JP2021117215A - Ultrasonic flowmeter - Google Patents

Abstract

To provide an ultrasonic flowmeter with which component counts and assembly man-hours are few.SOLUTION: The ultrasonic flowmeter is provided with an inlet passage part 14 separated from an inlet buffer part 16 by a first partition wall 25 projecting to the inward face of a case 10, with a gas having flowed in from an inflow port 13 flowing down to the downstream side, and a middle hollow part 10c accommodating a measurement unit 50 and arranged between the inlet buffer part 16 and an outlet buffer part 17. A gas having flowed in from the inflow port 13 and flowed down to the downstream side of the inlet passage part 14 flows in to the inlet buffer part 16 via an inlet communication hole 25a provided in the first partition wall 25.SELECTED DRAWING: Figure 3

Description

The present invention relates to an ultrasonic flow meter.

In general, periodic and regular pressure fluctuations are likely to occur in the gas piping due to the usage conditions of gas appliances such as gas heat pump air conditioners or pressure fluctuations on the gas supply side, and the flow velocity in the forward and reverse flow directions. Change is likely to occur. The ultrasonic flow meter calculates the flow rate volume to pass based on the instantaneous flow velocity measured at a constant cycle. For this reason, if the above-mentioned change in flow velocity becomes large when the gas is not used or used in a low flow rate range, the error in the amount of gas used becomes large due to the variation in the measured flow rate, which is unfair to the charged gas charge. An ultrasonic flow meter with a small variation in the measured flow rate is required because it may produce results.
Conventionally, as an ultrasonic flow meter, for example, a gas flowing in from an inflow port 12 passes through a passage hole 36b of a rectifying plate 36 through a shutoff valve 34, flows into a measuring tube 40, and then passes through the rectifying plate. There is an ultrasonic flowmeter that flows out from the outlet 14 through the passage hole 38b of 38 (see Patent Document 1).

Japanese Unexamined Patent Publication No. 2009-186429

However, in the ultrasonic flowmeter, the straightening vane 36 provided with the passage hole 36b for obtaining the orifice effect and the straightening vane 38 provided with the passage hole 38b are separate from the gas meter 10, and the number of parts and the number of assembly steps are increased. There is a problem that there are many.
In view of the above problems, it is an object of the present invention to provide an ultrasonic flowmeter having a small number of parts and assembling man-hours.

The ultrasonic flowmeter according to the present invention solves the above-mentioned problems.
With the case
The inlet buffer, which is a space partitioned on the upstream side of the case,
The outlet buffer portion, which is a partitioned space on the downstream side in the case,
It has a measuring unit that is housed in the case, has an inlet portion that communicates with the inlet buffer portion, and an outlet portion that communicates with the outlet buffer portion.
The gas flowing in from the inflow port communicating with the inflow portion of the case flows in from the inlet portion of the measuring unit communicating with the inlet buffer portion, circulates in the flow passage in the measuring unit, and communicates with the outlet portion. An ultrasonic flowmeter that measures the flow rate of gas passing through the measuring unit by flowing out of the outflow section through the outlet buffer section.
An inlet flow path portion that is partitioned from the inlet buffer portion by a partition wall projecting from the inward surface of the case and in which the gas flowing in from the inflow port flows down to the downstream side.
A central space portion arranged between the inlet buffer portion and the outlet buffer portion and accommodating the measurement unit is provided.
The gas that has flowed in from the inflow port and has flowed down to the downstream side of the inlet flow path portion flows into the inlet buffer portion through the inlet communication hole provided in the partition wall.

According to the present invention, since a partition wall having an inlet communication hole is projected on the inward surface of the case, an ultrasonic flowmeter with a small number of parts and assembling man-hours can be obtained.

In the embodiment of the present invention, the inlet communication hole may be arranged inside the inlet portion of the measuring unit.
According to this embodiment, the creepage distance through which the gas flows becomes long, and the pulsation of the gas can be reduced, so that an ultrasonic flowmeter with a small variation in the measured flow rate can be obtained.

In another embodiment of the present invention, the inlet buffer partition wall that partitions the inlet buffer portion and the central space portion may be provided with a notch portion that allows the liquid that has flowed into the inlet buffer portion to flow out to the central space portion. good.
According to this embodiment, even if a large amount of liquid invades the inlet buffer portion together with the gas, the liquid can be stored on the bottom surface of the central space portion as well. Therefore, it is possible to prevent the liquid from entering the measuring unit and prevent the measurement flow rate from increasing in variation.

In a different embodiment of the present invention, a partition wall provided with an outlet communication hole may be provided on the inward surface of the case between the outlet buffer portion and the outflow portion of the case.
According to this embodiment, an ultrasonic flowmeter with a small number of parts and assembling man-hours can be obtained.

In another embodiment of the present invention, the outlet buffer portion may directly communicate with the outflow portion of the case.
According to this embodiment, so-called gas release is improved and pressure loss can be reduced.

In a different embodiment of the present invention, the outlet buffer portion may be formed so that the cross-sectional area increases toward the downstream side.
According to this embodiment, so-called gas release is further improved, and pressure loss can be further reduced.

In another embodiment of the present invention, at least one of the opening edge of the inlet and the opening edge of the outlet of the cylinder of the measuring unit is flush with the outward surface of the buffer. May be placed in.
According to the present embodiment, the outward surface of the buffer portion and the opening edge portion of the inlet portion and / or the opening portion of the measuring unit are flush with each other, so that the inflow and outflow of gas are smooth. , Pressure loss is reduced and variation in measured flow rate is reduced.

In a different embodiment of the present invention, a shielding plate located between the inflow port and the inlet communication hole may be provided on the inward surface of the case.
According to this embodiment, the gas flowing in from the inflow port collides with the shielding plate and detours, so that the creepage distance becomes long, the pulsation of the gas is absorbed and relaxed, and the variation in the measured flow rate can be reduced.

As another embodiment of the present invention, the central space portion formed between the inlet buffer portion and the outlet buffer portion and the inlet flow path portion may be communicated with each other.
According to this embodiment, the gas staying in the central space serves as a cushioning material, and by absorbing and relaxing the pulsation of the inflowing gas, the variation in the measured flow rate can be reduced.

As a new embodiment of the present invention, a bulging portion that forms the front and back surfaces of the case and bulges outward on at least one of the side walls facing each other with the central space portion in between. It may be provided.
According to this embodiment, there is an effect that the amount of water stored in the invading fluid is increased by increasing the volume of the central space portion.

It is an overall perspective view of the ultrasonic flowmeter which concerns on 1st Embodiment. It is the whole perspective view which looked at the ultrasonic flowmeter shown in FIG. 1 from a different angle. It is a perspective view which shows the state which removed the cover body from the ultrasonic flowmeter shown in FIG. It is a perspective view which looked at the lid body shown in FIG. 1 from the back side. It is a perspective view of the case body shown in FIG. It is a vertical cross-sectional perspective view of the ultrasonic flowmeter shown in FIG. It is a cross-sectional view of the ultrasonic flowmeter shown in FIG. It is another cross-sectional view of the ultrasonic flowmeter shown in FIG. It is a vertical cross-sectional perspective view of the measuring unit shown in FIG. It is a right side vertical cross-sectional view of the measuring unit shown in FIG. It is a partial cross-sectional view of the measuring unit shown in FIG. It is a perspective view which shows the state which removed the cover body from the ultrasonic flowmeter which concerns on 2nd Embodiment. It is a perspective view which looked at the lid body of the ultrasonic flowmeter which concerns on 2nd Embodiment from the back side. It is a perspective view of the case body shown in FIG. It is a vertical cross-sectional perspective view of the ultrasonic flowmeter which concerns on 2nd Embodiment. It is a perspective view which shows the state which removed the cover body from the ultrasonic flowmeter which concerns on 3rd Embodiment. It is a perspective view of the case body shown in FIG. It is an overall perspective view of the ultrasonic flowmeter which concerns on 4th Embodiment. FIG. 8 is an overall perspective view of the ultrasonic flowmeter shown in FIG. 18 viewed from different angles. It is a perspective view which shows the state which removed the cover body from the ultrasonic flowmeter shown in FIG. It is a perspective view of the case body shown in FIG. It is a vertical cross-sectional view of the ultrasonic flowmeter shown in FIG. It is a cross-sectional view of the ultrasonic flowmeter shown in FIG. It is an overall perspective view of the ultrasonic flowmeter which concerns on 5th Embodiment. It is the whole perspective view which looked at the ultrasonic flowmeter shown in FIG. 24 from a different angle. FIG. 3 is an overall perspective view showing a state in which the lid is removed from the ultrasonic flowmeter shown in FIG. 24. It is a perspective view which looked at the lid body shown in FIG. 24 from the back side. FIG. 6 is an overall perspective view showing a state in which the gasket is removed from the ultrasonic flow meter shown in FIG. 26. It is a perspective view of the case body shown in FIG. 24. It is a vertical cross-sectional view of the ultrasonic flowmeter shown in FIG. 24. It is a central vertical sectional view of the ultrasonic flowmeter shown in FIG. 24. It is a front vertical sectional view of the ultrasonic flowmeter shown in FIG. 24. It is a bar graph figure which shows the result of Example 1 which calculated the flow rate of the ultrasonic flow meter which concerns on 1st Embodiment. It is a graph which shows the result of Example 1 which calculated the pressure loss of the ultrasonic flowmeter which concerns on 1st Embodiment. It is a bar graph diagram which shows the result of Example 2 which calculated the flow rate of the ultrasonic flow meter which concerns on 2nd Embodiment. It is a bar graph diagram which shows the result of Example 3 which calculated the flow rate of the ultrasonic flow meter which concerns on 3rd Embodiment. It is a graph which shows the result of Examples 2 and 3 which calculated the pressure loss of the ultrasonic flowmeter which concerns on 2nd and 3rd Embodiment, respectively. It is a bar graph diagram which shows the result of Example 4 which calculated the flow rate of the ultrasonic flow meter which concerns on 4th Embodiment. It is a graph which shows the result of Example 4 which calculated the pressure loss of the ultrasonic flowmeter which concerns on 4th Embodiment. It is a bar graph diagram which shows the result of Example 5 which calculated the flow rate of the ultrasonic flow meter which concerns on 5th Embodiment. It is a graph which shows the result of Example 5 which calculated the pressure loss of the ultrasonic flowmeter which concerns on 5th Embodiment. It is a bar graph figure which shows the result of having calculated the flow rate of the ultrasonic flowmeter which concerns on a comparative example. It is a graph which shows the result of Examples 6 and 7 which measured the pressure fluctuation different with respect to the frequency of 1st Embodiment and 4th Embodiment respectively. It is a graph which shows the result of Example 8 which measured the pressure fluctuation different with respect to the frequency of 5th Embodiment. It is a flow trace diagram of Example 9 which visualized the flow of the gas which concerns on 1st Embodiment. It is a trace diagram of Example 10 which visualized the flow of the gas which concerns on 3rd Embodiment.

The ultrasonic flowmeter of the first embodiment according to the present invention will be described with reference to the accompanying drawings shown in FIGS. 1 to 11.
The ultrasonic flowmeter according to the first embodiment is roughly composed of a case 10, a shutoff valve 40, and a measuring unit 50.

The case 10 is made of a metal material such as aluminum or an aluminum alloy, has a box shape as shown in FIGS. 1 and 2, and has an inflow portion 11 arranged on one end side of the upper surface thereof and the other end side. The outflow portion 12 is arranged in.
Further, the case 10 is composed of a case main body 20 and a lid body 30. Then, at the inflow port 13 (see FIG. 6) located at the lower end of the inflow portion 11, a shutoff valve 40 provided with a valve body 41 is provided in order to prevent gas from flowing into the internal space of the case 10 at the time of abnormality. It is arranged.

As shown in FIG. 5, the internal space of the case body 20 includes an outlet flow path partition wall 21 and an outlet buffer partition wall 22 projecting so as to be continuous vertically, and an inlet projecting vertically so as to be continuous. The flow path partition wall 23 and the inlet buffer partition wall 24 are divided into three spaces on the left and right. In particular, the entrance side space portion 10a is arranged on the right side of the case main body 20, the exit side space portion 10b is arranged on the left side of the case main body 20, and the central space portion 10c is arranged in the center of the case main body 20.

The entrance side space portion 10a is divided into upper and lower two stages by an inlet flow path portion 14 and an inlet buffer portion 16 by integrally projecting a horizontally extending first partition wall 25 into the case body 20. There is. An inlet communication hole 25a is formed in the first partition wall 25. By providing the inlet communication hole 25a, a substantially orifice structure is formed, and an ultrasonic flowmeter capable of preventing erroneous measurement of the measuring unit due to pressure fluctuation can be obtained. Further, the inlet communication hole 25a is arranged inside the inlet portion 52a of the measurement unit 50, which will be described later, and the creepage distance is longer.

Further, as shown in FIG. 5, the inlet buffer partition wall 24 is provided with an engaging receiving portion 24a for supporting the measurement unit 50 described later. Further, the inlet buffer partition wall 24 is provided with a notch portion 24b for guiding the liquid that has flowed in at the same time as the gas from the inlet buffer portion 16 to the central space portion 10c (FIG. 6). Therefore, even if a large amount of liquid flows into the inlet side space portion 10a, it is possible to prevent the liquid from entering the measuring unit 50 by storing the liquid on the bottom surfaces of the inlet buffer portion 16 and the central space portion 10c.

As shown in FIG. 3, the outlet side space portion 10b is provided with the outlet buffer portion 17 and the outlet flow path portion 18 by integrally projecting the second partition wall 26 extending in the horizontal direction into the case body 20. It is divided into two upper and lower tiers. The second partition wall 26 is provided with an outlet communication hole 26a for allowing gas to flow out. By providing the outlet communication hole 26a, a substantially orifice structure is formed, and an ultrasonic flowmeter capable of preventing erroneous measurement of the measuring unit due to pressure fluctuation can be obtained.
Further, the outlet communication hole 26a is arranged inside the outlet portion 52b of the measurement unit 50, which will be described later, and the creepage distance is long.

As shown in FIG. 5, a third partition wall 27 is horizontally projected from the central space portion 10c so as to bridge the outlet buffer partition wall 22 and the inlet buffer partition wall 24, and the cutout portion 24b is provided. A water reservoir space portion 10d communicating with the inlet buffer portion 16 is formed. Further, the outlet buffer partition wall 22 is provided with an engagement receiving portion 22a to support the measurement unit 50 described later.

As shown in FIG. 4, the lid 30 has a front shape capable of covering the opening of the case body 20. Then, on the inward surface of the lid 30, the outlet flow path partition wall 21, the outlet buffer partition wall 22, the inlet flow path partition wall 23, the inlet buffer partition wall 24, the first partition wall 25, and the second partition are provided. At positions abutting against the wall 26 and the third partition wall 27, the outlet flow path partition wall 31 and the outlet buffer partition wall 32, the inlet flow path partition wall 33 and the inlet buffer partition wall 34, the first partition wall 35, and the like. The second partition wall 36 and the third partition wall 37 are provided so as to project from each other. Further, an inlet communication hole 35a is formed in the first partition wall 35. Further, an outlet communication hole 36a is formed in the second partition wall 36.

As shown in FIG. 9, the measuring unit 50 includes a tubular body 51 having a substantially rectangular cross section having an inlet portion 52a and an outlet portion 52b at both ends, and a measuring circuit unit 53 arranged at the center of the upper surface of the tubular body 51. It is composed of.

As shown in FIGS. 10 and 11, the tubular body 51 has five straightening vanes 56a, 56b, 56c, 56d, and 56e arranged side by side at a uniform pitch in the central portion of the flow path in the tubular body 51. , 6 layers of measurement flow paths 57a, 57b, 57c, 57d, 57e, 57f are formed. Further, in order to prevent the O-ring 59 from coming off, the tubular body 51 is formed with two sets of a pair of annular ribs 58a and 58b on the outer surface thereof (FIG. 9). Further, a reinforcing rib 58c is provided so as to project from the outer surface of the tubular body 51 (see FIG. 3).

As shown in FIG. 9, the measurement circuit unit 53 includes a pair of ultrasonic vibrators 54a and 54b arranged in a substantially V shape and a control circuit board arranged above the ultrasonic vibrators 54a and 54b. It is composed of 55 and.
Then, the ultrasonic waves emitted from one ultrasonic vibrator 54a pass through the measurement flow paths 57a to 57f formed between the rectifying plates 56a, 56b, 56c, 56d, 56e and are reflected, and the other ultrasonic wave is reflected. The propagation time until reception by the ultrasonic vibrator 54b is measured. Further, the ultrasonic waves emitted from the other ultrasonic vibrator 54b pass through the measurement flow paths 57a to 57f formed between the rectifying plates 56a, 56b, 56c, 56d, 56e and are reflected, and one of the ultrasonic waves is reflected. The propagation time until reception by the ultrasonic vibrator 54a is measured. From these differences in propagation time, the flow velocity of the gas in each of the measurement channels 57a to 57f is detected, and the flow rate of the gas passing through each of the measurement channels 57a to 57f is calculated.

Then, as shown in FIG. 3, the measuring unit 50 engages and positions one O-ring 59 with the engaging receiving portion 24a of the inlet buffer partition wall 24. Further, the remaining one O-ring 59 is engaged with and positioned with the engaging receiving portion 22a of the outlet buffer partition wall 22 of the case body 20. Next, the O-rings 59 and 59 are sandwiched between the inlet buffer partition wall 24 of the case body 20 and the inlet buffer partition wall 34 of the lid 30. Then, when the attachment of the lid 30 to the case body 20 is completed, the inlet communication holes 25a and 35a are formed (see FIG. 7). As a result, as shown in FIG. 8, the inlet portion 52a of the measuring unit 50 is positioned in the inlet buffer portion 16. Further, the outlet portion 52b of the measurement unit 50 is positioned in the outlet buffer portion 17. Then, the measurement circuit unit 53 of the measurement unit 50 is arranged in the central space portion 10c.
For convenience of explanation, the case 10 shows a structure for pulling out a connecting line connected to the measuring unit 50 and / or a structure for guiding a part of the gas to the outside in order to measure the pressure of the gas. However, it goes without saying that it may be provided as needed.

Next, a method for measuring the flow rate of gas will be described.
As shown in FIG. 3, by driving the valve body 41 of the shutoff valve 40 to open the inflow port 13, the gas flowing in from the inflow portion 11 enters the inlet flow path portion 14 of the inlet side space portion 10a from the inflow portion 13. Inflow to. Then, the gas flowing in from the inlet communication hole 25a of the first partition wall 25 flows into the inlet buffer portion 16. The gas that has flowed into the inlet buffer portion 16 flows into the tubular body 51 from the trumpet-shaped inlet portion 52a of the measuring unit 50. Further, the gas that has passed through the measurement channels 57a to 57f while being rectified along the five rectifying plates 56a to 56e is measured in propagation time via the ultrasonic waves emitted by the pair of ultrasonic vibrators 54a and 54b. .. Based on the measured propagation time, the flow rate of the gas passed by the central processing unit (CPU) mounted on the control circuit board 55 is calculated. Then, the gas that has passed through the measurement flow paths 57a to 57f flows out from the outlet portion 52b of the tubular body 51 to the outlet buffer portion 17, passes through the outlet communication hole 26a provided in the second partition wall 26, and passes through the outlet communication flow path 26a. After flowing into the unit 18, it flows out from the outflow unit 12.

As shown in FIGS. 12 to 15, the second embodiment is substantially the same as the first embodiment described above, except that the outlet flow path partition wall 21 and the outlet buffer partition arranged vertically in the case main body 20 are different. This is a point where the wall 22 forms an outlet buffer portion 17 that serves as an outlet side space portion 10b.
In particular, as shown in FIG. 14, the outlet flow path partition wall 21 is inclined so as to increase the cross-sectional area of the outlet buffer portion 17 toward the downstream side. Further, the outlet buffer partition wall 22 is provided with an engaging receiving portion 22a for supporting the outlet portion 52b of the measurement unit 50, which will be described later.

Further, as shown in FIG. 13, the lid 30 of the second embodiment has a front shape capable of covering the opening of the case body 20. Then, on the inward surface of the lid 30, the outlet flow path partition wall 21, the outlet buffer partition wall 22, the inlet flow path partition wall 23, the inlet buffer partition wall 24, the first partition wall 25, and the third partition wall are formed. The outlet flow path partition wall 31 and the outlet buffer partition wall 32, the inlet flow path partition wall 33 and the inlet buffer partition wall 34, and the first partition wall 35 and the third partition wall 37 are provided at positions where they abut against 27. Each is projected. Further, the outlet buffer partition wall 32 is provided with an engaging receiving portion 32a for supporting the outlet portion 52b of the measuring unit 50. An inlet communication hole 35a is formed in the first partition wall 35.

Next, as shown in FIG. 12, the measuring unit 50 is provided with an annular first flange portion 60 at a position corresponding to the engaging receiving portion 22a of the outlet buffer partition wall 22. Therefore, the outlet portion 52b of the measurement unit 50 is flush with the outward surface of the outlet buffer partition wall 22. As a result, there are advantages that the outflow of gas becomes smooth, the pressure loss is reduced, and the variation in the measured flow rate is reduced.
Since the other parts are the same as those of the above-described first embodiment, the same parts are assigned the same number and the description thereof will be omitted.

According to the present embodiment, the cross-sectional area of the outlet buffer portion 17 increases toward the downstream side. Therefore, there is an advantage that so-called gas release is improved, pressure loss can be reduced, gas flow in the measurement flow paths 57a to 57f can be improved, and variation in the measurement flow rate can be reduced.

As shown in FIGS. 16 to 17, the third embodiment is substantially the same as the second embodiment described above, and the difference is that it extends horizontally in the inlet flow path portion 14 and the inflow port 13 This is a case where the shielding plate 28 located between the inlet communication hole 25a and the inlet communication hole 25a is projected from the inward surface of the case body 20. The entrance communication hole 25a is arranged substantially in the center of the first partition wall 25.

According to the present embodiment, by installing the shielding plate 28, the pulsation of the gas can be reduced by temporarily blocking the gas flowing in from the inflow port 13.
Of course, the position, size, and shape of the shielding plate 28 can be appropriately selected as needed.
Since the other parts are almost the same as those of the second embodiment described above, the same parts are given the same number and the description thereof will be omitted.

The fourth embodiment is a case where the inlet flow path portion 14 of the inlet side space portion 10a and the central space portion 10c are communicated with each other, as shown in FIGS. 18 to 21.
That is, as shown in FIG. 18, the case 10 has a box shape, and the inflow portion 11 is arranged on one end side of the upper surface thereof, and the outflow portion 12 is arranged on the other end side.
Further, the case 10 is composed of a case main body 20 and a lid body 30. Then, at the inflow port 13 (see FIG. 22) located at the lower end of the inflow portion 11, a shutoff valve 40 provided with a valve body 41 is arranged in order to adjust the inflow of gas into the internal space of the case 10. ing.

As shown in FIG. 21, the internal space of the case body 20 has an outlet side space portion 10b on the left side of the case body 20 due to the outlet flow path partition wall 21 and the outlet buffer partition wall 22 projecting so as to be continuous vertically. Is formed.

The outlet side space portion 10b has a second partition wall 26 extending in the horizontal direction projecting from the inward surface of the case body 20 so that the outlet buffer portion 17 and the outlet flow path portion 18 are formed in two upper and lower stages. It is separated. The second partition wall 26 is provided with an outlet communication hole 26a for allowing gas to flow out. By providing the outlet communication hole 26a, a substantially orifice structure is formed, and an ultrasonic flowmeter capable of preventing erroneous measurement of the measuring unit due to pressure fluctuation can be obtained. Further, the outlet communication hole 26a is arranged inside the outlet portion 52b of the measurement unit 50, which will be described later, and the creepage distance is long.
The outlet communication hole 26a may be formed by post-processing after being molded by die casting as in the present embodiment, but is a part of the outlet communication hole 26a that opens to the front side as in the above-described embodiment. May be formed so as to be closed by a protrusion provided on the inward surface of the lid.
Further, the outlet buffer partition wall 22 is provided with an engaging receiving portion 22a for engaging and positioning the measurement unit 50, which will be described later, and is moved up and down on the facing surface of the opening edge portion of the engaging receiving portion 22a. A pair of fitting grooves 22c are provided. This is for attaching the spacer 61, which will be described later.
In addition, in order to attach the spacer, a pair of upper and lower engaging ridges may be provided on the facing surface of the opening edge portion of the engaging receiving portion 22a, and the actual joining may be performed. Further, it goes without saying that both may be assembled by making the facing surface of the opening edge portion of the engaging receiving portion 22a a flat surface and forming the shape so that the joint portion of the spacer straddles the flat surface. ..

Further, the case body 20 is integrally provided with a substantially L-shaped inlet flow path partition wall 23 so as to be continuous with the outlet flow path partition wall 21 on its inward surface, and a central space portion 10c is provided directly below the case body 20. It is formed. The front surface of the space portion surrounded by the outlet flow path partition wall 21 and the inlet flow path partition wall 23 is partitioned by an inner side wall 23a to form a storage portion 10e (FIG. 19).

The inlet side space portion 10a is partitioned by the inlet flow path partition wall 23 and the inlet buffer partition wall 24 projecting so as not to be continuous with the inlet flow path partition wall 23. The inlet side space portion 10a extends horizontally and is provided with a first partition wall 25 that is continuous only with the inlet buffer partition wall 24, so that the inlet flow path portion 14 and the inlet buffer portion 16 are formed. It is divided into upper and lower tiers. Therefore, the inlet flow path portion 14 and the central space portion 10c communicate with each other. An inlet communication hole 25a is formed in the first partition wall 25. By providing the inlet communication hole 25a, a substantially orifice structure is formed, and an ultrasonic flowmeter capable of preventing erroneous measurement of the measuring unit due to pressure fluctuation can be obtained. The inlet communication hole 25a is arranged inside the inlet portion 52a of the measurement unit 50, which will be described later, and has a longer creepage distance.
The inlet communication hole 25a may be formed by post-processing after being molded by die casting as in the present embodiment, but as shown in the above-described embodiment, one of the inlet communication holes 25a that opens to the front side. The portion may be formed so as to be closed by a protrusion provided on the inward surface of the lid.
Further, as shown in FIG. 21, the inlet buffer partition wall 24 is provided with an engaging receiving portion 24a for engaging and positioning the measuring unit 50 described later, and the opening of the engaging receiving portion 24a. A pair of upper and lower fitting grooves 24c are provided on the facing surfaces of the edges. This is for attaching the spacer 62, which will be described later.
Then, in order to attach the spacer, a pair of upper and lower engaging ridges may be provided on the facing surface of the opening edge portion of the engaging receiving portion 24a, and the actual joining may be performed. Further, it goes without saying that both may be assembled by making the facing surface of the opening edge portion of the engaging receiving portion 24a a flat surface and forming the shape so that the joint portion of the spacer straddles the flat surface. ..
Further, the inlet buffer partition wall 24 is provided with a notch portion 24b for guiding the liquid that has flowed in at the same time as the gas from the inlet buffer portion 16 to the central space portion 10c (FIG. 22). Therefore, even if a large amount of liquid flows into the inlet side space portion 10a, the liquid can be stored on the bottom surfaces of the inlet buffer portion 16 and the central space portion 10c, and the intrusion into the measurement unit 50 can be prevented.

As shown in FIGS. 18 and 19, the lid 30 is a plate-shaped body having a front shape capable of covering the opening of the case body 20.

As shown in FIG. 20, the measurement unit 50 is substantially the same as that of the above-described embodiment, and therefore, the same parts are designated by the same numbers and the description thereof will be omitted.

Then, as shown in FIG. 20, the measuring unit 50 is positioned by engaging with the engaging receiving portion 22a (FIG. 29) of the case body 20 via one O-ring 59 (FIG. 23). Further, the measuring unit 50 is positioned by engaging with the engaging receiving portion 24a of the case body 20 via one O-ring 59. Next, the spacer 61 is fitted into the fitting groove 22c of the outlet buffer partition wall 22, and the spacer 62 is fitted into the fitting groove 24c of the inlet buffer partition wall 24. Finally, the notch portion 24b is formed by attaching the lid body 30 to the case body 20 (see FIG. 22). As a result, as shown in FIG. 23, the inlet portion 52a of the measuring unit 50 is positioned in the inlet buffer portion 16. Further, the outlet portion 52b of the measurement unit 50 is positioned in the outlet buffer portion 17. Then, the measurement circuit unit 53 of the measurement unit 50 is arranged in the central space portion 10c.

The corners of the inlet side space portion 10a, the exit side space portion 10b, and the central space portion 10c are rounded surfaces in order to ensure a smooth flow of gas. Of course, the size of the are can be selected as needed. For example, the range of the radius of curvature of the rounded surface is preferably R0.5 to 30 mm. This is because if it is less than R0.5 mm, the defect occurrence rate at the time of casting increases remarkably, and if it exceeds R30 mm, the wall thickness becomes too thick and the manufacturing cost becomes high, which is not realistic.

As shown in FIGS. 24 to 32, the fifth embodiment is substantially the same as the fourth embodiment described above, and is roughly composed of a case 10, a shutoff valve 40, and a measuring unit 50. Therefore, the same parts will be described with the same numbers.

Since the shutoff valve 40 and the measurement unit 50 are almost the same as those in the above-described embodiment, the same parts are designated by the same numbers and the description thereof will be omitted.
However, the measuring unit 50 is connected to the engaging receiving portion 22a of the outlet buffer partition wall 22 and the engaging receiving portion 24a of the inlet buffer partition wall 24 shown in FIG. 29 via the O-rings 59 and 59 shown in FIG. 32. Are engaged. Further, as shown in FIG. 28, spacers 61 and 62 are arranged at the engaging receiving portion 22a of the outlet buffer partition wall 22 and the engaging receiving portion 24a of the inlet buffer partition wall 24, respectively.

As shown in FIGS. 24 and 25, the case 10 has a box shape and is composed of a case body 20 and a case body 20.

As shown in FIGS. 26 and 27, the case body 20 has a lid 30 joined and integrated with a screw (not shown) via a gasket 63.
In the present embodiment, the screwing pitch may be a predetermined distance in order to ensure the sealing property, for example, the screwing pitches adjacent to the sides may be set to a substantially equal distance, for example, 70 mm. This is to reduce the number of screws and increase productivity while ensuring sealing performance.

As shown in FIGS. 28 and 29, the case body 20 includes an inlet side space portion 10a, an exit side space portion 10b, and a central space portion 10c, as shown in FIGS. 28 and 29. It is divided into three spaces.

The entrance side space portion 10a is divided into upper and lower two stages by the inlet flow path portion 14 and the inlet buffer portion 16 by integrally projecting the horizontally extending first partition wall 25 into the case body 20. .. An inlet communication hole 25a is formed in the first partition wall 25. By providing the inlet communication hole 25a, a substantially orifice structure is formed, and an ultrasonic flowmeter capable of preventing erroneous measurement of the measuring unit due to pressure fluctuation can be obtained.
Further, the entrance side space portion 10a is connected to the inlet buffer portion 16 by integrally projecting the inlet buffer partition wall 24 which is continuous with the first partition wall 25 and extends in the vertical direction into the case body 20. The central space portion 10c is divided into left and right. Therefore, the inlet flow path portion 14 and the central space portion 10c communicate with each other. As a result, a part of the gas that has flowed in from the inflow port 13 flows into the central space portion 10c via the inlet flow path portion 14, and then flows into the inlet buffer portion 16.

As shown in FIG. 28, the outlet side space portion 10b is provided with the outlet buffer portion 17 and the outlet flow path portion 18 by integrally projecting the second partition wall 26 extending in the horizontal direction into the case body 20. It is divided into two upper and lower tiers. The second partition wall 26 is provided with an outlet communication hole 26a for allowing gas to flow out. By providing the outlet communication hole 26a, a substantially orifice structure is formed, and an ultrasonic flowmeter capable of preventing erroneous measurement of the measuring unit due to pressure fluctuation can be obtained.
Further, since the outlet communication hole 26a is arranged inside the outlet portion 52b of the measurement unit 50 described later, the creepage distance is long. A pressure sensor 45 is attached to the side wall of the outlet flow path portion 18.

As shown in FIGS. 30 and 31, the central space portion 10c has an inward projecting capacity of the inlet flow path partition wall 23 and the inner side wall 23a smaller than that of the fourth embodiment. This is to facilitate the flow of gas from the inlet flow path portion 14 to the central space portion 10c. According to this embodiment, there are advantages that the structure of the mold is simplified, die casting is facilitated, and the die casting material can be saved. Further, a relay connector 46 is provided on the inner side wall 23a.
Further, the side wall located on the lower side of the inlet flow path partition wall 23 is bulged outward to form the bulging portion 20a. Therefore, according to the present embodiment, there is an advantage that the bottom area of the central space portion 10c is increased and the amount of water that can store the invaded water is increased.

As shown in FIG. 27, the lid body 30 expands at a position facing the inlet flow path portion 14, the inlet buffer portion 16, the central space portion 10c, the outlet buffer portion 17, and the outlet flow path portion 18 of the case body 20. The protrusions 38a, 38b, 38c, 38d, and 38e are provided, respectively.
According to the present embodiment, since the bulging portions 38a, 38b, 38c, 38d, 38e are provided, the rigidity of the entire lid 30 is increased. In particular, the bulging portion 38c provided at a position facing the central space portion 10c not only avoids the collision between the lid 30 and the measurement circuit portion 53 (FIG. 31), but also substantially reduces the volume of the central space portion 10c. It has the advantage of increasing the amount of water stored.

In any of the above-described first to fifth embodiments, the inlet communication hole 25a communicating with the inlet buffer portion 16 is located above the inlet buffer portion 16. Therefore, the inlet communication hole 25a is located above the inlet portion 52a of the measurement unit 50 located in the inlet buffer portion 16. Then, the fluid to be measured that has flowed down from the inlet communication hole 25a into the inlet buffer portion 16 is separated into gas and moisture in the inlet buffer portion 16, and the moisture and the like are removed and managed.
(Example 1)

A simulation was performed for the first embodiment, and the flow rates in the six measurement channels 57a to 57f were obtained, and the pressure loss was obtained. The results of Example 1 are shown in the bar graph of FIG. 33 and the graph of FIG. 34.
The assumed ideal volumetric flow rate per layer was set to 1,000 (L / h).

As is clear from FIG. 33, the difference between the maximum flow rate (1,028 (L / h)) and the minimum flow rate (969 (L / h)) is 59 (L / h). The difference when the ideal flow rate was used as a reference was 5.9%, and it was confirmed that the variation of the present embodiment was smaller than the variation of the comparative example described later.
Further, as shown in FIG. 34, it was confirmed that the pressure loss was 185.3 (Pa), which was equal to or less than the in-house standard value (190 (Pa)).
(Example 2)

The second embodiment was simulated, and the flow rates in the six measurement channels 57a to 57f were obtained, and the pressure loss was obtained. The results of Example 2 are shown in the bar graph of FIG. 35 and the graph of FIG. 36.
The assumed ideal volumetric flow rate per layer was set to 1,000 (L / h).

As is clear from FIG. 35, the difference between the maximum flow rate (1,022 (L / h)) and the minimum flow rate (988 (L / h)) is 34 (L / h). The difference when the ideal flow rate was used as a reference was 3.4%, and it was confirmed that the variation of the present embodiment was smaller than the variation of the comparative example described later.
Further, as shown in FIG. 36, it was confirmed that the pressure loss was 159.7 (Pa), which was equal to or less than the in-house standard value (190 (Pa)).
(Example 3)

A simulation was performed for the third embodiment, and the flow rates in the six measurement channels 57a to 57f were obtained, and the pressure loss was obtained. The simulation results are shown in the bar graph of FIG. 36 and the graph of FIG. 37.
The assumed ideal volumetric flow rate per layer was set to 1,000 (L / h).

As is clear from FIG. 36, the difference between the maximum flow rate (1,016 (L / h)) and the minimum flow rate (972 (L / h)) is 44 (L / h). The difference when the ideal flow rate was used as a reference was 4.4%, and it was confirmed that the variation of the present embodiment was smaller than the variation of the comparative example described later.
Further, as shown in FIG. 37, it was confirmed that the pressure loss was 169.6 (Pa), which was equal to or less than the in-house standard value (190 (Pa)).
(Example 4)

A simulation was performed for the fourth embodiment, and the flow rates in the six measurement channels 57a to 57f were obtained, and the pressure loss was obtained. The simulation results are shown in the bar graph of FIG. 38 and the graph of FIG. 39.
The assumed ideal volumetric flow rate per layer was set to 1,000 (L / h).

As is clear from FIG. 38, the difference between the maximum flow rate (1,023 (L / h)) and the minimum flow rate (981 (L / h)) is 42 (L / h). The difference when the ideal flow rate was used as a reference was 4.2%, and it was confirmed that the variation of the present embodiment was smaller than the variation of the comparative example described later.
Further, as shown in FIG. 39, it was confirmed that the pressure loss was 177.6 (Pa), which was equal to or less than the in-house standard value (190 (Pa)).

Although the inlet flow path portion 14 and the central space portion 10c communicate with each other, the variation in the measured flow rate is small. This is because even if the gas flowing in from the inflow port 13 is pulsating, the gas staying in the central space 10c serves as a cushioning material, and the pulsation of the gas is absorbed before the inflowing gas passes through the inlet communication hole 25a.・ It is thought that this is because it is alleviated.
(Example 5)

A simulation was performed for the fifth embodiment, and the flow rates in the six measurement channels 57a to 57f were obtained, and the pressure loss was obtained. The results of Example 5 are shown in the bar graph of FIG. 40 and the graph of FIG. 41.
The assumed ideal volumetric flow rate per layer was set to 1,000 (L / h).

As is clear from FIG. 40, the difference between the maximum flow rate (1,033 (L / h)) and the minimum flow rate (973 (L / h)) is 60 (L / h). The difference when the ideal flow rate was used as a reference was 5.8%, and it was confirmed that the variation of the present embodiment was smaller than the variation of the comparative example described later.
Further, as shown in FIG. 41, it was confirmed that the pressure loss was 184.6 (Pa), which was equal to or less than the in-house standard value (190 (Pa)).

Although the inlet flow path portion 14 and the central space portion 10c communicate with each other, the variation in the measured flow rate is small. This is because even if the gas flowing in from the inflow port 13 is pulsating, the gas staying in the central space 10c serves as a cushioning material, and the pulsation of the gas is absorbed before the inflowing gas passes through the inlet communication hole 25a.・ It is thought that this is because it is alleviated.
(Comparison example)

An ultrasonic flowmeter simulating an existing current model was simulated, and the flow rates in the six measurement channels 57a to 57f were obtained. The simulation results are shown in the bar graph of FIG. 42.

As is clear from FIG. 42, the difference between the maximum flow rate (1,095 (L / h)) and the minimum flow rate (968 (L / h)) is 127 (L / h). The degree of variation based on the ideal flow rate was 12.7%.
Therefore, it was found that the variation in the measured flow rate according to each of the above-described examples is smaller than the variation in the measured flow rate according to the existing ultrasonic flowmeter.
(Example 6, Example 7)

Compared to the first embodiment and the fourth embodiment, low frequency (several Hz), medium frequency (about 20 Hz), and high frequency (several tens of Hz) sine wave pressure fluctuations are applied to a non-flowing gas via a speaker. Then, the fluctuation of the measured flow rate was measured and designated as Example 6 and Example 7. The measurement results of the measured flow rates of Examples 6 and 7 are shown in FIG.
The ideal measured flow rate in this embodiment is zero (L / h).

As is clear from FIG. 43, the average value of the measured flow rates is within ± 1 (L / h), which is smaller than the reference value 5 (L / h), which is the minimum value of the measured flow rates that must be detected. understood.
In particular, in Example 6 according to the fourth embodiment, it was found that the average value of the measured flow rates at the medium frequency was an order of magnitude smaller than the other average values. This is because the fluctuation of the measured flow rate fluctuates around the median, there is little deviation from the median, and there are few false positives.

As described above, the average value of the measured flow rates at the medium frequencies of Examples 6 and 7, especially Example 7, is significantly smaller than the average value of the other measured flow rates. This is because when the gas flows from the inflow port 13 into the inlet communication hole 25a, even if the pressure of the gas pulsates, the gas staying in the central space 10c absorbs the pulsation of the gas as a cushioning material.・ It is thought that this is to alleviate.
Therefore, it was found that the variation in the average value of the measured flow rates at low frequency, medium frequency, and high frequency can be reduced by appropriately selecting the position, shape, and volume of the central space portion 10c communicating with the inlet flow path portion 14.
(Example 8)

With respect to the fifth embodiment, a low frequency (several Hz), medium frequency (about 20 Hz) and high frequency (several tens of Hz) sine wave pressure fluctuations are applied to the non-flowing gas via a speaker to measure the flow rate. The fluctuation of the above was measured and used as Example 8. The measurement result of the measured flow rate of Example 8 is shown in FIG.
The ideal measured flow rate in this embodiment is zero (L / h).

As is clear from FIG. 44, the average value of the measured flow rates is within ± 1 (L / h), which is smaller than the reference value 5 (L / h), which is the minimum value of the measured flow rates that must be detected. understood.
In particular, in Example 8 according to the fifth embodiment, it was found that the average value of the measured flow rates at high frequencies was an order of magnitude smaller than the other average values. This is because the fluctuation of the measured flow rate fluctuates around the median, there is little deviation from the median, and there are few false positives.

The above-mentioned Examples 7 and 8 show the relationship between the measured flow rate and the time when a pressure fluctuation is applied when gas is not flowing through the gas meter, and the measured flow rate is 0 L / h. It is desirable to have. Since the measured flow rates of Examples 7 and 8 are within about ± 1 L / h, and in particular, the average measured flow rates of Example 8 are −0.04 L / h to −0.52 L / h. , It turned out that both have the same performance. Further, the gas meter must detect the flow rate exceeding 5 L / h, but it was found that the gas meter can sufficiently detect the flow rate within the above-mentioned error range.

As described above, the average value of the measured flow rates at the high frequency of Example 8 is significantly smaller than the average value of the other measured flow rates. This is because when the gas flows from the inflow port 13 into the inlet communication hole 25a, even if the pressure of the gas pulsates, the gas staying in the central space 10c makes the pulsation of the gas efficient as a cushioning material. It is thought that this is to absorb and alleviate the gas.
Therefore, it was found that the variation in the average value of the measured flow rates at low frequency, medium frequency, and high frequency can be reduced by appropriately selecting the position, shape, and volume of the central space portion 10c communicating with the inlet flow path portion 14.
(Example 9)

FIG. 45 shows a flow trail diagram in which the fluid flow is visualized by simulation for the first embodiment.

As is clear from FIG. 45, it was found that the gas flowing in from the inflow port 13 was squeezed when passing through the inlet communication hole 25a, then diffused again and flowed in from the inlet portion 52a of the measuring unit 50. Therefore, it was found that the pulsation of the gas is absorbed when the gas is squeezed and diffused through the inlet communication hole 25a, and the creepage distance is lengthened by detouring, and the pressure fluctuation of the gas is alleviated.
(Example 10)

FIG. 46 shows a flow trail diagram in which the fluid flow is visualized by simulation for the third embodiment.

As is clear from FIG. 46, the gas flowing in from the inflow port 13 collides with the shielding plate 28, diffuses and detours, is squeezed when passing through the inlet communication hole 25a, and then diffuses again to measure unit 50. It was found that the gas flowed in from the entrance portion 52a of the.

As is clear from the above flow path diagram, the pulsation of the gas is absorbed and relaxed by the gas colliding with the shielding plate 28 and bypassing it, or by squeezing and diffusing the gas by the inlet communication hole 25a. It turned out to be done.

It goes without saying that the present invention can be applied not only to city gas but also to the flow rate measurement of other gases.

10 Case 10a Inlet side space 10b Outlet side space 10c Central space 10d Water reservoir space 10e Storage part 11 Inflow part 12 Outflow part 13 Inflow inlet 14 Inlet flow path part 16 Inlet buffer part 17 Outlet buffer part 18 Outlet flow Road part 19 Intermediate buffer part 20 Case body 20a Swelling part 21 Outlet flow path partition wall 22 Outlet buffer partition wall 22a Engagement receiving part 23 Inlet flow path partition wall 23a Inner side wall 24 Inlet buffer partition wall 24a Engagement receiving part 24b Notch 25 1st partition wall 25a Entrance communication hole 26 2nd partition wall 26a Exit communication hole 27 3rd partition wall 28 Shielding plate 30 Lid 31 Exit flow path partition wall 32 Exit buffer partition wall 33 Entrance flow path partition wall 34 Entrance Buffer partition wall 34a Inlet communication hole 35 1st partition wall 36 2nd partition wall 36a Outlet communication hole 37 3rd partition wall 38a to 38e bulge 40 Shutoff valve 41 Valve body 45 Pressure sensor 46 Relay connector 50 Measurement unit 51 Cylindrical body 52a Inlet part 52b Outlet part 53 Measuring circuit part 54a Ultrasonic transducer 54b Ultrasonic transducer 55 Control circuit board 56a to 56e Straightening plate 57a to 56f Measuring flow path 60 First flange 61 Spacer 62 Spacer 63 Gasket

Claims (10)

With the case
The inlet buffer, which is a space partitioned on the upstream side of the case,
The outlet buffer portion, which is a partitioned space on the downstream side in the case,
It has a measuring unit that is housed in the case, has an inlet portion that communicates with the inlet buffer portion, and an outlet portion that communicates with the outlet buffer portion.
The gas flowing in from the inflow port communicating with the inflow portion of the case flows in from the inlet portion of the measuring unit communicating with the inlet buffer portion, circulates in the flow passage in the measuring unit, and communicates with the outlet portion. An ultrasonic flowmeter that measures the flow rate of gas passing through the measuring unit by flowing out of the outflow section through the outlet buffer section.
An inlet flow path portion that is partitioned from the inlet buffer portion by a partition wall projecting from the inward surface of the case and in which the gas flowing in from the inflow port flows down to the downstream side.
A central space portion arranged between the inlet buffer portion and the outlet buffer portion and accommodating the measurement unit is provided.
An ultrasonic flow meter characterized in that a gas that has flowed in from the inflow port and has flowed down to the downstream side of the inlet flow path portion flows into the inlet buffer portion through an inlet communication hole provided in the partition wall. The ultrasonic flow meter according to claim 1, wherein the inlet communication hole is arranged inside the inlet portion of the measuring unit. According to claim 1 or 2, the inlet buffer partition wall that partitions the inlet buffer portion and the central space portion is provided with a notch portion that allows the liquid that has flowed into the inlet buffer portion to flow out to the central space portion. The ultrasonic flowmeter described. Claims 1 to 3 characterized in that an outlet flow path portion is formed by projecting a partition wall having an outlet communication hole between the outlet buffer portion and the outflow portion of the case on the inward surface of the case. The ultrasonic flowmeter according to any one of the above items. The ultrasonic flow meter according to any one of claims 1 to 3, wherein the outlet buffer portion communicates directly with the outflow portion of the case. The ultrasonic flow meter according to claim 5, wherein the outlet buffer portion is formed so that the cross-sectional area increases toward the downstream side. It is characterized in that at least one of the opening edge portion of the inlet portion and the opening edge portion of the outlet portion of the cylinder of the measuring unit is arranged flush with the outward surface of the buffer portion. The ultrasonic flowmeter according to any one of claims 1 to 6. The ultrasonic flow meter according to any one of claims 1 to 7, wherein a shielding plate located between the inflow port and the inlet communication hole is provided on the inward surface of the case. The ultrasonic flow rate according to any one of claims 1 to 8, wherein the central space portion formed between the inlet buffer portion and the outlet buffer portion and the inlet flow path portion communicate with each other. Total. Claim 1 is characterized in that the front and back surfaces of the case are formed, and at least one of the side walls facing each other with the central space portion in between is provided with a bulging portion that bulges outward. 9. The ultrasonic flowmeter according to at least one of 9.

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