JP6646415B2 - Ultrasonic flow meter - Google Patents

Description

  The present invention relates to an ultrasonic flowmeter that measures the flow rate of a fluid to be measured using ultrasonic waves.

  Conventionally, an ultrasonic flowmeter is configured by arranging a tubular measurement channel portion inside a substantially box-shaped meter case, and transmitting ultrasonic waves to a fluid to be measured flowing through the measurement channel portion. The apparatus is configured to measure the flow rate of the fluid to be measured by utilizing the fact that the propagation time or the propagation speed of the ultrasonic wave changes depending on the flow velocity of the fluid to be measured (for example, gas).

  Here, the gas as the fluid to be measured inevitably contains moisture and impurities (for example, dust mixed during gas production, oil-based impurities generated in a petroleum refining process, and the like). For this reason, when the fluid to be measured flows into the meter case in order to measure the flow rate of the fluid to be measured by the ultrasonic flow meter, moisture and impurities (hereinafter, moisture, etc.) are condensed or adhered inside the meter case. Or

  As described above, the measurement flow path portion is disposed inside the meter case in the ultrasonic flow meter, and is a portion where the measurement fluid flowing into the inside of the meter case flows down, and thus is included in the measurement fluid. In some cases, moisture or the like directly enters the inside of the measurement channel. In addition, since the water and the like entering the inside of the meter case are stored in the inside of the meter case as needed, when the storage amount of the water and the like becomes equal to or more than a predetermined value, the stored water is removed from the measurement flow path section. It is also conceivable that the vehicle may enter the inside of the vehicle. In this way, the moisture or the like that has entered the inside of the measurement channel portion affects the propagation time and the propagation speed of the ultrasonic wave inside the measurement channel portion, or is disposed with respect to the measurement channel portion. In some cases, a malfunction of the pair of ultrasonic vibrators or the like may be caused, so that the measurement accuracy of the flow rate by the ultrasonic flowmeter may be reduced.

  As for the ultrasonic flowmeter, the inventions described in Patent Literature 1 and Patent Literature 2 are known as inventions implemented as measures against moisture in the inside of the meter case. The gas meter described in Patent Document 1 is formed in an airtight structure and has a meter case partitioned into a first chamber and a second chamber by a partition, and a cylindrical gas conduction path (measurement flow) arranged to penetrate the partition. And a pair of ultrasonic vibrators arranged to face each other with a predetermined length in a direction parallel to the gas flow passing through the gas conducting path.

  The gas meter described in Patent Literature 1 has a gas conduction path through which gas flows from the first chamber to the second chamber, in which an end on the first chamber side is located upward and an end on the second chamber side is located downward. And in the meter case in a state inclined with respect to the horizontal direction so as to be positioned at That is, the gas meter arranges the gas conduction path so as to be inclined with respect to the horizontal direction, so that water, grease-based impurities, etc., are positively dropped along the inclination of the gas conduction path by gravity, It is stored in the lower part of two rooms. In other words, the gas meter described in Patent Document 1 prevents a decrease in measurement accuracy due to moisture or the like existing inside the gas passage by preventing water or the like entering the gas passage from flowing out to the outside at an early stage. ing.

  On the other hand, the gas meter described in Patent Literature 2 connects a flow path member having a substantially U-shaped flow path connecting an inflow port to an outflow port, and a space on the inflow side and an outflow side in the flow path member. And a bottom panel member that is attached to the bottom surface of the flow path member and fixes the measurement pipe at a predetermined position inside the flow path member. The ultrasonic wave is propagated to the gas flowing down the inside of the measurement pipe to measure the flow rate of the gas.

  In the gas meter described in Patent Literature 2, a buffer portion is formed on the bottom panel member, and the bottom panel member is sandwiched between a lower central portion of the flow channel member and the buffer portion, so that the inside of the flow channel member is formed. In addition to fixing the measurement tube at a predetermined position, a substantially U-shaped flow path connecting the inflow port and the outflow port is divided into a space located on the inflow side and a space located on the outflow side. The buffer section in Patent Document 2 is connected to a lower portion of the space on the inlet side inside the flow path member at the lower portion of the measurement pipe, and the opening of the buffer section is located below the space on the inlet side. A large opening is provided so that water and the like and gas can move freely between the side portions. Therefore, according to the gas meter described in Patent Literature 2, in addition to the capacity of the lower part in the space on the inflow port side where water can be stored conventionally, the amount of water that can be stored is reduced by the capacity of the buffer unit. Therefore, it is possible to reduce a situation in which the stored moisture or the like enters the inside of the measurement pipe, thereby suppressing a decrease in the measurement accuracy of the flow rate.

JP-A-11-051723 JP 2009-186430 A

  As described above, the moisture and the like inside the meter case are derived from the gas contained in the fluid to be measured. Also, it is assumed that the amount of moisture condensed or attached in the space on the inlet side is larger. For this reason, as in the gas meter described in Patent Literature 2, configuring the space on the inlet side with respect to the measurement pipe to be able to store more moisture than the space on the outflow side requires that moisture such as dew condensation be formed. Considering the amount, it can be considered appropriate.

  However, as in the gas meter described in Patent Document 2, the space on the inlet side with respect to the measurement tube is configured to be larger than the space on the outlet side, and the space on the inlet side and the space on the outlet side are different from each other. When the volume difference of the measured fluid is increased, it is strongly affected by the periodic vibration of the fluid to be measured (that is, the pulsation of the fluid to be measured) inside the pipe to which the gas meter is connected, and the measurement accuracy of the fluid to be measured is reduced. I will. For example, when the volume difference between the space on the inlet side and the space on the outlet side is large, the flow rate of the measurement pipe flowing down from the inlet side to the outlet side due to pulsation of the fluid to be measured, Due to the pulsation, the difference from the flow rate flowing down the measurement pipe from the outlet side to the inlet side becomes large. In this case, although the difference in the flow rate is caused by the pulsation of the fluid to be measured, a problem occurs in which the flow rate of the fluid to be measured is measured due to use.

  The present disclosure has been made in view of the above problems, and relates to an ultrasonic flowmeter that measures the flow rate of a fluid to be measured using ultrasonic waves, and reduces the influence of pulsation of the fluid to be measured on measurement accuracy. And an ultrasonic flowmeter capable of appropriately storing moisture contained in the fluid to be measured.

  To achieve the above object, an ultrasonic flowmeter according to one aspect of the present invention is a meter case having an inlet for a fluid to be measured and an outlet for the fluid to be measured, and is disposed inside the meter case, A flow rate measurement unit that measures the flow rate of the fluid to be measured that passes through the inside of the meter case via the inflow port and the outflow port, and wherein the flow rate measurement unit is configured such that: And a pair of ultrasonic transducers respectively disposed on an upstream side and a downstream side of the flow of the fluid to be measured in the measurement flow channel. The meter case communicates with the inflow port, and has an inlet buffer section partitioned so that the fluid to be measured flowing through the inflow port flows into the inlet section of the measurement flow path section. Connected to the outlet And an outlet buffer section partitioned with a smaller volume than the inlet buffer section so that the fluid to be measured flowing out of the outlet section of the measurement flow path section flows out of the meter case through the outlet port. And a central space formed between the inlet buffer section and the outlet buffer section and penetrated by the measurement channel section, wherein the inlet buffer section includes an inlet section of the measurement channel section and A partition plate that partitions a part of the inlet buffer unit communicating with the inflow port so as to have a volume substantially equal to the outlet buffer unit, and a part of the inlet buffer unit that is partitioned by the partition plate; A buffer space section defined so that the fluid to be measured flowing through the inflow port flows into an inlet section of the measurement flow path section, and a partition plate and a buffer space section below the buffer space section. A storage space that extends toward the central space, and stores moisture contained in the fluid to be measured that has flowed into the inlet buffer, and the partition plate, and the buffer space and the storage And a communication portion that movably communicates the moisture in the buffer space portion with the space portion.

  The ultrasonic flowmeter has an inlet buffer section and an outlet buffer section inside the meter case, which are connected by a measurement flow path section of the flow rate measurement unit, from the inflow port to the outflow port. By transmitting ultrasonic waves from the pair of ultrasonic vibrators to the fluid to be measured flowing in the measurement flow path, the flow rate of the fluid to be measured can be measured. Here, when the fluid to be measured flows in from the inflow port, it flows into the inside of the inlet buffer section, flows into the inside of the measurement flow path section from the entrance section in the measurement flow path section of the flow rate measurement unit, and It flows out of the meter case through an outlet part, an outlet buffer part, and an outlet in the section.

  And in the said ultrasonic flowmeter, the inlet buffer part is divided into the buffer space part and the storage space part by the partition plate, The buffer space part is via the communication part comprised by a partition plate, It communicates with the storage space. Therefore, according to the ultrasonic flowmeter, the water and the like contained in the fluid to be measured flowing into the buffer space in the inlet buffer are stored in the storage space in the inlet buffer via the communication portion. Therefore, it is possible to suppress the entry of moisture and the like into the inside of the measurement flow path portion. According to the ultrasonic flow meter, the storage space in the inlet buffer extends toward the central space below the partition plate and the buffer space, and therefore flows into the inlet buffer. A large amount of water and the like contained in the measured fluid can be stored in the storage space. Further, in the ultrasonic flowmeter, the buffer space in the inlet buffer is partitioned so as to have substantially the same volume as the outlet buffer, and the communication space through which the water in the buffer space communicates movably. It is connected to the storage space. Thereby, according to the ultrasonic flowmeter, the movement of the fluid to be measured relative to the storage space communicated with the fluid through the communicating portion is suppressed along with the pulsation of the fluid to be measured. The volume difference can be reduced, and the influence of the pulsation of the fluid to be measured on the measurement accuracy can be reduced.

  An ultrasonic flowmeter according to another aspect of the present invention is the ultrasonic flowmeter according to claim 1, wherein the communication portion is separated from the inner surface of the inlet buffer portion by a predetermined distance from the inner surface of the inlet buffer portion. It is characterized by being constituted by the edge of the above-mentioned partition plate.

  In the ultrasonic flowmeter, the communication portion includes an inner surface of the inlet buffer portion and an edge of the partition plate separated from the inner surface of the inlet buffer portion by a predetermined distance. Thus, according to the ultrasonic flowmeter, the inlet buffer section can be divided into the buffer space section and the storage space section while forming the communication section with a simpler and more specific configuration. Thereby, the ultrasonic flowmeter realizes a configuration capable of appropriately storing the water contained in the measured fluid in the storage space while reducing the influence of the pulsation of the measured fluid on the measurement accuracy. obtain.

  An ultrasonic flowmeter according to another aspect of the present invention is the ultrasonic flowmeter according to claim 1, wherein the partition plate is provided at an edge of the partition plate that comes into contact with an inner surface of the inlet buffer unit. A groove extending in the thickness direction of the partition plate and having a concave shape, wherein the communication portion is formed by an inner surface of the inlet buffer portion and the groove formed at an edge of the partition plate. It is characterized by having.

  In the ultrasonic flowmeter, the communication portion may be configured such that an edge of the partition plate is brought into contact with an inner surface of the inlet buffer portion, and the groove formed on an edge of the partition plate; And the inner surface of the part. Therefore, according to the ultrasonic flow meter, the inlet buffer section is partitioned into the buffer space section and the storage space section by forming the communication section by bringing the edge of the partition plate into contact with the inner surface of the inlet buffer section. be able to. Thereby, the ultrasonic flowmeter realizes a configuration capable of appropriately storing the water contained in the measured fluid in the storage space while reducing the influence of the pulsation of the measured fluid on the measurement accuracy. obtain.

  An ultrasonic flowmeter according to another aspect of the present invention is the ultrasonic flowmeter according to any one of claims 1 to 3, wherein the partition plate is formed separately from the meter case. And a portion of the inlet buffer portion communicating with the inflow port is attached to the inlet buffer portion such that the inlet buffer portion has substantially the same volume as the outlet buffer portion.

  In the ultrasonic flowmeter, the partition plate is formed separately from the meter case, and a part of the inlet buffer communicating with the inlet has a volume substantially equal to the outlet buffer. Is attached to the entrance buffer section. That is, according to the ultrasonic flowmeter, the inlet buffer portion is buffered by arranging a separately formed partition plate for the meter case having the inlet buffer portion, the outlet buffer portion, and the central space portion. It can be divided into a space part and a storage space part. That is, the ultrasonic flowmeter uses a partition plate formed separately to reduce the influence of the pulsation of the fluid to be measured on the measurement accuracy and to remove the water contained in the fluid to be measured from the storage space portion. A configuration that can be appropriately stored inside can be realized.

  An ultrasonic flowmeter according to another aspect of the present invention is the ultrasonic flowmeter according to claim 4, wherein the communication portion is formed by a through-hole penetrating the partition plate in a plate thickness direction. It is characterized by.

  In the ultrasonic flowmeter, the communication portion is formed by a through hole that penetrates the partition plate in a plate thickness direction. When the partition plate is formed separately, the degree of freedom regarding the formation of the through hole (for example, the position, size, and shape of the through hole) is different from the case where the partition plate is formed integrally with the meter case. Etc.). Therefore, according to the ultrasonic flowmeter, the buffer space portion and the storage space portion can be communicated with each other by the communication portion formed of the desired through-hole, whereby the pulsation of the fluid to be measured affects the measurement accuracy. It is possible to realize a configuration that can appropriately store the water contained in the fluid to be measured in the storage space while reducing the influence.

FIG. 2 is an exploded perspective view illustrating a schematic configuration of the ultrasonic flowmeter according to the first embodiment. It is an external appearance perspective view of the meter housing concerning a 1st embodiment. FIG. 2 is an external perspective view of a rear cover according to the first embodiment. FIG. 4 is a front view showing the ultrasonic flowmeter with a rear cover removed. It is a principal part sectional view which shows the internal structure of a flow measurement unit. FIG. 4 is a vertical sectional view showing the internal configuration of the entrance buffer unit according to the first embodiment. It is a horizontal sectional view showing the internal composition of the ultrasonic flowmeter concerning a 1st embodiment. It is an external appearance perspective view of the meter housing | casing which concerns on 2nd Embodiment. It is a vertical sectional view showing the internal composition of the entrance buffer part concerning a 2nd embodiment. It is a horizontal sectional view showing the internal composition of the ultrasonic flowmeter concerning a 2nd embodiment. It is an appearance perspective view of a meter case concerning a 3rd embodiment. It is an external appearance perspective view of the partition plate concerning a 3rd embodiment. It is a vertical sectional view showing the internal composition of the entrance buffer part concerning a 3rd embodiment. It is a horizontal sectional view showing the internal composition of the ultrasonic flowmeter concerning a 3rd embodiment.

(1st Embodiment)
Hereinafter, an embodiment (first embodiment) in which the ultrasonic flowmeter according to the present invention is embodied in the ultrasonic flowmeter 1 will be described in detail with reference to the drawings. In the following description, the front-rear direction, the up-down direction, and the left-right direction will be defined when the ultrasonic flowmeter 1 is used. That is, the side where the user using the ultrasonic flowmeter 1 is located is defined as the front side, and the opposite direction is defined as the rear side. The surface of the ultrasonic flowmeter 1 where the inflow port 11 and the outflow port 12 are disposed is defined as an upper side, and the opposite direction is defined as a lower side. Then, the left-right direction is defined with reference to the ultrasonic flow meter 1 in a state following the front-rear direction and the up-down direction defined as described above.

(Schematic configuration of ultrasonic flow meter)
First, the configuration of the ultrasonic flowmeter 1 according to the first embodiment will be described with reference to FIGS. The ultrasonic flow meter 1 according to the first embodiment is a fuel gas meter that measures the flow rate of a fuel gas (for example, a city gas or an LP gas) that is an example of a fluid to be measured. The flow rate measuring unit 50 is provided inside the connected meter case 5.

  As shown in FIGS. 1 to 3, the meter case 5 includes a meter housing 10 formed in a substantially rectangular parallelepiped shape whose rear side is open, and a rear cover 20 having a plurality of recesses recessed by a predetermined depth on the front side. The rear case 20 is screwed to the rear side of the meter housing 10 so that the inside of the meter case 5 is kept airtight.

  An inlet 11 and an outlet 12 are formed at both ends in the left-right direction on the upper surface of the meter housing 10, and the fuel gas pipe 2 is airtight with respect to the inlet 11 and the outlet 12, respectively. Connected to. The inflow port 11 and the outflow port 12 communicate with a space formed inside the meter case 5 (an inlet buffer 30, a central space 40, and an outlet buffer 45, which will be described later). Therefore, in the ultrasonic flowmeter 1, the fuel gas is supplied to the inside of the meter case 5 through the inflow port 11 to which the pipe 2 is connected, and from the inside of the meter case 5 through the outflow port 12. It is discharged to the pipe 2 extending to the outside of the case 5 (see FIG. 4 and the like).

  The flow rate measuring unit 50 is disposed inside the airtightly held meter case 5, and uses the pair of ultrasonic vibrators 52A and 52B (see FIG. 5) to form the inflow port 11. The flow rate of the fuel gas passing through the inside of the meter case 5 from the outlet 12 to the outlet 12 is measured. As shown in FIGS. 1 and 4 and the like, the flow rate measuring unit 50 is configured so that the measurement channel portion 51 formed in a rectangular cylindrical shape extends along the left-right direction of the meter housing 10. Located inside.

(Schematic configuration of meter case)
Next, a schematic configuration of the meter case 5 will be described in detail with reference to the drawings. As described above, the meter case 5 is configured to include the meter housing 10 and the rear cover 20, and the inside of the meter case 5 includes the inlet buffer 30, the central space 40, and the outlet buffer 45. Are formed. Then, the inlet buffer section 30, the central space section 40, and the outlet buffer section 45 are arranged such that the flow rate measuring unit 50 to which the O-ring is attached is disposed inside the meter case 5 and the rear side of the meter housing 10 By screwing the rear cover 20 to each other, each is kept airtight.

  The meter housing 10 is made of a metal material such as aluminum or an aluminum alloy. As shown in FIGS. 1 and 2, the inlet buffer 30, the central space 40, and the outlet buffer 45 are Are formed so as to be arranged in order from the right end side to the left end side of the meter housing 10.

  The inlet buffer section 30 is a space defined by a partition wall 17A of the meter housing 10, a partition wall 21A of the rear cover 20, and the like inside the meter case 5, and is connected to the inflow port 11 through an opening 15 described later. Communicating. As shown in FIGS. 1, 2, and 4, the inlet buffer portion 30 is formed to extend vertically in a right portion inside the meter case 5, and to form a lower portion inside the meter case 5. In the figure, the right side inside the meter case 5 extends leftward. That is, the inlet buffer section 30 is partitioned inside the meter case 5 so as to extend in an inverted L shape along the right side surface and the lower surface of the meter case 5.

  The inlet buffer section 30 extends in the left-right direction at the buffer space section 31 located at the upper portion on the right side of the meter case 5 and at the lower portion of the meter case 5 by the partition plate 33 disposed therein. It is partitioned into a storage space 32 (see FIGS. 1, 2 and 4). The detailed configuration of the entrance buffer unit 30 will be described later in detail with reference to the drawings.

  As shown in FIGS. 1, 2, 4, etc., the partition wall 17 </ b> A is formed at a predetermined distance from the right end of the meter housing 10 in the upper part of the meter housing 10. From the front wall surface portion to the rear end portion in the inside. A concave portion 18A is formed at a predetermined position of the partition wall 17A extending in the up-down direction, and the measurement flow path 51 of the flow rate measuring unit 50 is fitted into the concave portion 18A.

  Specifically, the concave portion 18A is slightly larger than the outer shape of the measurement flow path portion 51 of the flow rate measuring unit 50 forward from the rear end of the partition wall 17A (for example, outside the outer shape of the measurement flow path portion 51). (About 1 mm to about 3 mm larger). Therefore, an O-ring can be attached between the ribs 55 of the measurement flow path unit 51 in the flow rate measurement unit 50 in the concave portion 18A, and a portion where the O-ring of the measurement flow path unit 51 is attached can be disposed. The airtightness between the outer peripheral surface of the measurement flow path 51 and the recess 18A can be increased by the ring.

  In the upper part of the meter housing 10, the dimension of the inlet buffer section 30 in the left-right direction (that is, the distance from the right side surface of the meter case 5 to the partition wall 17 </ b> A) is determined in the measurement flow path section 51 of the flow rate measurement unit 50. It is formed so as to be longer by a predetermined distance (for example, about 10 mm) than the distance from each rib 55 to the inlet portion 51A. Therefore, in the upper part of the inlet buffer section 30 (that is, above the partition plate 33), the inlet section 51A of the measurement flow path section 51 is disposed so as to project from the partition wall 17A to the inside of the inlet buffer section 30. (See FIG. 4).

  The central space section 40 is located between the inlet buffer section 30 and the outlet buffer section 45 in the left-right direction in the upper part of the meter housing 10 and is partitioned as a substantially box-shaped space. That is, the central space portion 40 is located between the partition wall 17A and the partition wall 17B inside the meter housing 10. The dimension of the central space 40 in the left-right direction (that is, the distance between the partition wall 17A and the partition wall 17B) is slightly longer than the length of the circuit case 56 in the left-right direction of the flow rate measurement unit 50 (for example, (About 6 mm longer).

  The vertical height of the central space 40 (the vertical height between the partition wall 17A and the partition wall 17B of the meter housing 10) is between the ribs 55 of the measurement flow path unit 51 of the flow rate measurement unit 50. When the O-rings of the measurement flow path 51 are provided in the recesses 18A and 18B respectively, the circuit case 56 is formed to have a height that allows the circuit case 56 to be inserted. I have. When the flow rate measuring unit 50 is disposed inside the meter housing 10, the central space 40 includes a central portion of the flow rate measuring unit 50 sandwiched between the circuit case 56 and the ribs 55 of the measurement flow path 51. (See FIG. 4).

  An external terminal (not shown) is hermetically attached to the front wall surface of the central space 40, and is electrically connected to a measurement board 57 disposed inside the circuit case 56. I have. Since the external terminal is also electrically connected to a control board (not shown) that controls the ultrasonic flowmeter 1, the measured flow rate of the fuel gas output from the measurement circuit of the measurement board 57 To the control board.

  The outlet buffer portion 45 is a space defined in a substantially box-like shape by the partition wall 17B of the meter housing 10, the partition wall 21B of the rear cover 20, and the like on the upper part of the meter case 5, and the left side inside the meter case 5. It is located in. The outlet buffer unit 45 communicates with the outside of the meter housing 10 via the outlet 12.

  The partition wall 17B is formed at a predetermined distance (same as the above-described predetermined distance for the partition wall 17A) from the left end of the meter housing 10 in the upper portion of the meter housing 10. (See FIG. 1, FIG. 2, FIG. 4 and the like). That is, in the upper part of the meter housing 10, the cross-sectional area of the inlet buffer unit 30 in the horizontal direction (that is, the front-rear direction and the left-right direction) is equal to the cross-sectional area of the outlet buffer unit 45 in the horizontal direction. ing.

  As shown in FIGS. 1, 2, 4, etc., a concave portion 18 </ b> B is formed at a predetermined position of the partition wall 17 </ b> B extending in the vertical direction. 51 is fitted. In the vertical direction of the meter case 5, the formation position of the recess 18B in the partition wall 17B is formed so as to be equal to the formation position of the recess 18A in the partition wall 17A. Therefore, inside the meter case 5 of the ultrasonic flowmeter 1, the flow measurement unit 50 is arranged so that the measurement flow path 51 is substantially horizontal (see FIG. 4).

  The concave portion 18B is slightly larger than the outer shape of the measurement flow path portion 51 of the flow measurement unit 50 forward from the rear end of the partition wall 17B (for example, about 1 mm outward from the outer shape of the measurement flow path section 51). (About 3 mm larger). Therefore, in the concave portion 18B, an O-ring can be attached between the ribs 55 of the measurement flow path unit 51 in the flow rate measurement unit 50, and a portion where the O-ring of the measurement flow path unit 51 is attached can be provided. The airtightness between the outer peripheral surface of the measurement flow path portion 51 and the concave portion 18B can be increased by the ring.

  In the upper part of the meter housing 10, the dimension of the outlet buffer 45 in the left-right direction (that is, the distance from the left side surface of the meter case 5 to the partition wall 17 </ b> B) is determined by It is formed to be longer by a predetermined distance (for example, about 10 mm) than the distance from each rib 55 to the outlet 51B. Therefore, as shown in FIG. 4, inside the outlet buffer section 45, the outlet section 51B of the measurement flow path section 51 is disposed so as to project from the partition wall 17B to the inside of the outlet buffer section 45.

  As described above, the inlet 51A of the measurement channel 51 is located inside the inlet buffer 30, and the outlet 51B of the measurement channel 51 is located inside the outlet buffer 45. Therefore, the inlet buffer section 30 and the outlet buffer section 45 are communicated with each other by the substantially rectangular measurement flow path section 51 whose cross section is long in the vertical direction.

  As shown in FIG. 6, inside the meter case 5, the inflow path 13 is formed to extend from the inflow port 11 in the vertical direction of the meter housing 10. The inflow path 13 is formed along the front wall surface of the inlet buffer section 30, and a substantially rectangular parallelepiped inflow chamber 14 is adjacent to the lower end of the inflow path 13 on the front side of the inlet buffer section 30. It is formed.

  As shown in FIGS. 1, 2, and 4, an opening 15 having a circular cross section is formed in the front wall surface of the inlet buffer 30, and the inlet buffer 30 and the end of the inflow passage 13 are formed. It communicates with the inflow chamber 14 constituting a part. The opening 15 is formed such that the center of the opening is orthogonal to the axis of the measurement flow path 51 provided so as to protrude into the inlet buffer 30.

  A shut-off valve (not shown) is disposed inside the inflow chamber 14 at a position facing the opening 15 formed on the front wall surface of the inlet buffer 30, so that the opening 15 can be closed. Have been. The shutoff valve is electrically connected to a control board (not shown), and is controlled to close the opening 15 when an abnormality occurs in the supply gas flow rate or the like. Accordingly, when an abnormality occurs in the supply gas flow rate or the like, the ultrasonic flow meter 1 can forcibly shut off the flow of the fuel gas to the inlet buffer unit 30 and stop the supply of the fuel gas. Is possible.

  The ultrasonic flowmeter 1 is provided with a control board (not shown), and the control board has a control unit including a microcomputer and the like. The control unit is electrically connected to an external terminal electrically connected to the measurement circuit of the flow rate measurement unit 50, a shutoff valve, and the like. The control unit detects an abnormality in the supply gas flow rate or the like based on the flow rate measurement value of the fuel gas output from the measurement board 57, and sets the shutoff valve when the abnormality is a predetermined gas shutoff target. By driving, the opening 15 is closed and the supply of the fuel gas is stopped. Further, the control unit is configured to be able to output the measured value of the flow rate of the fuel gas output from the measurement board 57 to an external personal computer (not shown) or the like.

  As shown in FIGS. 1 and 3, the rear cover 20 is made of a metal material such as aluminum or an aluminum alloy, and is fixed to the meter housing 10 by being screwed to the rear side of the meter housing 10. Is done. Concave portions are formed on the front surface of the rear cover 20 at three positions corresponding to the upper portion (corresponding to a buffer space portion 31 described later), the central space portion 40, and the outlet buffer portion 45 of the meter housing 10. ing.

  As illustrated in FIG. 3, a partition wall 21 </ b> A and a partition wall 21 </ b> B are formed on the front side of the rear cover 20 so as to be partitioned into three concave portions. The partition wall 21A is formed on the front side of the rear cover 20 at a position facing the partition wall 17A of the meter housing 10, and stands upright from the rear wall surface to the front end of the rear cover 20. Similarly, the partition wall 21B is formed on the front side of the rear cover 20 at a position facing the partition wall 17B of the meter housing 10, and stands upright from the rear wall surface to the front end of the rear cover 20.

(Schematic configuration of flow measurement unit)
Subsequently, a schematic configuration of the flow rate measurement unit 50 disposed inside the meter case 5 will be described in detail with reference to the drawings. As shown in FIG. 4, the flow rate measurement unit 50 is formed inside the meter case 5, a measurement flow path portion 51 functioning as a fuel gas flow path, and an upper portion in the longitudinal center of the measurement flow path portion 51. And a circuit case 56. The measurement flow path unit 51 is formed in a tubular shape having a rectangular flow path cross section that is long in the up-down direction.

  As shown in FIG. 5, an ultrasonic transducer 52A and an ultrasonic transducer 52B are arranged on the upper surface side of the measurement flow path 51 in a circuit case 56 located at a central portion in the longitudinal direction of the measurement flow path 51. Have been. The ultrasonic vibrator 52A is disposed on the upper surface of the measurement flow path unit 51 on the upstream side in the fuel gas flow direction (hereinafter, the gas flow-down direction F). Is disposed on the downstream side in the gas flowing direction F on one side.

  The ultrasonic wave output from one of the ultrasonic vibrator 52A and the ultrasonic vibrator 52B is reflected on the facing surface (that is, the lower surface) of the measurement flow path 51, and the ultrasonic vibrator 52A and the ultrasonic vibrator It reaches the other side of the sound wave oscillator 52B. Therefore, an ultrasonic wave propagation path 53 is formed inside the measurement flow path unit 51 in the flow rate measurement unit 50, and the propagation path 53 passes through the ultrasonic wave propagation path via the facing surface (lower surface) of the measurement flow path unit 51. It forms a V-shape connecting the transducer 52A and the ultrasonic transducer 52B.

  A measurement board 57 is provided above the ultrasonic oscillators 52A and 52B inside the circuit case 56, and each of the ultrasonic oscillators 52A and the ultrasonic oscillator is provided on the measurement board 57. A measurement circuit to which 52B is electrically connected is formed. That is, the measurement board 57 is configured to calculate and output a flow rate measurement value of a fluid to be measured such as a fuel gas using a measurement circuit.

  As shown in FIGS. 1 and 4, an inlet 51 </ b> A is formed at one end of the measurement channel 51, and an outlet 51 </ b> B is formed at the other end of the measurement channel 51. . The inlet portion 51A and the outlet portion 51B of the measurement flow path portion 51 are formed into curved surfaces whose inner peripheral surfaces smoothly spread outward.

  Inside the measurement flow path 51, a plurality of (for example, five) flow dividing plates 54 are provided below the ultrasonic vibrators 52A and 52B (see FIG. 5). The plurality of flow dividing plates 54 are parallel to the long side of the measurement flow path section 51 in a state where they are substantially equally spaced in the short side direction in the flow path cross section of the measurement flow path section 51 (ie, It is arranged to extend in the left-right direction). That is, each of the flow dividing plates 54 is provided inside the measurement flow path 51 so as to be parallel to a plane including the ultrasonic wave propagation path 53 between the ultrasonic transducers 52A and 52B, It extends so as to be parallel to the flowing direction F. Thus, the flow of the fuel gas inside the measurement flow path 51 can be stabilized by the respective flow dividing plates 54.

  Further, two rows of ribs 55 are provided upright on the outer circumference of the measurement flow path unit 51 in the flow rate measurement unit 50 over the entire circumference. The rib 55 is used when an O-ring is attached, and has a function of maintaining airtightness in an outer peripheral portion of the measurement flow path 51 by an O-ring formed of rubber or the like having elasticity.

(Flow of fuel gas in ultrasonic flowmeter)
The flow of the fuel gas in the ultrasonic flowmeter 1 configured as described above will be described in detail with reference to the drawings. As shown in FIGS. 1 to 7, the fuel gas is supplied to the ultrasonic flowmeter 1 via a pipe 2 connected to an inlet 11. The fuel gas that has flowed into the inflow port 11 flows into an inflow chamber 14 that forms the lower end of the inflow path 13 through an inflow path 13 that extends along the vertical direction of the meter housing 10. Then, inside the inflow chamber 14, the fuel gas flows so as to be bent substantially at right angles to the gas flowing direction F inside the inflow passage 13, and flows into the inside of the inlet buffer 30 through the opening 15.

  Then, when the fuel gas flows into the inside of the inlet buffer unit 30 through the opening 15, the fuel gas flows along the inner surface of the inlet buffer unit 30 formed by the meter housing 10 and the rear cover 20. Flows into the inlet portion 51A of the measurement flow path portion 51 located inside (see FIGS. 4 and 6).

  As shown in FIGS. 4 and 5, when the fuel gas flows from the inlet portion 51 </ b> A into the inside of the measurement flow passage portion 51, an outlet communicating with the outlet buffer portion 45 along the inner wall surface of the measurement flow passage portion 51. It flows to the unit 51B. The ultrasonic flowmeter 1 transmits ultrasonic waves to the inside of the measurement flow path 51 through which the fuel gas flows from the inlet 51A to the outlet 51B by using the ultrasonic oscillators 52A and 52B. By measuring the propagation time and the like, the flow rate of the fuel gas in the measurement flow path 51 can be measured.

  Thereafter, the fuel gas is discharged from the outlet 51B of the measurement flow path 51 into the outlet buffer 45. As shown in FIGS. 2 and 4, since the outlet buffer 45 is connected to the pipe 2 via the outlet 12, the fuel gas flows from the outlet 51 </ b> B of the measurement flow path 51 to the outlet buffer 45. After being discharged, it flows to the outside of the ultrasonic flowmeter 1 through the outlet 12 and the pipe 2.

(Configuration of the entrance buffer unit in the first embodiment)
Here, the configuration of the inlet buffer unit 30 in the ultrasonic flowmeter 1 according to the first embodiment will be described in detail with reference to FIGS. As described above, the entrance buffer unit 30 is partitioned inside the meter case 5 so as to extend in an inverted L-shape along the right side surface and the lower surface of the meter case 5. , A buffer space portion 31 located along the right side in the upper portion of the meter case 5 and a storage space portion 32 extending from the right portion to the left side in the lower portion of the meter case 5. It is partitioned.

  As shown in FIGS. 1, 2, 6, etc., the partition plate 33 is formed in a plate shape extending rearward from the front wall surface inside the entrance buffer unit 30, and stands upright with respect to the front wall surface. Has been established. The partition plate 33 is provided upright at a distance equal to the vertical dimension of the outlet buffer unit 45 at a position separated from the upper surface of the inlet buffer unit 30. The portion located below the partition plate 33 in the inlet buffer portion 30 is referred to as a storage space portion 32.

  Further, the dimension from the front wall surface of the entrance buffer unit 30 to the rear edge of the partition plate 33 is slightly shorter than the dimension from the front wall surface of the entrance buffer unit 30 to the rear end of the partition wall 17A (for example, 1). , 2 mm). Therefore, even when the rear cover 20 is screwed to the meter housing 10, the rear edge of the partition plate 33 is located at a position separated from the front surface of the rear cover 20 by a predetermined dimension (FIG. 6). , FIG. 7). That is, the buffer space portion 31 and the storage space portion 32 communicate with each other via the communication portion 35 as a gap generated between the front surface of the rear cover 20 and the rear edge of the partition plate 33.

  The buffer space portion 31 is a space defined in a substantially box shape by the partition wall 17A of the meter housing 10, the partition wall 21A of the rear cover 20, and the partition plate 33 in the upper portion of the meter case 5. 5 is located on the right side. As shown in FIG. 4 and the like, the above-mentioned opening 15 is formed in the front wall surface inside the buffer space 31. Therefore, the buffer space 31 communicates with the pipe 2 extending outside the meter housing 10 via the inflow port 11, the inflow path 13, and the opening 15 (see FIG. 6).

  Further, the concave portion 18A is formed in the partition wall 17A constituting the buffer space portion 31 and holds the measurement flow channel portion 51 of the flow rate measurement unit 50. Therefore, the inlet portion 51A of the measurement flow channel portion 51 is , Are located inside the buffer space 31. That is, the buffer space section 31 is formed in a rectangular cylindrical shape, and communicates with the outlet buffer section 45 via the measurement flow path section 51 disposed so as to penetrate the central space section 40 (FIG. 4). reference). Therefore, when the fuel gas flows into the buffer space 31 of the inlet buffer 30 via the opening 15, the fuel gas flows from the inlet 51 </ b> A located in the buffer space 31 to the inside of the measurement flow path 51 through the outlet buffer. 45.

  As described above, the cross-sectional area in the horizontal direction of the inlet buffer section 30 (that is, the buffer space section 31) in the upper portion of the meter housing 10 is equal to the cross-sectional area in the horizontal direction of the outlet buffer section 45. Have been. The partition plate 33 constituting the lower surface of the buffer space portion 31 is provided upright at a distance equal to the vertical dimension of the outlet buffer portion 45 at a distance from the upper surface of the inlet buffer portion 30. Therefore, the buffer space portion 31 according to the first embodiment has a box shape having a volume substantially equal to that of the outlet buffer portion 45.

  The storage space part 32 is a part of the entrance buffer part 30 and is a space partitioned into a substantially box shape below the buffer space part 31 and the partition plate 33. The storage space 32 stores, via the communication portion 35, moisture and the like contained in the fuel gas flowing into the buffer space 31 which is a part of the inlet buffer 30. The storage space 32 extends from below the buffer space 31 to below the central space 40 and the outlet buffer 45 in the lower part of the meter case 5. It is widely used to store a large amount of water and the like contained in fuel gas.

  The communication portion 35 is formed by a gap generated between the front surface of the rear cover 20 and the rear edge of the partition plate 33 when the rear cover 20 is fixed to the rear surface of the meter housing 10 by screwing. In addition, the inside of the buffer space 31 and the inside of the storage space 32 communicate with each other such that water and the like contained in the fuel gas can move. Therefore, according to the inlet buffer section 30, the water and the like flowing into the buffer space section 31 of the inlet buffer section 30 can flow into the storage space section 32 through the communication section 35 together with the fuel gas. Thus, water and the like can be stored in the storage space 32.

  The opening area of the communication portion 35 (that is, the size of the gap formed between the front surface of the rear cover 20 and the rear end edge of the partition plate 33) is determined by the measurement flow path portion 51 located inside the buffer space portion 31. Is formed sufficiently smaller than the opening area of the entrance portion 51A. The opening area of the communication portion 35 is, for example, large enough that the flow of the fuel gas generated due to the pulsation of the fuel gas does not reach the storage space portion 32 from the buffer space portion 31 through the communication portion 35.

(Movement of fuel gas and moisture inside the inlet buffer)
Subsequently, the movement of the fuel gas inside the inlet buffer unit 30 in the ultrasonic flowmeter 1 configured as described above will be described in detail with reference to the drawings. When the fuel gas flows from the inflow port 11 to which the pipe 2 is connected, the fuel gas flows through the inflow path 13 and the opening 15 into the inside of the buffer space 31 in the inlet buffer section 30.

  As described above, the inside of the buffer space 31 communicates with the communication section 35 and the inlet 51A of the measurement flow path 51 of the flow rate measurement unit 50 via the communication section 35 and the inlet 51A of the measurement flow path 51. Since the opening area is sufficiently larger than the opening area of the communication part 35, the fuel gas flowing into the buffer space part 31 flows out of the inlet buffer part 30 through the inlet part 51 </ b> A of the measurement flow path part 51. (See FIGS. 4 and 6).

  Here, a case where a small amount of fuel gas flows into the buffer space 31 due to the pulsation of the fuel gas will be described. As described above, the opening area of the communication section 35 is sufficiently smaller than the opening area of the inlet section 51A in the measurement flow path section 51. Therefore, the fuel gas flowing with the pulsation hardly flows to the storage space 32 through the communication portion 35, and flows from the buffer space 31 of the inlet buffer 30 to the measurement flow passage of the flow measurement unit 50. It flows to the outlet buffer unit 45 via 51. The buffer space 31 of the inlet buffer 30 is partitioned into a substantially box shape having a volume substantially equal to that of the outlet buffer 45. Therefore, according to the ultrasonic flowmeter 1, the volume difference between the buffer space 31 and the outlet buffer 45 can be reduced, and the influence of the pulsation of the fuel gas on the measurement accuracy of the ultrasonic flowmeter 1 is reduced. be able to.

  Next, the movement of moisture and the like inside the inlet buffer unit 30 will be described in detail with reference to the drawings. As described above, the fuel gas inevitably contains moisture, dust mixed during gas production, and impurities such as oil-based impurities generated in a petroleum refining process. Therefore, the fuel gas supplied through the pipe 2 and the inlet 11 flows into the inlet buffer 30 through the opening 15 while containing moisture and the like.

  In the ultrasonic flowmeter 1, the flow measurement unit 50 has a relative position in the ultrasonic flowmeter 1 by fitting the measurement flow path 51 into the concave portions 18 </ b> A and 18 </ b> B formed in the meter housing 10. Positioning is done. As shown in FIGS. 4 and 5, inside the buffer space 31, the inlet 51 </ b> A of the measurement flow path unit 51 in the flow rate measurement unit 50 is closer to the opening 15 formed on the front wall surface of the inlet buffer 30. Are also arranged upward.

  Accordingly, in the process of flowing from the opening 15 of the buffer space 31 to the inlet 51A of the measurement flow path 51 located above the same, gravity acts on the moisture and the like contained in the fuel gas. Due to the action of the gravity, the water and the like contained in the fuel gas are stored in the lower part of the inlet buffer 30 without reaching the inlet 51A of the measurement flow path 51, and the communication part 35 Then, the water flows down in the water movement direction W and is stored in the storage space 32 (see FIG. 5).

  As described above, according to the ultrasonic flow meter 1 according to the first embodiment, the water and the like contained in the fuel gas flowing into the buffer space 31 of the inlet buffer unit 30 are transferred to the inlet buffer 30 through the communication unit 35. It can be stored inside the storage space part 32 in the buffer part 30, so that entry of moisture and the like into the inside of the measurement flow path part 51 in the flow rate measurement unit 50 can be suppressed. According to the ultrasonic flowmeter 1, the storage space 32 in the inlet buffer 30 is located below the central space 40 and the outlet buffer 45 below the buffer space 31 and the partition plate 33. Due to the extension, a large amount of water and the like contained in the fuel gas flowing into the inlet buffer section 30 can be stored inside the storage space section 32.

  As described above, in the ultrasonic flow meter 1 according to the first embodiment, the inlet buffer unit 30 and the outlet buffer unit 45 inside the meter case 5 are connected by the measurement flow path unit 51 of the flow measurement unit 50. And a pair of ultrasonic vibrators 52A and 52B with respect to the fuel gas flowing through the inside of the measurement flow path 51 from the inflow port 11 to the outflow port 12. By transmitting the ultrasonic waves by the above, the flow rate of the fuel gas can be measured. As shown in FIG. 4 and the like, when the fuel gas flows from the inflow port 11, it flows into the inside of the inlet buffer section 30, and the fuel gas flows from the inlet section 51 </ b> A of the measurement flow path section 51 of the flow rate measurement unit 50 to the measurement flow path section. 51, and flows out of the meter case 5 through the outlet 51B, the outlet buffer 45, and the outlet 12 in the measurement flow path 51.

  As shown in FIGS. 6 and 7, in the ultrasonic flowmeter 1, the inlet buffer 30 is partitioned into a buffer space 31 and a storage space 32 by a partition plate 33. Communicates with the storage space 32 via a communication portion 35 formed by a partition plate 33. Therefore, according to the ultrasonic flowmeter 1, the moisture and the like contained in the fuel gas flowing into the buffer space 31 in the inlet buffer 30 are transferred to the storage space in the inlet buffer 30 via the communication portion 35. 32, so that entry of moisture and the like into the inside of the measurement flow path 51 can be suppressed (see FIG. 6). According to the ultrasonic flowmeter 1, the storage space 32 in the inlet buffer 30 is located below the central space 40 and the outlet buffer 45 below the buffer space 31 and the partition plate 33. Due to the extension, a large amount of water and the like contained in the fuel gas flowing into the inlet buffer section 30 can be stored inside the storage space section 32.

  Further, in the ultrasonic flowmeter 1, as shown in FIG. 2 and the like, the buffer space portion 31 in the inlet buffer portion 30 is partitioned so as to have substantially the same volume as the outlet buffer portion 45. The water in the portion 31 is communicatively connected to the storage space 32 by a communication portion 35 that movably communicates therewith. Thus, according to the ultrasonic flowmeter 1, the fuel gas pulsation suppresses the movement of the fuel gas to the storage space 32 communicated through the communication portion 35 with the pulsation of the fuel gas. The difference in volume of the part 45 can be reduced, and the influence of the pulsation of the fuel gas on the measurement accuracy of the ultrasonic flowmeter 1 can be reduced.

  In the first embodiment, the communication portion 35 is formed by the front surface of the rear cover 20 that forms the inner surface of the entrance buffer portion 30 and the rear edge of the partition plate 33 separated from the front surface of the rear cover 20 by a predetermined distance. (See FIGS. 6 and 7). Thus, according to the ultrasonic flowmeter 1, the inlet buffer 30 can be partitioned into the buffer space 31 and the storage space 32 while the communication unit 35 is configured with a simpler and more specific configuration. Thereby, the ultrasonic flowmeter 1 appropriately stores the water contained in the fuel gas in the storage space 32 while reducing the influence of the pulsation of the fuel gas on the measurement accuracy of the ultrasonic flowmeter 1. Possible configurations can be realized.

(2nd Embodiment)
Next, the configuration of the ultrasonic flowmeter 1 according to an embodiment (second embodiment) different from the above-described first embodiment will be described in detail with reference to FIGS. The ultrasonic flowmeter 1 according to the second embodiment has the same configuration as that of the ultrasonic flowmeter according to the first embodiment except for the configuration of the inlet buffer 30 (specifically, the configurations of the partition plate 33 and the communication portion 35). It has the same configuration as the flow meter 1. Therefore, in the following description, a description of the same configuration as that of the first embodiment will be omitted, and a different configuration will be described in detail.

  That is, similarly to the first embodiment, the ultrasonic flow meter 1 according to the second embodiment is a fuel gas meter that measures the flow rate of the fuel gas, and includes a meter case 5 connected in the middle of the fuel gas pipe 2. The flow rate measuring unit 50 is provided inside. The meter case 5 according to the second embodiment also includes a meter housing 10 having an inlet buffer unit 30, a central space 40, and an outlet buffer unit 45 therein, and a rear cover 20, similarly to the first embodiment. Have been.

(Configuration of Meter Housing in Second Embodiment)
As in the first embodiment, the meter housing 10 according to the second embodiment is made of a metal material such as aluminum or an aluminum alloy. As shown in FIG. 8 to FIG. The space 40 and the outlet buffer 45 are formed in the upper part of the meter housing 10 so as to be arranged in order from the right end to the left end of the meter housing 10.

  Similarly to the first embodiment, the inlet buffer unit 30 according to the second embodiment is partitioned inside the meter case 5 so as to extend in an inverted L-shape along the right side surface and the lower surface of the meter case 5. . The inlet buffer section 30 is a space defined by the partition wall 17A of the meter housing 10, the partition wall 21A of the rear cover 20, and the like inside the meter case 5, as in the first embodiment. It communicates with the inflow port 11 through the inflow chamber 14 and the opening 15. A specific configuration of the entrance buffer unit 30 according to the second embodiment will be described later in detail with reference to FIGS.

  And also in 2nd Embodiment, the central space part 40 is located in the upper part of the meter housing | casing 10 between the inlet buffer part 30 in the left-right direction, and the outlet buffer part 45, and is a substantially box-shaped space. It is partitioned as. Further, similarly to the first embodiment, the outlet buffer section 45 is a space defined in a substantially box shape by the partition wall 17B of the meter housing 10, the partition wall 21B of the rear cover 20, and the like in the upper part of the meter case 5. And is located on the left side inside the meter case 5. The outlet buffer unit 45 communicates with the outside of the meter housing 10 via the outlet 12 (see FIG. 8 and the like).

(Configuration of the entrance buffer unit in the second embodiment)
Next, the configuration of the inlet buffer unit 30 in the ultrasonic flowmeter 1 according to the second embodiment will be described in detail with reference to FIGS. As described above, the inlet buffer unit 30 according to the second embodiment is partitioned inside the meter case 5 so as to extend in an inverted L-shape along the right side surface and the lower surface of the meter case 5, As in the embodiment, the partition plate 33 located inside the entrance buffer unit 30 allows the buffer space 31 located along the right side surface at the upper part of the meter case 5 and the right side at the lower part of the meter case 5. The storage space 32 is extended from the portion toward the left.

  As shown in FIGS. 8 to 10, the partition plate 33 is formed in a plate shape extending rearward from the front wall surface inside the entrance buffer unit 30 and stands upright with respect to the front wall surface. . The partition plate 33 is provided upright at a distance equal to the vertical dimension of the outlet buffer unit 45 at a position separated from the upper surface of the inlet buffer unit 30. The portion located below the partition plate 33 in the inlet buffer portion 30 is referred to as a storage space portion 32.

  Further, the dimension from the front wall surface of the entrance buffer section 30 to the rear edge of the partition plate 33 is formed to be the same as the dimension from the front wall surface of the entrance buffer section 30 to the rear end of the partition wall 17A. Have been. In the second embodiment, a plurality of (for example, seven) grooves 33A are formed on the surface of the rear end edge of the partition plate 33 (see FIGS. 8 to 10). Each groove 33 </ b> A is concavely recessed in the front direction with respect to the surface of the rear edge of the partition plate 33, and extends in the thickness direction of the partition plate 33 (that is, in the vertical direction).

  In the ultrasonic flowmeter 1 according to the second embodiment, when the rear cover 20 is screwed to the meter housing 10, the rear edge of the partition plate 33 comes into airtight contact with the front surface of the rear cover 20. I do. At this time, as shown in FIGS. 9 and 10, the inner surfaces of the plurality of grooves 33A are located at positions separated from the front surface of the rear cover 20 by a predetermined dimension. That is, the buffer space portion 31 and the storage space portion 32 communicate with each other via the communication portion 35 formed by the front surface of the rear cover 20 and the plurality of grooves 33A formed on the rear edge of the partition plate 33. .

  Also in the second embodiment, the buffer space portion 31 is partitioned into a substantially box shape by the partition wall 17A of the meter housing 10, the partition wall 21A of the rear cover 20, and the partition plate 33 in the upper portion of the meter case 5. In addition, it communicates with the inlet 11 through the opening 15, and communicates with the outlet buffer 45 through the measurement flow path 51 of the flow measurement unit 50. Therefore, when the fuel gas flows into the buffer space 31 of the inlet buffer 30 via the opening 15, the fuel gas flows from the inlet 51 </ b> A located in the buffer space 31 to the inside of the measurement flow path 51 through the outlet buffer. 45.

  Also in the second embodiment, the horizontal cross-sectional area of the inlet buffer 30 (that is, the buffer space 31) in the upper part of the meter housing 10 is equal to the horizontal cross-sectional area of the outlet buffer 45. It is configured to be. The partition plate 33 constituting the lower surface of the buffer space portion 31 is provided upright at a distance equal to the vertical dimension of the outlet buffer portion 45 at a distance from the upper surface of the inlet buffer portion 30. Therefore, the buffer space portion 31 according to the second embodiment has a box shape having a volume substantially equal to that of the outlet buffer portion 45.

  The storage space 32 according to the second embodiment is a part of the inlet buffer 30 and is partitioned into a box below the buffer space 31 and the partition plate 33 as in the first embodiment. The water and the like contained in the fuel gas flowing into the inside of the buffer space 31 are stored through the communication section 35. As shown in FIGS. 8 and 9, the storage space 32 according to the second embodiment includes a lower portion of the meter case 5 from below the buffer space 31 to below the central space 40 and the outlet buffer 45. Because of the extension, the lower portion of the meter case 5 is widely used to store a large amount of water and the like contained in the fuel gas.

  The communication portion 35 according to the second embodiment is formed on the front surface of the rear cover 20 and the rear edge of the partition plate 33 when the rear cover 20 is fixed to the rear surface of the meter housing 10 by screwing. The inside of the buffer space 31 and the inside of the storage space 32 communicate with each other such that water and the like contained in the fuel gas can move. Therefore, according to the inlet buffer unit 30, similarly to the first embodiment, the water and the like flowing into the buffer space unit 31 of the inlet buffer unit 30 together with the fuel gas are stored in the storage space unit 32 through the communication unit 35. , And thus water and the like can be stored in the storage space 32.

  The opening area of the communication portion 35 according to the second embodiment (ie, the total value of the opening area of the gap formed by the front surface of the rear cover 20 and the inner surface of each groove portion 33A) is located inside the buffer space portion 31. The opening area of the inlet 51A of the measurement flow path 51 is sufficiently smaller than the opening area. The opening area of the communication portion 35 is, for example, large enough that the flow of the fuel gas generated due to the pulsation of the fuel gas does not reach the storage space portion 32 from the buffer space portion 31 through the communication portion 35.

(Movement of fuel gas and moisture inside the inlet buffer)
Subsequently, in the ultrasonic flowmeter 1 according to the second embodiment, the movement of the fuel gas inside the inlet buffer unit 30 will be described in detail with reference to the drawings. As shown in FIG. 9, when the fuel gas flows from the inflow port 11 to which the pipe 2 is connected, the fuel gas flows through the inflow path 13 and the opening 15 into the inside of the buffer space 31 in the inlet buffer section 30.

  As described above, the inside of the buffer space 31 communicates with the communication section 35 and the inlet 51A of the measurement flow path 51 of the flow rate measurement unit 50 via the communication section 35 and the inlet 51A of the measurement flow path 51. Since the opening area is sufficiently larger than the opening area of the communication part 35, the fuel gas flowing into the buffer space part 31 flows out of the inlet buffer part 30 through the inlet part 51 </ b> A of the measurement flow path part 51. (See FIG. 9).

  Next, in the ultrasonic flowmeter 1 according to the second embodiment, a case where a small amount of fuel gas flows into the buffer space 31 due to pulsation of the fuel gas will be described. As described above, the opening area of the communication section 35 formed by the plurality of grooves 33A is sufficiently smaller than the opening area of the inlet section 51A in the measurement flow path section 51. Therefore, the fuel gas flowing due to the pulsation hardly flows from the buffer space 31 of the inlet buffer 30 to the storage space 32 via the communication portion 35, and the measurement flow passage of the flow measurement unit 50. It flows to the outlet buffer unit 45 via 51. Further, the buffer space portion 31 according to the second embodiment is partitioned into a substantially box shape having a volume substantially equal to that of the outlet buffer portion 45, as in the first embodiment. Therefore, according to the ultrasonic flowmeter 1 according to the second embodiment, the volume difference between the buffer space 31 and the outlet buffer 45 can be reduced, and the pulsation of the fuel gas reduces the measurement accuracy of the ultrasonic flowmeter 1. The effect can be reduced.

  Next, the movement of moisture and the like inside the entrance buffer unit 30 according to the second embodiment will be described in detail with reference to the drawings. Also in the second embodiment, the fuel gas supplied through the pipe 2 and the inlet 11 flows into the inlet buffer 30 through the opening 15 while containing moisture and the like. As shown in FIG. 9, also in the second embodiment, inside the buffer space 31, the inlet 51 </ b> A of the measurement flow path unit 51 in the flow measurement unit 50 is formed on the front wall surface of the inlet buffer 30. It is arranged above the opening 15.

  Accordingly, in the process of flowing from the opening 15 of the buffer space 31 to the inlet 51A of the measurement flow path 51 located above the same, gravity acts on the moisture and the like contained in the fuel gas. Due to the action of the gravity, the moisture and the like contained in the fuel gas are stored in the lower part of the inlet buffer 30 without reaching the inlet 51A of the measurement channel 51, and the plurality of grooves 33A are formed. Flows down in the water movement direction W via the communicating portion 35 constituted by the above, and is stored in the storage space 32 (see FIG. 9).

  As described above, according to the ultrasonic flow meter 1 according to the second embodiment, the water and the like contained in the fuel gas flowing into the buffer space portion 31 of the inlet buffer portion 30 are communicated by the plurality of grooves 33A. Through the section 35, the water can be stored in the storage space 32 in the inlet buffer section 30, so that entry of moisture and the like into the inside of the measurement flow path 51 in the flow rate measurement unit 50 can be suppressed. . According to the ultrasonic flowmeter 1, the storage space 32 in the inlet buffer 30 is located below the central space 40 and the outlet buffer 45 below the buffer space 31 and the partition plate 33. Due to the extension, a large amount of water and the like contained in the fuel gas flowing into the inlet buffer section 30 can be stored inside the storage space section 32.

  As described above, the ultrasonic flowmeter 1 according to the second embodiment connects the inlet buffer unit 30 and the outlet buffer unit 45 inside the meter case 5 to the flow rate measuring unit 50, as in the first embodiment. The fuel gas flowing through the inside of the measurement flow path 51 from the inflow port 11 to the outflow port 12 has a pair of ultrasonic vibrations. By transmitting ultrasonic waves from the transducer 52A and the ultrasonic transducer 52B, the flow rate of the fuel gas can be measured.

  As shown in FIGS. 9 and 10, the inlet buffer unit 30 according to the second embodiment is partitioned into a buffer space 31 and a storage space 32 by a partition plate 33. The partition 33 communicates with the storage space 32 via a communication portion 35 formed by a plurality of grooves 33 </ b> A formed on the rear end edge of the partition 33. Therefore, according to the ultrasonic flowmeter 1, moisture and the like contained in the fuel gas flowing into the buffer space 31 can be stored in the storage space 32 through the communication portion 35, It is possible to suppress entry of moisture and the like into the inside of the measurement flow path 51 (see FIG. 9). Also in the second embodiment, since the storage space 32 extends below the buffer space 31 and the partition plate 33 to below the central space 40 and the outlet buffer 45, the ultrasonic The flow meter 1 can store a large amount of water and the like contained in the fuel gas flowing into the inlet buffer unit 30 in the storage space 32.

  Further, also in the second embodiment, the buffer space portion 31 in the inlet buffer portion 30 is partitioned so as to have substantially the same volume as the outlet buffer portion 45 (see FIGS. 8 and 10), and a plurality of grooves 33A. Is communicated with the storage space portion 32 by the communication portion 35 configured by Thus, according to the ultrasonic flowmeter 1, the fuel gas pulsation suppresses the movement of the fuel gas to the storage space 32 communicated through the communication portion 35 with the pulsation of the fuel gas. The difference in volume of the part 45 can be reduced, and the influence of the pulsation of the fuel gas on the measurement accuracy of the ultrasonic flowmeter 1 can be reduced.

  In the second embodiment, the rear edge of the partition plate 33 is brought into contact with the front surface of the rear cover 20 that forms the inner surface of the entrance buffer unit 30, and is formed on the rear edge of the partition plate 33. The communicating portion 35 is constituted by the plurality of groove portions 33A and the front surface of the rear cover 20 (see FIGS. 9 and 10). Therefore, according to the ultrasonic flowmeter 1, the rear end edge of the partition plate 33 is brought into contact with the front surface of the rear cover 20, so that the communication port 35 is formed and the inlet buffer 30 is connected to the buffer space 31 and the storage space. Section 32. Thereby, the ultrasonic flowmeter 1 appropriately stores the water contained in the fuel gas in the storage space 32 while reducing the influence of the pulsation of the fuel gas on the measurement accuracy of the ultrasonic flowmeter 1. Possible configurations can be realized.

(Third embodiment)
Subsequently, the configuration of the ultrasonic flowmeter 1 according to an embodiment (third embodiment) different from the above-described first embodiment and second embodiment will be described in detail with reference to FIGS. The ultrasonic flowmeter 1 according to the third embodiment has the above-described first and second embodiments except for the configuration of the inlet buffer unit 30 (specifically, the configurations of the partition plate 33 and the communication unit 35). It has the same configuration as the ultrasonic flowmeter 1 according to the embodiment. Therefore, in the following description, the description of the same configuration as the first embodiment and the second embodiment will be omitted, and the different configuration will be described in detail.

  That is, the ultrasonic flow meter 1 according to the second embodiment is a fuel gas meter that measures the flow rate of the fuel gas, similarly to the first and second embodiments, and is connected in the middle of the fuel gas pipe 2. The flow rate measuring unit 50 is disposed inside the meter case 5. The meter case 5 according to the third embodiment also includes a meter housing 10 having an inlet buffer 30, a central space 40, and an outlet buffer 45 therein, and a rear cover 20.

(Configuration of Meter Housing in Third Embodiment)
The meter housing 10 according to the third embodiment is made of a metal material such as aluminum or an aluminum alloy as in the first embodiment and the second embodiment. As shown in FIG. The central space 40 and the outlet buffer 45 are formed in the upper part of the meter housing 10 so as to be arranged in order from the right end to the left end of the meter housing 10.

  The inlet buffer unit 30 according to the third embodiment extends in an inverted L-shape along the right side surface and the lower surface of the meter case 5 inside the meter case 5 as in the first and second embodiments. Is divided into The inlet buffer section 30 is a space defined by the partition wall 17A of the meter housing 10, the partition wall 21A of the rear cover 20, and the like inside the meter case 5, as in the first and second embodiments. , The inflow path 13, the inflow chamber 14, and the opening portion 15, and communicates with the inflow port 11.

  As shown in FIG. 11, in the entrance buffer unit 30 according to the third embodiment, a partition fixing part 36 is formed at a predetermined position on the front wall surface part. The partition fixing part 36 is different from the first and second embodiments in that a partition plate 33 (see FIG. 12) formed separately from the meter housing 10 is placed at a predetermined position inside the entrance buffer part 30. Used when fixing. The position where the partition fixing portion 36 is formed is below the position where the opening portion 15 is formed on the front wall surface portion, and a distance substantially equal to the vertical dimension of the outlet buffer portion 45 is set from the upper surface of the inlet buffer portion 30. It is a position separated. A specific configuration of the entrance buffer unit 30 according to the third embodiment will be described later in detail with reference to FIGS.

  The central space 40 according to the third embodiment is located between the inlet buffer unit 30 and the outlet buffer unit 45 in the left-right direction in the upper part of the meter housing 10 and has a substantially box-shaped space. It is partitioned. Further, similarly to the first and second embodiments, the outlet buffer portion 45 has a substantially box-like shape by the partition wall 17B of the meter housing 10, the partition wall 21B of the rear cover 20, and the like in the upper part of the meter case 5. And is located on the left side inside the meter case 5. The outlet buffer unit 45 communicates with the outside of the meter housing 10 via the outlet 12 (see FIG. 11).

(Configuration of the partition plate in the third embodiment)
Subsequently, the configuration of the partition plate 33 according to the third embodiment will be described in detail with reference to FIG. As described above, the partition plate 33 according to the third embodiment is attached to a predetermined position inside the entrance buffer unit 30 by the partition fixing unit 36 formed on the front wall surface of the entrance buffer unit 30, and the third embodiment is performed. The inlet buffer section 30 according to the embodiment is partitioned into a buffer space section 31 and a storage space section 32 (see FIGS. 13 and 14).

  As shown in FIGS. 12 to 14, the partition plate 33 is formed by bending a metal plate material formed in a rectangular plate shape at a substantially right angle, and extends along the front wall surface of the entrance buffer unit 30. And a plate-like portion having substantially the same shape as the horizontal cross section of the entrance buffer unit 30. A plurality of through holes 33B penetrating in the plate thickness direction of the partition plate 33 are formed in the plate portion of the partition plate 33 in the third embodiment. On the other hand, in the partition plate 33, a mounting hole 33 </ b> C is formed at a position corresponding to the partition fixing portion 36 in the entrance buffer unit 30 at a portion extending along the front wall surface of the entrance buffer unit 30.

  In the third embodiment, the partition plate 33 is fixed at a predetermined position inside the entrance buffer unit 30 by cooperating the mounting hole 33C and the partition fixing unit 36 formed in the entrance buffer unit 30. The part 30 can be partitioned into a buffer space part 31 and a storage space part 32. The position where the partition fixing portion 36 is formed is below the position where the opening portion 15 is formed on the front wall surface portion, and a distance substantially equal to the vertical dimension of the outlet buffer portion 45 is set from the upper surface of the inlet buffer portion 30. Since the positions are separated from each other, the buffer space 31 in the third embodiment has substantially the same volume as the outlet buffer 45.

(Configuration of the entrance buffer unit in the third embodiment)
Here, the configuration of the inlet buffer unit 30 in the ultrasonic flowmeter 1 according to the third embodiment will be described in detail with reference to FIGS. The inlet buffer unit 30 according to the third embodiment is partitioned inside the meter case 5 so as to extend in an inverted L-shape along the right side surface and the lower surface of the meter case 5. A partition plate 33 attached via a partition fixing portion 36 to the buffer space portion 31 located along the right side surface at the upper portion of the meter case 5 and the right side portion to the left side at the lower portion of the meter case 5. And a storage space 32 extending therefrom.

  As shown in FIGS. 13 and 14, the partition plate 33 is configured to horizontally close the inside of the entrance buffer unit 30 with a plate-like portion extending rearward from the front wall surface inside the entrance buffer unit 30. It is attached. Since the partition plate 33 is attached at a distance equal to the vertical dimension of the outlet buffer unit 45 at a position separated from the upper surface of the inlet buffer unit 30, a buffer space having a volume substantially equal to that of the outlet buffer unit 45 is provided. It is divided into a part 31 and a storage space part 32 located below the part 31. As shown in FIG. 14 and the like, since a plurality of through holes 33B are formed in the partition plate 33, the buffer space 31 in the third embodiment is a communication portion formed by the through holes 33B of the partition plate 33. Through 35, it communicates with the lower storage space 32.

  Also in the third embodiment, the buffer space portion 31 is partitioned into a substantially box shape by the partition wall 17A of the meter housing 10, the partition wall 21A of the rear cover 20, and the partition plate 33 in the upper part of the meter case 5. In addition, it communicates with the inlet 11 through the opening 15, and communicates with the outlet buffer 45 through the measurement flow path 51 of the flow measurement unit 50. Therefore, when the fuel gas flows into the buffer space 31 of the inlet buffer 30 via the opening 15, the fuel gas flows from the inlet 51 </ b> A located in the buffer space 31 to the inside of the measurement flow path 51 through the outlet buffer. 45.

  Also in the third embodiment, the horizontal cross-sectional area of the inlet buffer section 30 (that is, the buffer space section 31) in the upper portion of the meter housing 10 is equal to the horizontal cross-sectional area of the outlet buffer section 45. It is configured to be. The partition plate 33 constituting the lower surface of the buffer space portion 31 is attached with a partition fixing portion 36 at a distance equal to the vertical dimension of the outlet buffer portion 45 at a position separated from the upper surface of the inlet buffer portion 30. Accordingly, the buffer space portion 31 according to the third embodiment has a box shape having a volume substantially equal to that of the outlet buffer portion 45.

  The storage space 32 according to the third embodiment is a part of the inlet buffer 30 as in the first and second embodiments, and has a box-like shape below the buffer space 31 and the partition plate 33. , And stores moisture and the like contained in the fuel gas flowing into the buffer space portion 31 through the communication portion 35. As shown in FIGS. 11 and 13, the storage space 32 according to the third embodiment includes a lower portion of the meter case 5 from below the buffer space 31 to below the central space 40 and the outlet buffer 45. Because of the extension, the lower portion of the meter case 5 is widely used to store a large amount of water and the like contained in the fuel gas.

  As shown in FIGS. 13 and 14, the communication part 35 according to the third embodiment is constituted by a plurality of through holes 33 </ b> B formed in the partition plate 33, and the inside of the buffer space part 31 and the storage space part 32 are formed. Are communicated so that moisture and the like contained in the fuel gas can move. Therefore, according to the inlet buffer unit 30, similarly to the first and second embodiments, together with the fuel gas, the water and the like flowing into the buffer space 31 of the inlet buffer unit 30 via the communication unit 35. Therefore, the water can flow into the storage space 32, and thus water and the like can be stored in the storage space 32.

  The opening area of the communication section 35 according to the third embodiment (that is, the total value of the opening areas of the plurality of through holes 33 </ b> B in the partition plate 33) is the measurement flow path section 51 located inside the buffer space section 31. Is formed sufficiently smaller than the opening area of the entrance portion 51A. The opening area of the communication portion 35 is, for example, large enough that the flow of the fuel gas generated due to the pulsation of the fuel gas does not reach the storage space portion 32 from the buffer space portion 31 through the communication portion 35.

(Movement of fuel gas and moisture inside the inlet buffer)
Subsequently, in the ultrasonic flowmeter 1 according to the third embodiment, the movement of the fuel gas inside the inlet buffer unit 30 will be described in detail with reference to the drawings. As shown in FIG. 13, when the fuel gas flows from the inflow port 11 to which the pipe 2 is connected, the fuel gas flows through the inflow path 13 and the opening 15 into the inside of the buffer space 31 in the inlet buffer 30.

  As described above, the inside of the buffer space 31 communicates with the communication section 35 and the inlet 51A of the measurement flow path 51 of the flow rate measurement unit 50 via the communication section 35 and the inlet 51A of the measurement flow path 51. Since the opening area is sufficiently larger than the opening area of the communication part 35, the fuel gas flowing into the buffer space part 31 flows out of the inlet buffer part 30 through the inlet part 51 </ b> A of the measurement flow path part 51. (See FIG. 13).

  Subsequently, a case will be described in which the fuel gas slightly flows into the buffer space 31 with the pulsation of the fuel gas in the ultrasonic flowmeter 1 according to the third embodiment. As described above, the opening area of the communication section 35 formed by the plurality of through holes 33B is sufficiently smaller than the opening area of the entrance section 51A in the measurement flow path section 51. Therefore, the fuel gas flowing due to the pulsation hardly flows from the buffer space 31 of the inlet buffer 30 to the storage space 32 via the communication portion 35, and the measurement flow passage of the flow measurement unit 50. It flows to the outlet buffer unit 45 via 51. Also, in the third embodiment, the buffer space 31 is partitioned into a substantially box shape having a volume substantially equal to that of the outlet buffer 45, as in the first and second embodiments. Therefore, according to the ultrasonic flowmeter 1, the volume difference between the buffer space 31 and the outlet buffer 45 can be reduced, and the influence of the pulsation of the fuel gas on the measurement accuracy of the ultrasonic flowmeter 1 is reduced. be able to.

  Next, the movement of moisture and the like inside the entrance buffer unit 30 according to the third embodiment will be described in detail with reference to the drawings. Also in the third embodiment, the fuel gas supplied through the pipe 2 and the inlet 11 flows into the inlet buffer 30 through the opening 15 while containing moisture and the like. As shown in FIG. 13, inside the buffer space 31, the inlet 51 </ b> A of the measurement flow path unit 51 in the flow rate measuring unit 50 is higher than the opening 15 formed on the front wall surface of the inlet buffer 30. It is arranged so that it becomes.

  Accordingly, in the process of flowing from the opening 15 of the buffer space 31 to the inlet 51A of the measurement flow path 51 located above the same, gravity acts on the moisture and the like contained in the fuel gas. Due to the action of the gravity, the moisture and the like contained in the fuel gas are stored in the lower part of the inlet buffer 30 without reaching the inlet 51A of the measurement channel 51, and the plurality of grooves 33A are formed. Flows down in the water movement direction W via the communicating portion 35 constituted by the above, and is stored in the storage space 32 (see FIG. 13).

  As described above, according to the ultrasonic flowmeter 1 according to the third embodiment, the moisture and the like contained in the fuel gas flowing into the buffer space portion 31 of the inlet buffer portion 30 are constituted by the plurality of through holes 33B. It can be stored in the storage space part 32 in the inlet buffer part 30 through the communication part 35, and therefore, it is possible to suppress the entry of moisture and the like into the measurement flow path part 51 in the flow rate measurement unit 50. it can. According to the ultrasonic flowmeter 1, the storage space 32 in the inlet buffer 30 is located below the central space 40 and the outlet buffer 45 below the buffer space 31 and the partition plate 33. Due to the extension, a large amount of water and the like contained in the fuel gas flowing into the inlet buffer section 30 can be stored inside the storage space section 32.

  As described above, the ultrasonic flowmeter 1 according to the third embodiment includes the inlet buffer unit 30 and the outlet buffer unit 45 inside the meter case 5 as in the first embodiment and the second embodiment. It has so that it may be connected by the measurement channel part 51 of the flow rate measurement unit 50, and the fuel gas which flows through the inside of the measurement channel part 51 from the inflow port 11 toward the outflow port 12 may be By transmitting ultrasonic waves from the pair of ultrasonic transducers 52A and 52B, the flow rate of the fuel gas can be measured.

  As shown in FIGS. 13 and 14, the inlet buffer 30 according to the third embodiment is partitioned into a buffer space 31 and a storage space 32 by a partition plate 33 attached via a partition fixing portion 36. The buffer space portion 31 communicates with the storage space portion 32 via a communication portion 35 formed by a plurality of through holes 33B formed in the partition plate 33. Therefore, according to the ultrasonic flowmeter 1, moisture and the like contained in the fuel gas flowing into the buffer space 31 can be stored in the storage space 32 via the communication portion 35, It is possible to suppress entry of moisture and the like into the inside of the measurement flow path 51 (see FIG. 13). Also in the third embodiment, the storage space 32 extends below the buffer space 31 and the partition plate 33 to below the central space 40 and the outlet buffer 45, and therefore, The flow meter 1 can store a large amount of water and the like contained in the fuel gas flowing into the inlet buffer section 30 in the storage space section 32.

  Furthermore, also in the third embodiment, the buffer space 31 in the inlet buffer 30 is partitioned so as to have a volume substantially equal to the outlet buffer 45 (see FIGS. 11 and 13), and a plurality of through holes. The communication space 35 configured by 33 </ b> B communicates with the storage space 32. Thus, according to the ultrasonic flowmeter 1, the fuel gas pulsation suppresses the movement of the fuel gas to the storage space 32 communicated through the communication portion 35 with the pulsation of the fuel gas. The difference in volume of the part 45 can be reduced, and the influence of the pulsation of the fuel gas on the measurement accuracy of the ultrasonic flowmeter 1 can be reduced.

  Further, the partition plate 33 according to the third embodiment is different from the first and second embodiments, and is formed separately from the meter housing 10, and the inlet buffer communicating with the inlet 11. The part 30 (that is, the buffer space part 31) is attached to the inside of the inlet buffer part 30 via the partition fixing part 36 so that the capacity of the part is substantially equal to that of the outlet buffer part 45. That is, according to the ultrasonic flow meter 1, for example, as shown in FIG. 11, the ultrasonic flow meter 1 is formed separately from the meter housing 10 having the inlet buffer unit 30, the central space 40, and the outlet buffer unit 45. By disposing the partition plate 33 (see FIG. 12), the inlet buffer unit 30 can be partitioned into a buffer space 31 and a storage space 32. That is, the ultrasonic flowmeter 1 uses the partition plate 33 formed separately to reduce the influence of the pulsation of the fuel gas on the measurement accuracy of the ultrasonic flowmeter 1 while reducing the moisture contained in the fuel gas. Can be appropriately stored in the storage space 32.

  The communication portion 35 according to the third embodiment is constituted by a plurality of through holes 33B penetrating the partition plate 33 in the plate thickness direction. As shown in FIG. 12, when the partition plate 33 is formed separately, when the partition plate 33 is formed integrally with the meter housing 10 as in the first and second embodiments. As compared with (see FIGS. 2 and 8), the degree of freedom regarding the formation of the through-hole 33B (for example, the degree of freedom regarding the position, size, shape, and the like of the through-hole 33B) is increased. Therefore, according to the ultrasonic flowmeter 1, the buffer space 31 and the storage space 32 can be communicated with each other by the communication portion 35 including the desired through-hole 33 </ b> B, so that the pulsation of the fuel gas is reduced. It is possible to realize a configuration in which the moisture contained in the fuel gas can be appropriately stored in the storage space 32 while reducing the influence on the measurement accuracy of the ultrasonic flowmeter 1.

  In the embodiment described above, the ultrasonic flowmeter 1 is an example of the ultrasonic flowmeter of the present invention, and the meter case 5, the meter housing 10, and the rear cover 20 are examples of the meter case of the present invention. The inflow port 11 is an example of the inflow port in the present invention, and the outflow port 12 is an example of the outflow port in the present invention. The flow measurement unit 50 is an example of a flow measurement unit in the present invention, and the measurement flow path unit 51 is an example of a measurement flow path unit in the present invention. The ultrasonic transducer 52A and the ultrasonic transducer 52B are an example of a pair of ultrasonic transducers in the present invention, and the entrance buffer unit 30 is an example of an entrance buffer unit in the present invention. The outlet buffer section 45 is an example of an outlet buffer section in the present invention, and the central space section 40 is an example of a central space section in the present invention. The buffer space 31 is an example of the buffer space in the present invention, and the storage space 32 is an example of the storage space in the present invention. And the partition plate 33 is an example of the partition plate in the present invention, and the communicating portion 35 is an example of the communicating portion in the present invention. The groove 33A is an example of the groove in the present invention, and the through hole 33B is an example of the through hole in the present invention.

  As described above, the present invention has been described based on the embodiments. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, the configuration of the communication section 35 in the above-described embodiment is merely an example, and any configuration that allows the buffer space section 31 and the storage space section 32 of the inlet buffer section 30 to communicate with each other can be configured, in size, shape, and the like. Can be changed as appropriate.

DESCRIPTION OF SYMBOLS 1 Ultrasonic flow meter 5 Meter case 10 Meter housing 11 Inflow port 12 Outflow port 20 Rear cover 30 Inlet buffer section 31 Buffer space section 32 Storage space section 33 Partition plate 33A Groove section 33B Through hole 35 Communication section 40 Central space section 45 Exit buffer 50 Flow rate measurement unit 51 Measurement flow channel 52A Ultrasonic transducer 52B Ultrasonic transducer

Claims (4)

A meter case having an inlet for the fluid to be measured and an outlet for the fluid to be measured,
A flow rate measurement unit disposed inside the meter case and measuring a flow rate of the fluid to be measured passing through the inside of the meter case through the inflow port and the outflow port,
The flow rate measurement unit,
A measurement channel portion through which the fluid to be measured flows from the inflow port to the outflow port,
A pair of ultrasonic transducers respectively disposed on the upstream side and the downstream side of the flow of the fluid to be measured in the measurement flow path portion,
The meter case is
An inlet buffer unit that communicates with the inlet, and is partitioned so that the fluid to be measured flowing through the inlet flows into the inlet of the measurement channel unit.
Communicates with the said outlet, so that the fluid to be measured that flows out from the outlet portion of the measurement flow path portion flows out to the outside of the meter case through the outlet, with a smaller volume than the inlet buffer A partitioned exit buffer,
A central space formed between the inlet buffer and the outlet buffer, and penetrated by the measurement flow path;
The entrance buffer unit includes:
A partition plate that partitions a portion of the inlet buffer portion communicating with the inlet portion and the inflow port of the measurement channel portion so as to have a volume substantially equal to the outlet buffer portion,
A buffer that is a part of the inlet buffer section defined by the partition plate and is partitioned such that the fluid to be measured flowing through the inflow port flows into an inlet section of the measurement channel section. Space part,
Below the partition plate and the buffer space, a storage space that extends toward the central space and stores moisture contained in the fluid to be measured that has flowed into the inlet buffer.
The constructed using the partition plate, wherein the buffer space portion and between said reservoir space, have a, a communicating portion moisture of the buffer space portion communicates movably,
The meter case is an end of an inflow passage extending from the inflow port, and has an opening in the inner wall communicating with the buffer space,
The inlet of the measurement flow path is located above the opening in the buffer space,
The partition plate extends from the inner wall portion toward the inside of the entrance buffer portion in the entrance buffer portion,
The ultrasonic flowmeter according to claim 1, wherein the communication portion is located inside the inlet buffer portion on a side opposite to the inner wall portion in a direction in which the partition plate extends . Of the inner wall portions defining the inlet buffer portion, the one in which the opening is formed is defined as a first inner wall portion, and the one on the opposite side to the first inner wall portion in the direction in which the partition plate extends is defined as a second inner wall. Department
The communication section is
The ultrasonic flowmeter according to claim 1, wherein the ultrasonic flowmeter is constituted by the second inner wall portion and an edge of the partition plate separated by a predetermined distance from the second inner wall portion . Of the inner wall portions defining the inlet buffer portion, the one in which the opening is formed is defined as a first inner wall portion, and the one on the opposite side to the first inner wall portion in the direction in which the partition plate extends is defined as a second inner wall. Department
The partition plate,
An edge of the partition plate that contacts the second inner wall portion has a groove that extends in the thickness direction of the partition plate and that is concavely concave,
The communication section is
Ultrasonic flowmeter according to claim 1, characterized in that it is configured with the second inner wall portion, by said groove. The ultrasonic flowmeter according to any one of claims 1 to 3, wherein the inflow passage extends downward from the inflow port.

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