JP2020003465A - Structure for preventing wrong assembly of component for measuring flow rate of gas meter - Google Patents

Abstract

To provide a structure for preventing wrong assembly of a component for measuring a flow rate of a gas meter, which can prevent wrong assembly of a measuring unit and a straightening plate simply and reliably.SOLUTION: In a portion of an internal gas flow passage formed at the bottom of a meter case 2 closed by a bottom cover 3, an inlet straightening plate 16, an ultrasonic measuring unit 15, and an outlet straightening plate 17 are mounted. Inside the bottom of the meter case 2, guide grooves 30, 25, and 26 for guiding the mounting of the measuring unit 15, the inlet straightening plate 16, and the outlet straightening plate 17 are formed, respectively. In the measuring unit 15, the inlet straightening plate 16, and the outlet straightening plate 17, protrusions 16f, 17f guided along the guide grooves 30, 25, 26 are formed, respectively. The combination of these guide grooves and projections prevents these components from being wrongly assembled in a state of being reversed.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a gas meter having a built-in ultrasonic measuring unit for measuring a gas flow rate. More specifically, the present invention relates to a measurement unit and an erroneous assembly prevention structure for preventing erroneous assembly of an inlet rectifying plate and an outlet rectifying plate disposed on the inlet side and the outlet side thereof.

  As described in Patent Documents 1 and 2, there is known an ultrasonic gas meter that measures a gas flow rate using a measurement unit provided with an ultrasonic flow velocity sensor. In such an ultrasonic gas meter, a gas inlet and a gas outlet are provided on the top surface of the meter case, and a U-shaped internal gas for guiding gas from the gas inlet to the gas outlet is provided inside the meter case. A flow path is formed, and an ultrasonic measurement unit that measures the gas flow rate based on the propagation time of the ultrasonic wave is mounted at the bottom of the gas meter in the internal gas flow path.

  In addition, in order to increase the measurement accuracy, an inlet straightening plate is arranged on the upstream side of the measuring unit, and an outlet straightening plate is arranged on the downstream side thereof. Rectifying the flow. The measurement unit, the inlet straightening plate, and the outlet straightening plate (hereinafter, these are referred to as flow rate measuring components) are attached to the internal gas flow path from the bottom opening of the meter case. With these components mounted, the bottom opening is closed by the bottom cover.

  The directions of assembling the measuring unit and the rectifying plate are predetermined, and their front ends (gas inflow side) face the upstream side of the gas flow path, and their rear ends (gas outflow side) downstream of the gas flow path. Assembled with facing. If these components are incorrectly assembled, the gas flow rate cannot be measured accurately, so it is necessary to reliably prevent erroneous assembly.

JP 2012-103087 A JP-A-2017-129391

  Here, the measurement unit and the rectifying plate often have symmetrical contours in the front-rear direction. In accordance with this, the measurement unit formed in the internal gas flow path on the meter case side and the mounting portion of the rectifying plate also have an inner peripheral surface shape that is symmetrical in the front-rear direction. In some cases, the measurement unit and the rectifier plate can be assembled to the internal gas flow path even in the reverse direction. For this reason, in assembling these parts, it is necessary to pay attention to the marks before and after attached to the measuring unit so as not to erroneously assemble them. Similarly, it is necessary to perform an assembling operation with care so that the current plate is not turned upside down. Furthermore, when rectifying plates are arranged on the front end side and the rear end side of the measurement unit, it is necessary to pay attention to erroneous assembly in which the front and rear rectifying plates are arranged in reverse.

  SUMMARY OF THE INVENTION In view of the foregoing, an object of the present invention is to provide a structure for preventing erroneous assembly of a flow rate measuring component of a gas meter, which can easily and reliably prevent erroneous assembly of a measurement unit and a rectifier plate.

  In order to solve the above-mentioned problem, the present invention provides an inlet gas flow path in an internal gas flow path of the meter case, a measurement unit mounting portion, and an outlet gas flow path from the bottom opening of the meter case. In a gas meter in which a rectifying plate, an ultrasonic measuring unit and an outlet rectifying plate are mounted, and the bottom opening is closed by a bottom cover attached to the bottom of the meter case, a flow measuring component of the gas meter is used. The misassembly prevention structure is configured as follows.

  The inlet gas flow path is formed with an inlet gas flow path side guide that guides the mounting of the inlet flow straightening plate. An inlet rectifying plate side guide portion for guiding the mounting of the plate into the inlet gas flow path is formed. The inlet straightening plate side guide portion can be positioned at a position where it is engaged with the inlet gas flow passage side guide portion only when the inlet straightening plate is mounted on the inlet gas flow passage with the front and rear directions correct. Similarly, the outlet gas flow path is formed with an outlet gas flow path side guide portion for guiding the mounting of the outlet flow straightening plate, and the outlet flow straightening plate is engaged with the outlet gas flow path side guide portion. An outlet current plate side guide portion for guiding the installation of the outlet current plate in the outlet gas flow path is formed. The exit straightening plate side guide portion can be positioned at a position where it is engaged with the outlet gas flow passage side guide portion only when the outlet straightening plate is mounted on the outlet gas flow passage with the front and rear directions correct.

  When the inlet straightening plate is installed in the inlet gas flow path with the front and rear directions correct, the inlet straightening plate side guide section is guided by the inlet gas flow path side guide section and can be installed in the inlet gas flow path. is there. On the other hand, when the inlet rectifying plate is mounted on the inlet gas flow path in the reverse direction, the inlet rectifying plate side guide cannot be positioned at a position where it can be engaged with the inlet gas flow path side guide. Therefore, the inlet straightening plate cannot be mounted. In addition, even when the inlet straightening plate is attached to the outlet gas flow path, the inlet straightening plate side guide cannot be positioned at a position where it can be engaged with the outlet gas flow side guide portion. Cannot be installed.

  Similarly, when the outlet straightening plate is attached to the outlet gas flow path in a state where the front and rear directions are correct, the outlet straightening plate side guide is guided by the outlet gas flow path side guide and is connected to the outlet gas flow path. Can be mounted. On the other hand, when the outlet straightening plate is mounted in the outlet gas flow path in the reverse direction, the outlet straightening plate side guide cannot be positioned at a position where it can be engaged with the outlet gas flow side guide. Therefore, the outlet straightening plate cannot be mounted. Further, even when the outlet straightening plate is attached to the inlet gas flow path, the outlet straightening plate side guide cannot be positioned at a position where the outlet straightening plate can be engaged with the inlet gas flow side guide portion. Cannot be installed.

  As described above, according to the present invention, it is possible to reliably prevent an erroneous assembly in which each of the inlet straightening plate and the outlet straightening plate is mounted with the front and rear directions reversed. In addition, it is possible to reliably prevent an erroneous assembly in which these are mounted in reverse positions.

  Next, in the erroneous assembly prevention structure of the present invention, the measurement unit mounting portion is formed with a measurement unit mounting portion side guide portion for guiding the mounting of the measurement unit. In addition, when the measurement unit is mounted in a state where the front and rear directions are correct, the measurement unit is guided to a predetermined regular mounting position along the measurement unit mounting portion side guide portion, and the front and rear directions are set. When the is mounted in the reverse state, a measurement unit side guide portion is formed along the measurement unit mounting portion side guide portion to guide the erroneous mounting position deviating from the regular mounting position.

  If the measuring unit is mounted on the unit mounting part with the front and rear directions reversed, the measuring unit side guiding part will be guided by the measuring unit mounting part side guiding part, and the measuring unit will be displaced from the proper mounting position. It is attached to the attachment position. By checking the mounting position of the measurement unit, the operator can know that the direction of the measurement unit is reversed. Thereby, erroneous assembly can be prevented.

  Next, in the erroneous assembly prevention structure of the present invention, the measurement unit is formed with a measurement unit side bottom cover guide portion for guiding attachment of the bottom cover to the meter case, and the measurement unit side bottom cover is formed on the bottom cover. A bottom cover side guide portion is formed to engage with the cover guide portion and guide the attachment of the bottom cover to the bottom. The bottom cover-side guide can be positioned at a position where the bottom cover-side guide engages with the measurement unit-side bottom cover guide only when the measurement unit is mounted at the regular mounting position.

  When the measurement unit is mounted upside down, even if you try to attach the bottom cover to the bottom of the meter case, attach the bottom cover bottom guide of the bottom cover to the measurement unit side bottom cover guide that is incorrectly assembled. Positioning is not possible and the bottom cover cannot be attached. Thereby, the worker can know the erroneous assembly of the measuring unit. Therefore, it is possible to easily and reliably know that the measurement unit has been erroneously assembled, so that erroneous assembly can be reliably prevented.

It is the top view, front view, and bottom view which show an example of the gas meter which applied this invention. FIG. 2 is a schematic longitudinal sectional view of the gas meter of FIG. 1 and a bottom view of the gas meter with a bottom cover removed. FIG. 2 is a schematic exploded perspective view showing a bottom portion of the gas meter of FIG. 1. FIG. 2 is a perspective view showing an inlet straightening plate of the gas meter of FIG. 1. FIG. 2 is a perspective view showing an outlet straightening plate of the gas meter of FIG. 1. FIG. 2 is a plan view, a front view, an outlet side end view, a bottom view, and a bottom view when the front and rear are reversed, showing the measurement unit of the gas meter of FIG. 1. FIG. 2 is a perspective view when a bottom cover of the gas meter of FIG. 1 is viewed from above.

  Hereinafter, an embodiment of a structure for preventing erroneous assembly of a flow rate measuring component of a gas meter to which the present invention is applied will be described with reference to the drawings.

[overall structure]
FIGS. 1A, 1B and 1C are a plan view, a front view and a bottom view, respectively, showing a gas meter according to an embodiment. 2A and 2B are a schematic vertical sectional view of the gas meter and a bottom view of the gas meter with the bottom cover removed.

  The gas meter 1 includes a meter case 2 having a substantially rectangular outline as a whole, and a bottom cover 3 attached to the bottom of the meter case 2. The bottom opening 3 of the meter case 2 is closed by the bottom cover 3. On the upper surface of the meter case 2, a gas inlet 5 is open upward at one end in the width direction, and a gas outlet 6 is open upward at the other end. A control unit 8 having a liquid crystal display 7 is mounted on a central portion of the meter case 2 in the width direction.

  Inside the case of the meter case 2, a U-shaped internal gas flow path for guiding the gas to be measured from the gas inlet 5 to the gas outlet 6 is formed. The internal gas passage includes an upstream gas passage 11 extending from the gas inlet 5 toward the bottom of the meter case 2, and an intermediate gas extending laterally from the downstream end between the meter case 2 and the bottom cover 3. It comprises a flow path 12 and a downstream gas flow path 13 extending upward from the downstream end to the gas outlet 6. A communication port 11 a that can be opened and closed by a gas cutoff valve 14 is formed in the middle of the upstream gas passage 11.

  A measurement unit mounting portion 12b is formed in a part of the intermediate gas flow path 12 extending along the bottom of the meter case 2. A measuring unit 15 having an ultrasonic flow sensor is mounted on the measuring unit mounting portion 12b. A channel portion in the middle of the intermediate gas channel 12 is defined by a unit internal gas channel 15 b formed inside the measurement unit 15. In the intermediate gas flow path 12, an inlet gas flow path 12a is formed between the upstream gas flow path 11 and the gas inlet 15a of the measurement unit 15, and an inlet rectifying plate 16 is mounted here. In the intermediate gas channel 12, an outlet gas channel 12c is formed between the gas outlet 15c of the measuring unit 15 and the downstream gas channel 13, and an outlet rectifying plate 17 is mounted here. ing.

  The gas flow flowing from the upstream gas passage 11 through the inlet gas passage 12a of the intermediate gas passage 12 into the gas inlet 15a of the measuring unit 15 is rectified by the inlet rectifying plate 16 while being rectified by the unit in the measuring unit 15. It flows into the internal gas passage 15b. The gas flow flowing out of the gas outlet 15c through the position measured by the measuring unit 15 flows into the downstream gas flow path 13 while being rectified by the outlet rectifying plate 17 arranged here. Since the gas flow passes through the measurement position of the unit internal gas flow path 15b of the measurement unit 15 in a rectified state by the front and rear inlet flow straightening plates 16 and the outlet current straightening plate 17, the gas flow rate can be accurately detected. Can do well.

  FIG. 3 is a schematic exploded perspective view showing a bottom portion of the gas meter 1. At the bottom of the meter case 2 of the gas meter 1, a horizontally long rectangular bottom opening 4 is formed as a whole. The bottom cover 3 is fastened and fixed to the opening edge 4a of the bottom opening 4 with a plurality of fastening screws 22 with a sealing member 21 interposed therebetween. The bottom opening 4 is closed by the bottom cover 3.

  When the bottom cover 3 is removed from the bottom of the meter case 2, the bottom opening 4 is exposed. A portion of the internal gas passage where the intermediate gas passage 12 is formed is exposed from the bottom opening 4 (see FIG. 2B). The measurement unit 15, the inlet straightening plate 16 and the outlet straightening plate 17 are attached to the portion where the intermediate gas flow path 12 is formed via the bottom opening 4. After mounting these parts, the bottom cover 3 is mounted. The measuring unit 15 is mounted in a state where the front and rear directions are set such that the gas inlet 15a faces the inlet gas flow channel 12a and the gas outlet 15c faces the outlet gas flow channel 12c. Similarly, the inlet straightening plate 16 and the outlet straightening plate 17 are also mounted in a state where the front and rear directions are set.

[Incorrect assembly prevention structure]
In the gas meter 1, the portion where the intermediate gas flow path 12 is formed and the measurement unit 15, the inlet straightening plate 16, and the outlet straightening plate 17 are erroneously oriented in the opposite directions. An erroneous assembly prevention structure is provided for preventing assembly from occurring and preventing the inlet rectifying plate 16 and the outlet rectifying plate 17 from being mounted in opposite positions. Hereinafter, the erroneous assembly prevention structure of this example will be described.

  Inside the bottom of the meter case 2, a portion of an intermediate gas flow path 12 including an inlet gas flow path 12a, a measurement unit mounting portion 12b, and an outlet gas flow path 12c is formed. These portions open from the bottom opening 4 to the outside of the case. The intermediate gas flow path 12 includes a front wall inner peripheral surface 2a, a rear wall inner peripheral surface 2b extending from the opening edge 4a of the bottom opening 4 of the meter case 2 toward the upper surface of the meter case 2, and a left and right side wall. It is formed between the peripheral surfaces 2c and 2d.

  The measurement unit mounting portion 12b includes left and right partition walls 23 and 24 that are bridged symmetrically between the front wall inner peripheral surface 2a and the rear wall inner peripheral surface 2b. The end surfaces of the partition walls 23 and 24 are cut out in a rectangular groove shape, and the measurement unit 15 is mounted on these portions from a direction orthogonal to the bottom opening 4. An inlet gas flow path 12a is formed between the partition wall 23 and the side wall inner peripheral surface 2c. The inlet gas flow path 12a is provided along the side wall of the partition wall 23 on the side of the side wall inner peripheral surface 2c. The inlet flow straightening plate 16 is mounted from a direction orthogonal to. Similarly, an outlet gas passage 12c is provided between the other partition plate 24 and the other inner peripheral surface 2d of the side wall. Here, the outlet gas flow path 12c is provided on the side surface of the partition wall 24 on the side of the inner peripheral surface 2d of the side wall. The outlet straightening plate 17 is mounted along a direction perpendicular to the bottom opening 4.

(Structure to prevent erroneous assembly of inlet rectifier plate)
First, with reference to FIGS. 3 and 4, a description will be given of a structure for preventing an erroneous assembly of the inlet rectifying plate 16. FIG. 4 is a perspective view when the inlet flow straightening plate 16 is viewed from above. The inlet gas flow path 12a is formed with a pair of guide grooves 25 (inlet gas flow path side guide portions) for guiding the mounting of the inlet flow straightening plate 16. The inlet flow straightening plate 16 is formed with a pair of guide projections 16f (an inlet straightening plate side guide portion). The projection 16f is positioned at a position where it can be engaged with the guide groove 25 when the projection 16f is mounted in a correct front and rear direction, and the mounting to the inlet gas flow path 12a is guided along the guide groove 25. In the case of mounting in the opposite direction, it cannot be positioned in the guide groove 25 and the inlet rectifying plate 16 cannot be mounted.

  The inlet straightening plate 16 is a U-shaped plate having a top plate portion 16a having a rectangular contour and left and right side plate portions 16b and 16c extending at right angles from both ends in the long side direction. In the inlet flow regulating plate 16, one end of the top plate portion 16a in the short side direction is a front end surface 16d, and the other end is a rear end surface 16e. The rear end face 16e has a rectangular concave groove shape to which a portion on the gas inlet 15a side of the measurement unit 15 can be attached.

  On the outer surfaces of the side plate portions 16b and 16c on both sides of the inlet flow straightening plate 16, elongated U-shaped frame-shaped protrusions 16f extending in a direction orthogonal to the top plate portion 16a are formed at symmetrical positions. . In this example, the projection 16f is located at the center in the width direction of the side plate portions 16b and 16c. On the other hand, in the inlet gas flow path 12a in which the inlet flow straightening plate 16 is mounted, the bottom opening 4 is located at the front wall inner peripheral surface 2a and the rear wall inner peripheral surface 2b at positions symmetrical in the longitudinal direction. A guide groove 25 having a rectangular cross section is formed at the opening edge 4a of the opening. The guide groove 25 is a groove having a length corresponding to the protrusion 16f, in which the protrusion 16f can be inserted from a direction orthogonal to the bottom opening 4.

  The guide grooves 25 and the projections 16f are arranged as follows so as to prevent erroneous assembly of the inlet flow straightening plate 16. When the inlet flow straightening plate 16 is mounted in the correct front-back direction, that is, when the rear end face 16e is mounted along the partition wall 23, the protrusion 16f can be inserted into the guide groove 25 (engagement). The projection 16f is guided along the guide groove 25, and the inlet straightening plate 16 is mounted to the position of the set depth. On the other hand, when the inlet flow straightening plate 16 is mounted with the front and rear sides reversed, even if the front end face 16 d is pushed along the partition wall 23, the position of the projection 16 f and the position of the guide groove 25 are shifted. Occurs, and the inlet straightening plate 16 cannot be mounted. Therefore, it is possible to prevent erroneous assembly in which the inlet flow straightening plate 16 is attached to the inlet gas flow channel 12a with the front and rear directions being wrong.

  When the inlet rectifying plate 16 is mounted upside down, the top plate portion 16a faces downward, and the portion of the measuring unit 15 on the gas inlet 15a side is replaced with the concave rear end face 16e. Cannot be attached to Therefore, erroneous assembly in which the inlet flow straightening plate 16 is attached to the inlet gas flow channel 12a in a state where the vertical direction is wrong can be prevented.

(Structure to prevent erroneous assembly of exit rectifier plate)
Next, with reference to FIGS. 3 and 5, a structure for preventing the outlet flow straightening plate 17 from being erroneously assembled will be described. FIG. 5 is a perspective view when the outlet straightening plate 17 is viewed from above. A pair of guide grooves 26 (outlet gas flow path side guide portions) are formed in the outlet gas flow path 12c to guide the mounting of the outlet flow straightening plate 17. The outlet straightening plate 17 is formed with a pair of projections 17f (outlet straightening plate side guide portions) that can be engaged with the guide grooves 26. When the outlet straightening plate 17 is mounted in a state where the front and rear directions are correct, the projection 17f engages with the guide groove 26 to guide the mounting to the outlet gas flow channel 12c. When mounted in the opposite direction, the protrusion 17f cannot be positioned at a position corresponding to the guide groove 26, and the outlet flow straightening plate 17 cannot be mounted.

  The outlet straightening plate 17 is a U-shaped plate having a top plate portion 17a having a rectangular contour and left and right side plate portions 17b and 17c extending at right angles from both ends in the long side direction. In the outlet straightening plate 17, one end of the top plate portion 17a in the short side direction is a front end surface 17d, and the other end is a rear end surface 17e. The front end face 17d has a rectangular concave groove shape to which a portion on the gas outlet 15c side of the measurement unit 15 can be attached.

  On the outer side surfaces of the side plate portions 17b and 17c on both sides of the outlet flow straightening plate 17, the ends on the side of the rear end surface 17e are respectively provided with symmetrical elongated U-shapes extending symmetrically in the direction orthogonal to the top plate portion 17a. A frame-like projection 17f is formed. On the other hand, the outlet gas flow channel 12c to which the outlet flow straightening plate 17 is attached has the bottom opening 4 at the front wall inner peripheral surface 2a and the rear wall inner peripheral surface 2b at symmetrical positions. A guide groove 26 having a rectangular cross section, one end of which is open, is formed at the opening edge of the opening. The guide groove 26 is a groove having a length corresponding to the protrusion 17f, in which the protrusion 17f can be inserted from a direction orthogonal to the bottom opening 4.

  The guide grooves 26 and the projections 17f are arranged as follows so as to prevent the outlet straightening plate 17 from being erroneously assembled. When the outlet straightening plate 17 is mounted in a state where the front and rear directions are correct, that is, when the front end face 17d is mounted along the partition wall 24, the projection 17f is provided at a position where it is engaged with the guide groove 26. The protrusion 17f is guided along the guide groove 26, and the outlet straightening plate 17 is mounted to the position of the set depth. On the other hand, when the outlet rectifying plate 17 is mounted with the front and rear reversed, the position of the projection 17f and the position of the guide groove 26 match even when the rear end face 17e is pushed along the partition wall 24. Therefore, the projection 17f interferes with the opening edge 4a, and the outlet straightening plate 17 cannot be mounted. Therefore, it is possible to prevent an erroneous assembly in which the outlet straightening plate 17 is attached to the outlet gas flow channel 12c with the front and rear directions being wrong.

  When the outlet straightening plate 17 is mounted upside down, the top plate portion 17a faces downward, and the portion of the measuring unit 15 on the gas outlet 15c side is mounted on the front end face 17d of the concave groove shape. Can not. Therefore, it is possible to prevent erroneous assembly in which the outlet rectifying plate 17 is attached to the outlet gas flow channel 12c in a state where the vertical direction is wrong.

  Here, there is a possibility that the inlet flow straightening plate 16 is erroneously assembled to the rear outlet gas flow channel 12c, and the outlet straightening plate 17 is erroneously assembled to the front inlet gas flow channel 12a. In this example, the projections 16f and 17f are respectively provided on the inlet straightening plate 16 and the outlet straightening plate 17 mounted along the partition walls 23 and 24 so that the distances from the partition walls 23 and 24 are different. Is formed. Guide grooves 25 and 26 are formed at positions corresponding to these, respectively. Therefore, erroneous assembly in which the inlet flow straightening plate 16 is mounted on the rear side and the outlet flow straightening plate 17 is mounted on the front side can be easily and reliably prevented.

(Measure unit mis-assembly prevention structure)
Next, with reference to FIGS. 2B, 3 and 6, a structure for preventing the measurement unit 15 from being erroneously assembled will be described. FIGS. 6A, 6B, 6C, 6D, and 6E are a plan view, a front view, an outlet side end view, a bottom view, and a state in which the measurement unit 15 is turned upside down, respectively. FIG. The measurement unit mounting portion 12b on the meter case 2 side is formed with a guide groove 30 (measurement unit mounting portion side guide portion) for guiding the mounting of the measurement unit 15. On the side of the measuring unit 15, the guide is guided to the regular mounting position along the guide groove 30 when the front and rear directions are mounted in a correct state, and is regular along the guide groove 30 when mounted in the opposite direction. A pair of protrusions 29a and 29b (measurement unit side guides) are formed to be guided to an erroneous mounting position deviating from the mounting position.

  As shown in FIG. 6, the measurement unit 15 includes a unit case 27 having a rectangular cylindrical shape elongated in the front-rear direction, and a front end opening thereof is a gas inlet 15a, and a rear end opening thereof is a gas outlet 15c. Seal grooves 27a to which seal members 28a and 28b (see FIG. 3) are attached are formed in the outer peripheral surface portion on the gas inlet 15a side and the outer peripheral surface portion on the gas outlet 15c side of the unit case 27, respectively. . The measurement unit 15 is mounted and fixed in rectangular grooves formed on the end surfaces of the front and rear partition walls 23 and 24 on the measurement unit mounting portion 12b side with the front and rear seal members 28a and 28b interposed therebetween. The portion of the measuring unit 15 on the side of the gas inlet 15a is mounted on a rectangular groove-shaped mounting portion formed on the rear end face 16e of the inlet rectifying plate 16, and the portion of the measuring unit 15 on the side of the gas outlet 15c. The portion is mounted on a rectangular groove-shaped mounting portion formed on the front end face 17d of the outlet flow straightening plate 17.

  In the unit case 27 of the measurement unit 15, a rectangular frame plate 29 is attached to a central portion of the top plate portion 27b in the front-rear direction (length direction). Projections 29a, 29b (measurement unit side guides) having a constant thickness and semicircular contours protruding outward in the width direction are formed on both edges in the width direction of the frame plate 29. In this example, the left and right projections 29a and 29b are formed at positions offset by a small distance (eccentricity δ) toward the gas inlet 15a with respect to the center C of the measurement unit 15 in the front-rear direction.

  On the side of the measurement unit mounting portion 12b, a guide groove 30 having a semicircular cross section through which the projections 29a and 29b can be inserted from a direction orthogonal to the bottom opening 4 is formed on the inner peripheral surface 2b of the rear wall of the meter case 2. I have. When the measurement unit 15 is mounted on the measurement unit mounting portion 12b with the front and rear directions correct, one of the protrusions 29b is positioned on the guide groove 30 side. When the measurement unit 15 is mounted on the measurement unit mounting portion 12b in a state where the front and rear directions are reversed, the other protrusion 29a is located on the guide groove 30 side. The measurement unit 15 has a symmetrical shape in the front-rear and left-right directions, and the measurement unit 15 can be mounted on the measurement unit mounting portion 12b even when the front-rear direction is reversed.

  When the measurement unit 15 is mounted in a state where the front and rear directions are correct (the state illustrated in FIG. 6D), the protrusions 29 b are guided by the guide grooves 30, and the measurement unit 15 is positioned at the regular mounting position in the front and rear direction. It is guided and mounted. FIG. 2B shows a state where the measuring unit 15 is mounted at the regular mounting position. In the normal mounting position, the portion of the measuring unit 15 on the gas inlet 15a side engages with the rectangular groove-shaped end face of the partition wall 23 with the seal member 28a interposed therebetween, and the gas The portion on the side of the outlet 15c also engages the rectangular groove-shaped end face of the partition wall 24 with the seal member 28b sandwiched therebetween.

  On the other hand, when the measurement unit 15 is mounted on the measurement unit mounting portion 12b in a state where the front and rear are reversed, the following is performed. As shown in FIG. 6E, in a state in which the projection 29a is positioned and engaged with the guide groove 30, the measuring unit 15 moves with respect to the measuring unit mounting portion 12b as compared with the case where the front and rear directions are correct. Are positioned at a position offset by a distance 2δ in the front-rear direction. In this example, it is positioned at a position offset by a distance 2δ on the front side in the front-rear direction in the measurement unit mounting portion 12b. When the measurement unit 15 is mounted along the guide groove 30 in the case where the front and rear are reversed in this way, the measurement unit 15 is moved to the erroneously assembled position offset by a distance 2δ forward with respect to the normal mounting position. Be attached. In the state of the erroneous assembly position, the seal members 28a and 28b before and after the measurement unit 15 are respectively displaced forward from the end surfaces of the partition walls 23 and 24 on the measurement unit mounting portion 12b side. The operator sees this mounting state and notices that the measuring unit 15 has been incorrectly assembled in a state where the measurement unit 15 is upside down. Thereby, erroneous assembly of the measuring unit 15 is prevented.

(Structure to prevent wrong assembly between the measuring unit and the bottom cover)
Here, in this example, in order to reliably prevent the measurement unit 15 from being erroneously assembled in a state where the measurement unit 15 is reversed, when the measurement unit 15 is assembled in a state where the measurement unit 15 is reversed, the bottom cover 3 is attached to the meter. It is configured such that it cannot be attached to the bottom of the case 2.

  With reference to FIGS. 3, 6 and 7, a structure for preventing erroneous assembly of measurement unit 15 configured between measurement unit 15 and bottom cover 3 will be described. FIG. 7 is a perspective view when the bottom cover 3 is viewed from above.

  First, as shown in FIG. 6, the bottom plate portion 27c of the unit case 27 of the measurement unit 15 has, at the edges on both sides thereof, an arc plate 31 of a constant thickness having a semicircular contour protruding outward in the width direction. It is protruding. Truncated cone-shaped projections 32a, 32b (measurement unit side bottom cover guide) project vertically downward from the center of the back surface of the arc plate 31. The pair of projections 32a and 32b are formed at rotationally symmetric positions with respect to the center of the measurement unit 15 in the front-rear and left-right directions.

  As shown in FIG. 7, the bottom cover 3 has an opening edge 33 in the shape of an elongated rectangular frame as a whole. The opening edge 33 has a contour shape corresponding to the opening edge of the bottom opening 4 of the meter case 2, and is attached to the opening edge 4 a on the meter case 2 side with the seal member 21 interposed therebetween. Inside the opening edge portion 33, a bottom portion 34 having a flattened rectangular contour is formed at a central portion in the long side direction, and on both sides of the bottom portion 34, bottom portions are formed by partition wall portions 35 and 36. Curved bottom portions 37 and 38 are formed, which are separated from 34. In this example, the bottom cover 3 has a symmetrical shape in front, rear, left and right.

  The flat bottom portion 34 functions as a unit holding surface that comes into contact with the measurement unit 15 mounted on the measurement unit mounting portion 12b on the meter case 2 side. The upwardly opened rectangular grooves defined by the upper end surfaces of the partition walls 35 and 36 on both sides sandwich the seal members 28a and 28b and function as a pressing portion that presses the measuring unit 15. The curved bottom portions 37 and 38 on both sides of the bottom portion 34 are portions that define the inlet gas passage 12a and the outlet gas passage 12c with the meter case 2, respectively.

  In the bottom cover 3 having this configuration, hemispherical concave portions 39a and 39b (bottom cover side guide portions) are formed at the corners at both ends in the diagonal direction of the flat bottom portion 34, respectively. Recesses 39a and 39b are formed at positions corresponding to the pair of projections 32a and 32b on the side of measurement unit 15 mounted at the regular mounting position.

  When attaching the bottom cover 3 after attaching the measurement unit 15 to the measurement unit attachment portion 12b on the meter case 2 side, when the measurement unit 15 is attached to the regular attachment position, in other words, when the front and rear directions are correct. When the measurement unit 15 is mounted on the bottom cover 3, the pair of recesses 39a and 39b of the bottom cover 3 attached to the bottom opening 4 of the meter case 2 are located at positions corresponding to the pair of projections 32a and 32b on the measurement unit 15 side. Can be positioned. Therefore, the pair of projections 32a and 32b are inserted into the pair of recesses 39a and 39b, and the bottom cover 3 can be attached to the bottom of the meter case 2.

  On the other hand, when the measuring unit 15 is erroneously assembled in the reverse direction, the pair of protrusions 32a and 32b is offset to the one side in the front-rear direction by the distance 2δ. When the bottom cover 3 is to be mounted, the pair of recesses 39a, 39b cannot be positioned with respect to the pair of projections 32a, 32b, and the bottom portion 34 of the bottom cover 3 hits the projections 32a, 32b. Since the bottom cover 3 hits the projections 32a and 32b and cannot be attached, the operator can know that the measuring unit 15 is erroneously assembled in an upside-down state. Therefore, erroneous assembly of the measurement unit 15 can be easily and reliably prevented.

DESCRIPTION OF SYMBOLS 1 Gas meter 2 Meter case 2a Front wall inner peripheral surface 2b Rear wall inner peripheral surface 2c, 2d Side wall inner peripheral surface 3 Bottom cover 4 Bottom opening 4a Opening edge 5 Gas inlet 6 Gas outlet 7 Liquid crystal display 8 Control unit 11 Upstream gas flow path 11a Communication port 12 Intermediate gas flow path 12a Inlet gas flow path 12b Measurement unit mounting part 12c Outlet gas flow path 13 Downstream gas flow path 14 Gas shut-off valve 15 Measurement unit 15a Gas inlet 15b Unit internal gas flow Road 15c Gas outlet 16 Inlet straightening plate 16a Top plate portion 16b, 16c Side plate portion 16d Front end surface 16e Rear end surface 16f Projection 17 Outlet straightening plate 17a Top plate portion 17b, 17c Side plate portion 17d Front end surface 17e Rear end surface 17f Projection 21 seal member 22 screw 23, 24 partition wall 25, 26 guide groove 27 unit case 27a seal groove 7b Top plate portion 27c Bottom plate portion 28a, 28b Seal member 29 Frame plate 29a, 29b Projection 30 Guide groove 31 Arc plate 32a, 32b Projection 33 Opening edge 34 Bottom portion 35, 36 Wall portion 37, 38 Curved bottom portion 39a, 39b recess

Claims (7)

From the bottom opening of the meter case to the inlet gas flow path, the measurement unit mounting portion and the outlet gas flow path in the internal gas flow path of the meter case, respectively, an inlet rectifying plate, an ultrasonic measurement unit and an outlet rectifier. A plate is mounted, wherein the bottom opening is a structure for preventing incorrect assembly of the gas flow rate measuring component of the gas meter, which is closed by a bottom cover attached to the bottom of the meter case,
In the inlet gas flow path, an inlet gas flow path side guide portion for guiding the mounting of the inlet straightening plate is formed,
The inlet straightening plate is formed with an inlet straightening plate side guide portion that engages with the inlet gas flow channel side guide portion and guides the mounting of the inlet straightening plate to the inlet gas flow channel,
The inlet rectifying plate side guide portion is positioned at a position where the inlet rectifying plate side guide portion engages with the inlet gas flow channel side guide portion only when the inlet rectifying plate is mounted on the inlet gas flow channel with the front and rear directions correct. Is possible,
In the outlet gas flow path, an outlet gas flow path side guide portion for guiding the mounting of the outlet straightening plate is formed,
The outlet straightening plate is formed with an outlet straightening plate side guide portion that engages with the outlet gas flow channel side guide portion and guides the mounting of the outlet straightening plate to the outlet gas flow channel,
The outlet straightening plate side guide portion is positioned at a position where the outlet straightening plate is engaged with the outlet gas flow passage side guide portion only when the outlet straightening plate is mounted on the outlet gas flow passage in a state where the front and rear directions are correct. A structure that prevents erroneous assembly of flow meter parts for gas meters that is possible. In claim 1,
In the measurement unit mounting portion, a unit mounting portion side guide portion for guiding the mounting of the measurement unit is formed,
When the measurement unit is mounted in the front-rear direction in the correct state, the measurement unit guides the measurement unit to a predetermined regular mounting position along the unit-mounting unit-side guide portion, and the front-rear direction is reversed. When mounted in a state, a measurement unit side guide portion is formed along the unit mount portion side guide portion to guide to a wrong mounting position deviating from the regular mounting position. Anti-adhesion structure. In claim 2,
The measurement unit is formed with a measurement unit side bottom cover guide that guides attachment of the bottom cover to the meter case,
The bottom cover is formed with a bottom cover-side guide that engages with the measurement unit-side bottom cover guide and guides attachment of the bottom cover to the bottom.
The bottom cover side guide portion is a flow rate measuring component of a gas meter that can be positioned at a position where the bottom cover side guide portion engages with the measurement unit side bottom cover guide portion only when the measurement unit is mounted at the regular mounting position. Structure to prevent incorrect assembly. In claim 1,
The measurement unit is formed with a measurement unit side bottom cover guide that guides attachment of the bottom cover to the meter case,
The bottom cover is formed with a bottom cover-side guide that engages with the measurement unit-side bottom cover guide and guides attachment of the bottom cover to the bottom.
When the measurement unit is mounted in the measurement unit mounting portion in a state where the front and rear directions are correct, and the mounting position of the measurement unit is a regular mounting position,
The bottom cover side guide portion is a flow rate measuring component of a gas meter that can be positioned at a position where the bottom cover side guide portion engages with the measurement unit side bottom cover guide portion only when the measurement unit is mounted at the regular mounting position. Structure to prevent incorrect assembly. From the bottom opening of the meter case, an ultrasonic measurement unit is mounted on the measurement unit mounting portion in the internal gas flow path of the meter case, and the bottom opening is formed by a bottom cover attached to the bottom of the meter case. A structure for preventing erroneous assembling of a flow rate measuring part of a gas meter which is closed,
In the measurement unit mounting portion, a unit mounting portion side guide portion for guiding the mounting of the measurement unit is formed,
When the measurement unit is mounted in the front-rear direction in the correct state, the measurement unit guides the measurement unit to a predetermined regular mounting position along the unit-mounting unit-side guide portion, and the front-rear direction is reversed. When mounted in a state, a measurement unit side guide portion is formed along the unit mount portion side guide portion to guide to a wrong mounting position deviating from the regular mounting position. Anti-adhesion structure. In claim 5,
The measurement unit is formed with a measurement unit side bottom cover guide that guides attachment of the bottom cover to the meter case,
The bottom cover is formed with a bottom cover-side guide that engages with the measurement unit-side bottom cover guide and guides attachment of the bottom cover to the bottom.
The bottom cover side guide portion is a flow rate measuring component of a gas meter that can be positioned at a position where the bottom cover side guide portion engages with the measurement unit side bottom cover guide portion only when the measurement unit is mounted at the regular mounting position. Structure to prevent incorrect assembly. From the bottom opening of the meter case, an ultrasonic measurement unit is mounted on the measurement unit mounting portion in the internal gas flow path of the meter case, and the bottom opening is formed by a bottom cover attached to the bottom of the meter case. A structure for preventing erroneous assembling of a flow rate measuring part of a gas meter which is closed,
The measurement unit is formed with a measurement unit side bottom cover guide that guides attachment of the bottom cover to the meter case,
The bottom cover is formed with a bottom cover-side guide that engages with the measurement unit-side bottom cover guide and guides attachment of the bottom cover to the bottom.
When the measurement unit is mounted in the measurement unit mounting portion in a state where the front and rear directions are correct, and the mounting position of the measurement unit is a regular mounting position,
The bottom cover side guide portion is a flow rate measuring component of a gas meter that can be positioned at a position where the bottom cover side guide portion engages with the measurement unit side bottom cover guide portion only when the measurement unit is mounted at the regular mounting position. Structure to prevent incorrect assembly.

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