 43 are sealed by the small diameter seal member 45B.

  On the inner peripheral surface of the large-diameter hole 21, an outer expansion portion 21 </ b> A whose diameter increases toward the outer side of the cylindrical body 11 is formed on a portion facing the outer side of the cylindrical body 11 (the side far from the in-cylinder flow path 13). Is formed. In addition, an inner expansion portion 21 </ b> B whose diameter is increased toward the in-cylinder flow path 13 side is formed in a portion of the inner peripheral surface of the large-diameter hole 21 that faces the in-cylinder flow path 13. In the example of the present embodiment, both the outer extension portion 21A and the inner extension portion 21B are formed in an R shape. The inner diameter of the large-diameter hole 21 described above means the minimum diameter of the large-diameter hole 21.

  On the inner peripheral surface of the small-diameter hole 22, an inner extension portion 22 </ b> B whose diameter is increased toward the in-cylinder channel 13 is formed in a portion facing the in-cylinder channel 13. In the example of the present embodiment, the inner extension 22B is formed in the same R shape as the inner extension 21B described above. Moreover, the part which faces the outer side of the cylindrical body 11 among the small diameter holes 22 is straight. The inner diameter of the small diameter hole 22 described above means the minimum diameter of the small diameter hole 22.

  Thus, in the flowmeter 10 of the present embodiment, the shaft portion 40 has the large diameter portion 41 and the small diameter portion 43, and the pair of mounting holes 20, 20 has a large diameter through which the large diameter portion 41 is inserted. Since the hole 21 and the small-diameter hole 22 having a smaller diameter than the large-diameter hole 21 and the small-diameter portion 43 are inserted, as shown in FIG. When the small diameter portion 43 is inserted into the large diameter hole 21, the large diameter hole 21 can be easily inserted into the pair of mounting holes 20, 20 of the shaft portion 40. Collision and friction between the branch pipes 14 and the small-diameter seal member 45B are suppressed, and damage and dropout of the small-diameter seal member 45B are suppressed.

  Further, in the present embodiment, the inner expansion portion 22B whose diameter is increased toward the in-cylinder flow path 13 side is formed in the portion facing the in-cylinder flow path 13 in the inner peripheral surface of the small diameter hole 22, When the small diameter portion 43 of the shaft portion 40 penetrating the large diameter hole 21 is inserted into the small diameter hole 22, the small diameter portion 43 can be guided into the small diameter hole 22 by the inner expansion portion 22B. Further, in the present embodiment, an outer expansion portion 21 </ b> A that is expanded in diameter toward the outside of the cylindrical body 11 is formed in a portion of the inner peripheral surface of the large-diameter hole 41 that faces the outside of the cylindrical body 11. Therefore, when the small-diameter portion 43 of the shaft portion 40 is inserted into the large-diameter hole 21, it is possible to guide the small-diameter portion 43 into the large-diameter hole 21 by the outer expansion portion 21A, and the large-diameter of the shaft portion 40. Even when the portion 41 is inserted through the large-diameter hole 21, the large-diameter portion 41 can be guided into the large-diameter hole 21 by the outer expansion portion 21A. In the present embodiment, the outer expanded portion 21A of the large diameter hole 21 corresponds to the “large diameter expanded portion” of the present invention, and the inner expanded portion 22B of the small diameter hole 22 corresponds to the “small diameter expanded portion” of the present invention. .

  This completes the description of the configuration of the flow meter 10 of the present embodiment. Next, the effect of the flow meter 10 will be described.

  In the flow meter 10 of the present embodiment, the cylindrical body 11 is provided with a pair of mounting holes 20, 20 that are opposed in the radial direction, and the shaft portion 40 of the measurement unit 30 has a pair of mounting holes 20, 20. Therefore, the fluid pressure received by the shaft portion 40 from the fluid flowing through the in-cylinder flow path 13 can be canceled in the opposing direction of the pair of mounting holes 20, 20, and the displacement of the measurement unit 30 can be suppressed. It becomes possible.

  Further, the shaft portion 40 is formed with a large diameter portion 41 and a small diameter portion 43, and the pair of mounting holes 20, 20 are constituted by a large diameter hole 21 and a small diameter hole 22. When the unit 30 is assembled, the shaft portion 40 is inserted into the pair of mounting holes 20 and 20 with the small-diameter portion 43 at the tip, so that the shaft portion 40 can be inserted into the pair of mounting holes 20 and 20. It becomes easy. Further, collision and friction between the branch pipe 14 constituting the large diameter hole 21 and the small diameter seal member 45B are suppressed, and damage and dropout of the small diameter seal member 45B are suppressed.

  In addition, an inner expansion portion 22B that is expanded in diameter toward the in-cylinder flow path 13 side is formed in a portion of the inner peripheral surface of the small-diameter hole 22 that faces the in-cylinder flow path 13. When the small diameter portion 43 is inserted into the small diameter hole 22, the small diameter portion 43 can be guided into the small diameter hole 22 by the inner expansion portion 22 </ b> B. Further, in the present embodiment, an outer expansion portion 21 </ b> A whose diameter increases toward the outer side of the cylindrical body 11 is formed in a portion facing the outer side of the cylindrical body 11 on the inner peripheral surface of the large-diameter hole 21. Therefore, when the large-diameter portion 41 and the small-diameter portion 43 of the shaft portion 40 are inserted into the large-diameter hole 21, the large-diameter portion 41 and the small-diameter portion 43 can be guided into the large-diameter hole 21 by the outer expansion portion 21A. It becomes.

[Other Embodiments ]

  (1) In the above embodiment, the present invention is applied to an electromagnetic flow meter. However, for example, the present invention may be applied to a flow meter other than an electromagnetic flow meter such as an ultrasonic flow meter or a thermal flow meter. .

  (2) In the above embodiment, both the outer extended portion 21A of the large diameter hole 21 and the inner extended portion 22B of the small diameter hole 22 are R-shaped, but one or both may be tapered. That is, the outer extended portion 21A may have a tapered shape whose diameter is increased toward the outside of the cylindrical body 11, or the inner extended portion 22B is tapered whose diameter is increased toward the in-cylinder flow path 13 side. It may be a shape.

  (3) In the above embodiment, the reduced diameter portion 42 of the shaft portion 40 is formed in a tapered shape, but may be formed in a stepped shape. In addition, according to the configuration of the above embodiment, the reduced diameter portion 42 can be easily inserted into the large diameter hole 21.

  (4) In the above embodiment, the outer peripheral portion 21 </ b> A may not be provided on the inner peripheral surface of the large-diameter hole 21. Even in this case, the small-diameter portion 43 of the shaft portion 40 can be guided to the small-diameter hole 22 by the inner extended portion 22B of the small-diameter hole 22.

  (5) In the above embodiment, the pair of mounting holes 20, 20 may have the same diameter. At that time, if the configuration is such that an expanded portion that is expanded in diameter toward the in-cylinder flow path 13 side is formed in a portion facing the in-cylinder flow path 13 on the inner peripheral surface of the one mounting hole 20. Similarly to the inner expansion portion 22B of the embodiment, the tip portion of the shaft portion 40 can be guided to the one mounting hole 20 to facilitate the insertion of the shaft portion 40 into the one mounting hole 20. .

  (6) In the above embodiment, the mounting holes 20 and 20 are formed by the branch pipes 14 and 14 protruding from the cylindrical wall 12, but for example, as shown in FIG. The mounting holes 20 and 20 may be formed by through holes 12A and 12A penetrating the cylindrical wall 12. In this case, the cylindrical wall 12 may be thick over the entire axial direction, or only the portion where the measurement unit 30 is assembled may be thick. In the example of FIG. 8, the inner diameter of each through-hole 12A is constant over the entire axial direction, but the end of the one through-hole 12A that faces the outside of the cylindrical body 11 is the cylindrical body. 11, the end of the other through-hole 12A on the in-cylinder channel 13 side may be expanded as it approaches the in-cylinder channel 13 side.

  (7) In the above-described embodiment, the both end portions of the shaft portion 40 may be screwed into the pair of mounting holes 20 and 20. Specifically, screw portions may be formed on the outer peripheral surfaces of both end portions of the shaft portion 40, and the pair of mounting holes 20, 20 may be screw holes. According to this configuration, it is possible to prevent the screw from being loosened by the fluid pressure received by the shaft portion 40, and to suppress the displacement of the shaft portion 40.

DESCRIPTION OF SYMBOLS 10 Flowmeter 11 Cylindrical body 13 In-cylinder flow path 20 Mounting hole 21 Large diameter hole 21A Outer expansion part (large diameter expansion part)
22 Small diameter hole 22B Inside expansion part (small diameter expansion part)
30 Measuring Unit 40 Shaft Part 41 Large Diameter Part 43 Small Diameter Part 45A Large Diameter Seal Member 45B Small Diameter Seal Member 50 Measuring Part 90 Piping

Claims (2)

A cylindrical body that is connected in the middle of the pipe and has an in-cylinder flow path on the inside through which the fluid flowing through the pipe can pass;
A mounting hole extending radially outward from the in-cylinder channel and opening at a side of the cylindrical body;
In a flow meter having a measurement unit that is detachably attached to the mounting hole and measures the flow rate of the fluid,
The measurement unit is inserted through the mounting hole and penetrates into the in-cylinder flow path, and penetrates the portion of the shaft part that has entered the in-cylinder flow path along the axial direction of the cylindrical body. A shaft through-hole, and a measuring unit that measures the flow rate of the fluid flowing through the shaft through-hole,
The mounting holes are provided in pairs so as to face each other in the radial direction of the cylindrical body,
The shaft portion is pointed passed to the portion where the mounting hole is formed of a pair of said cylindrical body, is inserted into both of the pair of mounting holes Rutotomoni, reduced diameter at an intermediate portion in the axial direction And having a large diameter portion and a small diameter portion on one side and the other side in the axial direction with respect to the reduced diameter portion,
The pair of mounting holes includes a large-diameter hole through which the large-diameter portion is inserted, and a small-diameter hole through which the small-diameter portion is inserted with a smaller diameter than the large-diameter hole,
The measurement unit includes a large-diameter seal member that is fitted to the large-diameter portion and seals between the large-diameter holes, and a small-diameter seal member that is fitted to the small-diameter portions and seals between the small-diameter holes. And a flow meter having . A portion of the inner peripheral surface of the small-diameter hole that faces the in-cylinder flow path is formed with a small-diameter expansion portion that increases in diameter toward the in-cylinder flow path side,
2. The large-diameter expansion portion that is enlarged in diameter toward the outside of the cylindrical body is formed in a portion of the inner peripheral surface of the large-diameter hole that faces the outside of the cylindrical body. Flowmeter.

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