JPH09287995A - Flow rate measuring structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve measurement accuracy with pulsation in pressure, suppressed by providing buffer means respectively on an upstream of a first flowmeter, on a feedback flow path from the first flowmeter to a first pressure regulating valve and on a downstream of a second flowmeter. SOLUTION: Gas supplied to a flow path 21 keeps its pressure at a predetermined pressure by a pressure regulating valve 5 and flows through a flow path 8, a flowmeter 3 and a flow path 7 to a gas appliance of destination. A flowmeter 4 measures difference in pressures at an upstream flow path 41a and a downstream flow path 41b of an aperture 41 by a pressure gage 42 for calculating a flow rate in an arithmetic part 43. A pressure regulating valve 9 is provided on an upstream of the meter 4. A buffer means A comprising a mesh is provided on an upstream of a flowmeter 3 provided on a downstream of the regulating value 5 for supplying fluid of a predetermined pressure to the meter 3, a buffer means B comprising an aperture is provided on a flow path 6 for feeding back a pressure on downstream of the meter 3 to the regulating valve 5, and a buffer means C comprising a mesh is provided on a downstream of the meter 4, respectively, for suppressing the pulsation in pressure low.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow rate measuring structure for improving the measurement accuracy of a flow rate measuring means provided on the downstream side of a pressure adjusting means.

[0002]

2. Description of the Related Art For example, when measuring the flow rate of gas as fuel, a pressure measuring valve (flow rate measuring means) is provided downstream of a pressure adjusting valve (pressure adjusting means) to reduce the pressure to a predetermined pressure. After that, the flow rate of the gas is measured.

[0003]

However, when the pressure is adjusted by the pressure control valve, the pressure pulsates within a predetermined width.
This pressure pulsation has a drawback that it deteriorates the flow rate measurement accuracy of the flow rate measuring device.

The present invention has been made to solve the above-mentioned problems, and an object thereof is to suppress the pressure pulsation in the pressure adjusting means to be small, thereby improving the flow rate measuring accuracy in the flow rate measuring means. It is to provide a flow measurement structure.

[0005]

In order to achieve the above object, the invention according to claim 1 is characterized in that a flow rate measuring means is provided on the downstream side of the pressure adjusting means, and a pressure measuring means is provided on the upstream side of the flow rate measuring means. It is characterized in that a buffer means (A) for suppressing the pulsation is provided.

According to the second aspect of the present invention, the flow rate measuring means is provided on the downstream side of the pressure adjusting means, and the pressure adjusting means feeds back the pressure on the downstream side of the flow rate measuring means to thereby provide the same flow rate measuring means. Is configured to supply a fluid having a predetermined pressure, and a buffer means (B) for suppressing pressure pulsation is provided in the flow path for feeding back the pressure.

According to a third aspect of the present invention, the flow rate measuring means is provided on the downstream side of the pressure adjusting means, and the pressure adjusting means feeds back the pressure on the downstream side of the flow rate measuring means to thereby provide the same flow rate measuring means. Is configured to supply a fluid having a predetermined pressure, a buffer means (C) for suppressing pressure pulsation is provided on the downstream side of the flow rate measuring means, and a flow path on the upstream side of the buffer means (C) is provided. In addition, a flow path for feeding back the pressure is connected.

According to a fourth aspect of the present invention, a flow rate measuring means is provided on the downstream side of the pressure adjusting means, and the pressure adjusting means feeds back the pressure on the downstream side of the flow rate measuring means to thereby provide the same flow rate measuring means. Is configured to supply a fluid having a predetermined pressure, a buffer means (C) for suppressing pressure pulsation is provided on the downstream side of the flow rate measuring means, and a flow path on the downstream side of the buffer means (C) is provided. In addition, a flow path for feeding back the pressure is connected.

Further, in the invention according to claim 1, since the buffer means (A) for suppressing the pressure pulsation is provided on the upstream side of the flow rate measuring means, the flow rate measuring means has a fluid with a small pressure pulsation. Will flow in. Therefore,
It is possible to improve the measurement accuracy of the fluid in the flow rate measuring means.

According to the second aspect of the present invention, since the flow path for feeding back the pressure adjusting means from the downstream side of the flow rate measuring means is provided and the buffer means (B) is provided in this flow path, the flow rate measuring means is passed. Even if pulsation occurs in the pressure during the operation, the pulsation of the pressure is not directly fed back to the pressure adjusting means. That is, the pressure whose pulsation is reduced by the buffering means (B) is fed back to the pressure adjusting means. Therefore, the pulsation of the pressure in the pressure adjusting means can be suppressed to be small. Therefore, it is possible to supply the fluid having a small pressure pulsation to the flow rate measuring means, so that it is possible to improve the flow rate measuring accuracy in the flow rate measuring means.

In the invention according to claim 3, a buffer means (C) is provided on the downstream side of the flow rate measuring means, and a flow path for feedback to the pressure adjusting means is connected to the upstream side of the buffer means (C). Therefore, the pressure in which the pulsation is reduced by the buffering means (C) is fed back to the pressure adjusting means. Therefore, it is possible to supply the fluid having a small pressure pulsation to the flow rate measuring means, so that it is possible to improve the flow rate measuring accuracy in the flow rate measuring means.

In the invention according to claim 4, a buffer means (C) is provided on the downstream side of the flow rate measuring means, and a flow path for feedback to the pressure adjusting means is connected to the downstream side of the buffer means (C). Therefore, the pressure in which the pulsation is reduced by the buffering means (C) is fed back to the pressure adjusting means. Therefore, it is possible to supply the fluid having a small pressure pulsation to the flow rate measuring means, so that it is possible to improve the flow rate measuring accuracy in the flow rate measuring means. It should be noted that, rather than connecting the flow path for feedback to the upstream side of the buffer means (C) (the invention according to claim 3), connecting the same flow path to the downstream side of the buffer means (C) causes pressure pulsation. It is preferable to keep it small.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to FIGS. This embodiment shows a gas meter (flow rate measurement structure) for measuring the flow rate of a fuel gas (fluid) supplied from a gas cylinder.

In FIG. 4, reference numeral 1 denotes a gas meter. This gas meter 1 has a main body 2 to which two hoses 2a, 2a are connected, and a large flow rate measurement provided on one side of the main body 2. First flow rate measuring device (flow rate measuring means) 3 for
And a second flow rate measuring device (flow rate measuring means) 4 for measuring a small flow rate provided on the other side of the main body 2.

The main body 2 is constructed so that the gas in one of the two gas cylinders (not shown) can be automatically switched to the gas in the other gas cylinder before it is used up. The two hoses 2a, 2a are
The two gas cylinders are connected to each other. Further, after being automatically switched, a used gas cylinder is replaced with a new gas cylinder by, for example, a worker who regularly visits. At this time, the operator switches the direction of the lever 11 shown in FIGS.
When one of the gas cylinders we are currently using becomes empty, it will automatically switch to the new one.

In addition, as shown in FIG.
A first pressure adjusting valve (pressure adjusting means) 5 is provided. The first pressure control valve 5 has a diaphragm 52 configured to receive a force from the spring 51, and the valve body 53 is brought into contact with or separated from the valve seat 54 according to the movement of the diaphragm 52. It is supposed to do. Further, one chamber 52a located on the side having the spring 51 with the diaphragm 52 as a boundary is connected to the atmosphere side,
The other chamber 52b is connected to the downstream flow passage 7 (see FIGS. 1 and 5) of the first flow rate measuring device 3 via the second buffering means B and the first feedback flow passage 6. And
When the pressure of the flow passage 7 on the downstream side of the first flow rate measuring device 3 rises to a predetermined pressure, the diaphragm 52 moves to the left side in FIG. 2, the valve body 53 abuts the valve seat 54, and the valve seat 54
When the pressure drops below the specified pressure,
The diaphragm 52 moves to the right in FIG.
Is separated from the valve seat 54 and the valve seat 54 is opened.

The flow passage 21 on the upstream side of the valve seat 54 is connected to the gas cylinder side via a switching mechanism 22 for switching the gas cylinder to one side or the other side. The downstream side of the valve seat 54 is connected to the inflow port 3a of the first flow rate measuring device 3 via the flow path 8 as shown in FIGS. 1, 2, and 5. Therefore, if the pressure in the flow path 7 is lower than the predetermined pressure, the diaphragm 52 moves to the right in FIG. 2, the valve seat 54 opens, and the gas supplied to the flow path 21 flows from the valve seat 54 to the flow path 8 in the flow path 8. , Through the first flow rate measuring device 3 and the flow path 7 to the gas equipment (not shown) of the supply destination.

The gas is supplied in this way,
When the pressure in the flow path 7 reaches a predetermined pressure, this pressure is transmitted to the other chamber 52b through the feedback flow path 6 and the second buffer means B, and the diaphragm 52 moves to the left side in FIG. The seat 54 closes. Therefore, the gas does not flow from the valve seat 54 to the flow path 8, the first flow rate measuring device 3, and the flow path 7. Then, the pressure in the flow path 7 becomes lower than the predetermined pressure, and the valve seat 54 opens again as described above, and the flow path 7
Gas will be supplied to. Then, the pressure in the flow path 7 starts to rise.

As described above, the first pressure control valve 5 repeats opening and closing of the valve seat 54 in small increments, whereby the flow passage 7 is formed.
Will be maintained at a predetermined pressure. Therefore, the pressure of the gas flowing out from the first pressure control valve 5 to the flow path 8 has a pulsation with a predetermined width.

In the first flow rate measuring device 3, as shown in FIG. 4, the gas flowing from the inflow port 3a hits the target 32 through the nozzle flow path 31, and the fluid vibration generated at this time is detected by the pair of pressure sensors 33. , 33 to measure the flow rate. That is, since there is a fixed relationship between the frequency of fluid vibration generated when the gas hits the target 32 and the flow rate passing through the nozzle channel 31, the frequency of fluid vibration is detected by the pressure sensors 33 and 33. By doing so, the flow rate can be measured. Further, as shown in FIGS. 1, 4 and 5, a first buffering means A is provided at the inlet 3a. Further, an outlet 3b is provided on the downstream side of the target 32, and the outlet 3b is connected to the flow path 7. As shown in FIG. 5, the flow path 7 is connected to the other chamber 52b of the first pressure regulating valve 5 via the first feedback flow path 6 and the second buffering means B.

As shown in FIGS. 1, 3 and 6, the second flow rate measuring device 4 measures the pressure difference between the upstream flow passage 41a and the downstream flow passage 41b of the throttle 41 with the pressure gauge 42. The calculation unit 43 (see FIG. 1) calculates the flow rate based on the pressure difference. A second pressure adjusting valve 9 is provided on the upstream side of the second flow rate measuring device 4.

As shown in FIG. 3, the second pressure regulating valve 9 has a diaphragm 92 configured to receive the force from the spring 91, and this diaphragm 92 is provided.
The valve element 93 comes into contact with or separates from the valve seat 94 according to the movement of the valve. That is, one of the chambers 92a having the spring 91 is connected to the atmosphere with the diaphragm 92 as a boundary. Further, the other room 92b with the diaphragm 92 as a boundary also serves as a second feedback flow path 92b-1 as shown in FIGS. 1, 3 and 5, and via the third buffering means C, It is connected to the flow path 8.

The upstream side of the valve seat 94 is connected to the flow passage 21 via the flow passage 95 as shown in FIGS. 1, 3 and 5. Further, the downstream side of the valve seat 94 is connected to the upstream side flow path 41a of the second flow rate measuring device 4, as shown in FIG. The second pressure regulating valve 9 configured as described above maintains the pressure of the flow passage as the chamber 92b at a predetermined pressure by repeating opening and closing of the valve seat 94 in small increments. Therefore, the pressure of the gas flowing out from the second pressure regulating valve 9, that is, the valve seat 94 to the second flow rate measuring device 4 becomes pulsating with a predetermined width.

The first buffer means A is the first pressure adjusting valve 5
It is provided in the flow path 8 that connects the first flow rate measuring device 3 and the first flow rate measuring device 3, and is located at the inflow port 3a of the first flow rate measuring device 3. The first buffering means A is composed of a mesh (mesh), is less likely to resist the flow of gas, and absorbs the pulsation of pressure generated in the first pressure regulating valve 5. It is supposed to do.

The second buffering means B is provided in the first feedback flow path 6 and is located at the inlet of the first pressure adjusting valve 5 to the chamber 52b. The second buffering means B is constituted by a diaphragm, and the flow path 7
It is designed to absorb the pulsation that occurs in the. Also,
Since the first flow rate measuring device 3 has a structure for measuring the flow rate by the pressure fluctuation caused by the fluid vibration, the pressure pulsation in the flow path 7 is large. Therefore, the second buffer B is required to efficiently absorb the pressure pulsation. However, since the flow rate supplied to the room 52b through the first feedback flow path 6 can be small, the throttle diameter of the second buffer B can be reduced. Therefore, the pressure pulsation at the flow rate 7 can be efficiently absorbed by the second buffering means B.

The third buffer C is the second flow rate measuring device 4
Is provided on the downstream side of the second feedback channel 92b-1 and is further downstream of the second feedback channel 92b-1.
And, the third buffer means C is a mesh-like one.
In this configuration, the resistance of the gas flow is less likely to occur, and the pressure pulsation generated in the second flow rate measuring device 4 is absorbed. Also, the third buffer C
Is adapted to absorb the pulsation of the pressure generated in the first pressure regulating valve 5, and the pulsation is transmitted through the chamber 92a and the second feedback flow passage 92b-1 to the second pressure regulating valve 9 The second flow rate measuring device 4 is not adversely affected.

The set pressure of the first pressure adjusting valve 5 is
It is lower than the set pressure of the second pressure regulating valve 9. Therefore, when a large amount of gas is used and the pressure in the flow path 7 is low, both the first pressure adjusting valve 5 and the second pressure adjusting valve 9 open, so that the first flow rate measuring device 3 The flow rate can be measured at. Further, when the flow of gas becomes small and the pressure in the flow path 7 is high, only the second pressure adjusting valve 9 is opened, so that the flow rate can be measured only by the second flow rate measuring device 4. Since the second flow rate measuring device 4 is of a small flow rate type, it is possible to find a gas leak, for example.

Further, the first flow rate measuring device 3 and the second flow rate measuring device 4 are connected to the integrating section 10. Accumulator 1
0 is configured to integrate the flow rates measured by the first flow rate measuring device 3 or the second flow rate measuring device 4. Further, the integrating unit 10 is also configured to switch between measurement by the first flow rate measuring device 3 and measurement by the second flow rate measuring device 4.

In the gas meter 1 constructed as described above, as described above, the first pressure regulating valve 5 and the second pressure regulating valve 5 are provided.
Since the pulsation of the pressure of the pressure control valve 9 can be suppressed to be small, the flow rate measurement accuracy in the first flow rate measuring device 3 and the second flow rate measuring device 4 can be improved.

In the above embodiment, the third cushioning means C is provided on the downstream side of the connecting portion of the second feedback channel 92b-1 as shown in FIG. The buffer means C has a second feedback flow path 92b-
It may be provided in a portion closer to the second flow rate measuring device 4 on the upstream side of the first connecting portion. According to this structure, the pulsation of the pressure generated after passing through the second flow rate measuring device 4 can be more effectively absorbed by the third buffering means C, and the gas whose pulsation is reduced in this way can be obtained. The second pressure adjusting valve 9
Therefore, the pulsation of pressure in the second pressure control valve 9 can be further reduced. However, in order to prevent the pulsation of the pressure in the first pressure adjusting valve 5 from adversely affecting the second pressure adjusting valve 9, the third buffering means C shown in FIG. 1 is also provided in the same position. It is preferable. Further, the second feedback flow path 92b-1 in FIG. 1 may be provided with the one corresponding to the first buffering means B.

Further, in FIG. 1, the first buffering means A may be provided at any part of the flow path 8, and the second buffering means B may be provided at any part of the first feedback flow path 6. , The third buffer C is the second flow rate measuring device 4
It may be provided at any part in the flow path 92b on the downstream side of the. However, in order to make it less susceptible to pressure pulsation from other circuits, the first buffering means A is provided at a position close to the first flow rate measuring device 3, and the second buffering means B is provided for the first pressure adjustment. It is preferably provided at a position close to the valve 5.

Further, the first buffering means A and the third buffering means C are constituted by a net-like one, and the second buffering means B are constituted by a diaphragm-like one. , B, and C may be configured as an accumulator. In this case, there is an advantage that the pulsation of pressure can be absorbed more efficiently and the fluid resistance does not increase. Further, the first buffering means A and the third buffering means C may be configured to absorb pulsation by forming a part of the flow path thick. Also in this case, there is an advantage that the fluid resistance does not increase. Further, a plurality of mesh-shaped buffering means, diaphragm-shaped buffering means, accumulator-shaped buffering means, expanded diameter buffering means and the like may be combined in series or in parallel.

Furthermore, the third buffer C can be replaced by the first buffer A. That is, the third buffer C may be removed. In this case, the second feedback flow path 92b-1 may be connected between the first buffering means A and the first flow rate measuring device 3. However, the first pressure regulator 5
In order to avoid interference with the second flow rate measuring device 4 or the second pressure regulator 9, it is preferable to provide the third buffering means C.

[0034]

In the invention according to claim 1, the buffer means (A) for suppressing the pressure pulsation is provided upstream of the flow rate measuring means.
Therefore, the fluid having a small pressure pulsation flows into the flow rate measuring means. Therefore, it is possible to improve the measurement accuracy of the fluid in the flow rate measuring means.

According to the second aspect of the invention, since the flow path for feeding back the pressure adjusting means from the downstream side of the flow rate measuring means is provided and the buffer means (B) is provided in this flow path, the flow rate measuring means is passed. Even if pulsation occurs in the pressure during the operation, the pulsation of the pressure is not directly fed back to the pressure adjusting means. That is, the pressure whose pulsation is reduced by the buffering means (B) is fed back to the pressure adjusting means. Therefore, the pulsation of the pressure in the pressure adjusting means can be suppressed to be small. Therefore, it is possible to supply the fluid having a small pressure pulsation to the flow rate measuring means, so that it is possible to improve the flow rate measuring accuracy in the flow rate measuring means.

In the invention according to claim 3, a buffer means (C) is provided on the downstream side of the flow rate measuring means, and a flow path for feedback to the pressure adjusting means is connected to the upstream side of the buffer means (C). Therefore, the pressure in which the pulsation is reduced by the buffering means (C) is fed back to the pressure adjusting means. Therefore, it is possible to supply the fluid having a small pressure pulsation to the flow rate measuring means, so that it is possible to improve the flow rate measuring accuracy in the flow rate measuring means.

In the invention according to claim 4, a buffer means (C) is provided on the downstream side of the flow rate measuring means, and a flow path for feedback to the pressure adjusting means is connected to the downstream side of the buffer means (C). Therefore, the pressure in which the pulsation is reduced by the buffering means (C) is fed back to the pressure adjusting means. Therefore, it is possible to supply the fluid having a small pressure pulsation to the flow rate measuring means, so that it is possible to improve the flow rate measuring accuracy in the flow rate measuring means. It should be noted that, rather than connecting the flow path for feedback to the upstream side of the buffer means (C) (the invention according to claim 3), connecting the same flow path to the downstream side of the buffer means (C) causes pressure pulsation. It is preferable to keep it small.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a gas meter shown as an embodiment of the present invention.

FIG. 2 is a view showing a first pressure regulating valve of the gas meter and is a cross-sectional view taken along line II-II of FIG.

FIG. 3 is a view showing a second flow rate measuring device and a second pressure adjusting valve 9 of the gas meter, which is a cross section taken along line III-III in FIG. 4.

FIG. 4 is a front view of the gas meter.

FIG. 5 is a rear view of the gas meter.

6 is a diagram showing a second flow rate measuring device of the gas meter, which is a modeled diagram of the second flow rate measuring device shown in FIG. 3. FIG.

[Explanation of symbols]

1 gas meter 3 flow rate measuring means (first flow rate measuring instrument) 4 flow rate measuring means (second flow rate measuring instrument) 5 pressure adjusting means (first pressure adjusting valve) 6 flow path for feeding back pressure (first feedback) Flow path 9 Pressure adjusting means (second pressure adjusting valve) 92b-1 Flow path for feeding back pressure (second feedback flow path) A Buffer means (first buffer means) B Buffer means (second buffer) Means) C buffer means (third buffer means)

Claims (4)

[Claims] 1. A flow rate measuring structure characterized in that a flow rate measuring means is provided on the downstream side of the pressure adjusting means, and a buffer means (A) for suppressing pressure pulsation is provided on the upstream side of the flow rate measuring means. . 2. A flow rate measuring means is provided on the downstream side of the pressure adjusting means, and the pressure adjusting means feeds back the pressure on the downstream side of the flow rate measuring means to feed the fluid of a predetermined pressure to the flow rate measuring means. And a buffering means (B) for suppressing pressure pulsation is provided in the flow path for feeding back the pressure. 3. A flow rate measuring means is provided on the downstream side of the pressure adjusting means, and the pressure adjusting means feeds back the pressure on the downstream side of the flow rate measuring means, so that the fluid having a predetermined pressure is fed to the flow rate measuring means. Is provided, a buffer means (C) for suppressing pressure pulsation is provided on the downstream side of the flow rate measuring means, and the pressure is fed back to the flow path on the upstream side of the buffer means (C). A flow rate measuring structure characterized in that the flow paths are connected. 4. A flow rate measuring means is provided on the downstream side of the pressure adjusting means, and the pressure adjusting means feeds back the pressure on the downstream side of the flow rate measuring means so that the fluid having a predetermined pressure is fed to the flow rate measuring means. Is provided, a buffer means (C) for suppressing pressure pulsation is provided on the downstream side of the flow rate measuring means, and the pressure is fed back to the flow path on the downstream side of the buffer means (C). A flow rate measuring structure characterized in that the flow paths are connected.