JP2001208590A - Gas meter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To relax the change in a gas pressure being generated in front and rear chamber parts 1 and 6, improve the reliability of the detection result of a flow rate detection means 7, and at the same time suppress the influence of the fluctuation of the gas pressure to consumption equipment at the downstream side according to the opening/closing operation of a shutoff valve 5 or the like in a gas meter where a measurement channel 3 in that a flow rate detection means 7 for detecting the flow rate of a gas is arranged is inserted between the front chamber part 1 where the gas is allowed to flow in and the rear chamber part 6 where the gas is unloaded. SOLUTION: At least either of the chamber parts 1 and 6 is provided with a capacity-varying means 17 for changing the capacity in the chamber parts 1 and 6 according to the change in a gas pressure in the chamber parts 1 and 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a measuring flow path provided with flow rate detecting means for detecting a flow rate of a gas between a front chamber into which a gas flows and a rear chamber from which a gas is discharged. The present invention relates to a gas meter that is inserted into a gas meter.

[0002]

2. Description of the Related Art In gas meters, it has been proposed to use flow rate detecting means comprising a fluidic element or ultrasonic flow rate detecting means in place of a conventional membrane type flow meter. The flow rate detecting means detects the flow rate depending on the flow velocity. Further, in the gas meter, a plurality of gas flow paths are connected in parallel, one of the gas flow paths is provided with a flow rate detecting means, and the gas meter is opened and closed by an opening and closing operation of a shut-off valve provided in the plurality of gas flow paths. There has been proposed an apparatus that changes its own conductance and detects the overall gas flow rate based on the relationship between the detection result of a flow rate detection unit provided in one of a plurality of gas flow paths and the conductance of a gas meter.

[0003]

In such a gas meter, for example, when a sudden fluctuation of the gas pressure or a continuous pulsation of the gas pressure occurs in the anterior chamber into which the gas is introduced, a measurement provided with a flow rate detecting means is provided. The pressure of the gas flowing through the flow path changes, and there is a possibility that a detection error may occur particularly in the flow rate detecting means for detecting the flow rate depending on the flow velocity. In some cases, the shut-off valve may be temporarily closed in order to detect a small gas flow rate or leak detection. It is necessary to open the shut-off valve and flow gas instantaneously according to
As described above, it is difficult to reduce the operating time of the shut-off valve and to instantaneously send gas to the consumer equipment. Further, in a gas meter provided with a plurality of flow paths, a change in a consumed gas flow rate such as the start of operation of a consumer device connected on the downstream side causes the shut-off valves provided in the respective gas flow paths to open and close to operate the gas meter. Change the conductance,
In some cases, the total gas flow rate is calculated from the detection result of the flow rate detecting means. In such a gas meter, a sudden change in gas pressure in the front chamber or the rear chamber occurs due to the opening / closing operation of the shut-off valve. In addition to generating a detection error of the flow rate detecting means, there is a case where the gas consuming equipment provided on the downstream side is adversely affected. Therefore, the present invention, in such a gas meter, with a simple configuration, can reduce a sudden change in the gas pressure generated in the front chamber and the rear chamber or a continuous pulsation of the gas pressure, and detect the flow rate. It is an object of the present invention to improve the reliability of the detection result of the means and to suppress the influence of gas pressure fluctuation on downstream-side consuming equipment due to the opening / closing operation of a shutoff valve or the like.

[0004]

The features, functions and effects of the gas meter according to the present invention are as follows.

[Features] A measurement flow path in which a flow rate detecting means for detecting a flow rate of a gas is disposed is inserted between a front chamber portion into which a gas flows and a rear chamber portion through which a gas is discharged. A gas meter, wherein at least one of the chambers is provided with a capacity changing means for changing a capacity in the chamber in accordance with a change in gas pressure in the chamber.

[Operation / Effect] With the above configuration, a sudden pressure change generated when the shut-off valve provided on the upstream side of the flow rate detecting means is opened and closed, and a governor generated at a small flow rate. A change in gas pressure generated in the front chamber or the rear chamber, such as pressure vibration caused by hunting, can be absorbed by changing the capacity in the chamber by the capacity changing means. In addition, the shutoff valve may be temporarily closed in order to detect a small flow rate or a leak of gas.However, during the closing time, an increase in consumed gas flow rate may occur in downstream equipment, and the Although it is necessary to flow gas immediately in accordance with the consumption state, even in such a case, by providing the variable capacity means in the rear chamber, the gas pressure in the rear chamber due to the increase in the flow rate of the consumed gas can be reduced. Accompanying this, the capacity variable means reduces the capacity of the rear chamber,
The gas in the rear chamber can be sent to the downstream consuming equipment to gain time to open the shut-off valve. Therefore, by reducing the change in the gas pressure in the anterior chamber by the variable capacity means,
The adverse effect of the pressure change on the flow rate detecting means such as a flow meter connected downstream of the front chamber can be suppressed, and the reliability of the detection result of the flow rate detecting means can be improved. By mitigating the change in the gas pressure of the downstream side, the adverse effect of the pressure change on the gas equipment connected to the downstream side of the rear chamber can be suppressed, and even if the shutoff valve is temporarily closed, the downstream side A gas meter that can supply a certain amount of gas to the consumer equipment.

The features, functions and effects of the gas meter according to the second aspect of the present invention are as follows.

[Characteristic] In the gas meter according to the first aspect of the present invention, the capacity variable means is an elastic member having elasticity formed as at least a part of a wall constituting the chamber.

[Operation / Effect] As described above, by using an elastic member having elasticity, such as a plate made of an elastic material, for the whole or a part of the wall constituting the chamber, The elastic member having the elasticity can function as the capacity varying means. That is, based on the difference between the gas pressure inside the chamber and the atmospheric pressure of the outside air applied to the elastic member, the elastic member expands elastically to the outside, and the state of the elastic member with respect to the chamber changes. The expansion state changes with the gas pressure change in the, and the volume in the chamber can be changed,
The change in gas pressure generated in the chamber can be reduced. Therefore, with such a simple configuration, it is possible to configure a gas meter that can reduce a change in gas pressure generated in the chamber.

Further, for example, the wall member is partially formed to have a shape protruding outside the chamber, and an elastic member such as a plate-like member made of an elastic material is adhered to the inside of the protruding portion inside the chamber. By providing a communication hole in the wall member for communicating the space formed between the space member and the outside air, the elastic member can function as a variable capacity means. That is, the pressure in the space is always maintained at the atmospheric pressure by the communication hole, and based on the difference between the gas pressure in the chamber applied to the elastic member and the atmospheric pressure, the elastic member expands, and the state of the elastic member with respect to the chamber is changed. Changes, the expansion state changes with the change in gas pressure in the chamber, the capacity in the chamber can be changed, and the change in gas pressure generated in the chamber can be reduced. Therefore, with such a simple configuration, it is possible to configure a gas meter that can reduce a change in gas pressure generated in the chamber,
Further, since the elastic member serving as the variable capacity means is provided in the wall member, interference between the elastic member whose state changes and the outside can be prevented, and damage to the membrane member can be prevented.

The features, functions and effects of the present invention according to claim 3 are as follows.

[Features] In the gas meter of the present invention according to any one of claims 1 to 2, the capacity variable means is
The bellows member is formed as at least a part of a wall constituting the chamber and has a bellows structure.

[Operation / Effect] As described above, the bellows member is formed, for example, by molding a resin or rubber or the like into a cylindrical shape having a bellows structure on the outer peripheral portion or a disk shape having a corrugated bellows structure in a concentric shape. By using it for part or all of the wall constituting the chamber, it is possible to function as a variable capacity means. That is, the bellows member is subjected to the gas pressure in the chamber and the atmospheric pressure of the outside air, and expands and contracts due to a balance between them. It can be changed, and the change in gas pressure generated in the chamber can be reduced. Therefore, with such a simple configuration, it is possible to configure a gas meter that can reduce a change in gas pressure generated in the chamber.

The features, functions and effects of the present invention according to claim 4 are as follows.

[Features] In the gas meter of the present invention according to any one of claims 1 to 3, a plurality of gas flow paths are provided between a front chamber portion into which gas flows and a rear chamber portion through which gas is discharged.
A plurality of gas flow paths are arranged in parallel, and the flow rate detection means is arranged in one of the plurality of gas flow paths to be the measurement flow path, and the conductance of the other gas flow paths is the Forming a predetermined ratio with respect to the conductance of the measurement flow path, providing a flow path blocking mechanism capable of individually blocking the plurality of gas flow paths at an inlet of each gas flow path; Under a predetermined condition relating to the flow rate of the gas flowing therethrough, a flow path blocking mechanism provided in a gas flow path other than the measurement flow path can be opened and closed.

[Operation / Effect] By configuring the gas meter as described above, the gas flows at a predetermined distribution ratio to the flow rate detecting means with respect to the gas flow rate at which the flow rate is measured, so that the flow rate detecting means It is possible to measure the gas flow rate higher than the detected gas flow rate. That is, since the flow rate detected by the flow rate detection means arranged in the measurement flow path can be converted into the total gas flow rate based on the distribution ratio between the gas flow paths, the gas flow rate exceeding the detection upper limit flow rate of the flow rate detection means can be measured. In addition, since the flow measurement lower limit flow rate can be increased, the flow measurement accuracy can be maintained high. That is, by arranging the flow rate detection means in the measurement flow path, the conductance of the other gas flow path is set to a predetermined ratio with respect to the conductance of the measurement flow path,
When the gas flows through the plurality of gas flow paths at the same time, the gas flows through each gas flow path at the predetermined ratio. Therefore,
If a flow path cutoff mechanism is provided at the entrance of each gas flow path and the flow path cutoff mechanism is opened and closed by the cutoff control means, the gas amount having a predetermined distribution ratio among the gas amounts flowing to the gas meter is detected. This allows the total gas flow to be measured. When all the other gas flow paths are closed, the detected gas flow rate is naturally the total gas flow rate. In this case, the distribution ratio is naturally one. In addition, since the flow rate measurement range can be expanded to a larger flow rate side than the detection upper limit flow rate of the flow rate detection means, even if the flow rate detection range is reduced, the flow rate measurement range can be maintained large and the detection lower limit flow rate can be increased. Therefore, the accuracy near the detection lower limit flow rate can be improved.

In such a gas meter, the start of the operation of the consuming equipment connected downstream or a change in the amount of consumed gas causes a fluctuation in the pressure particularly in the rear chamber. Such pressure fluctuations may adversely affect consumer equipment connected downstream of the gas meter. For example, when the gas consumption of the consumer equipment increases and the gas flow rate increases, the pressure drop in the rear chamber is detected and the shut-off valve is opened / closed to reduce the conductance of the gas meter. During the delay time until the completion, the capacity of the rear chamber can be reduced by the capacity variable means provided in the rear chamber, gas can be sent to the consuming equipment, and the shut-off valve can operate. You can take the time. Accordingly, a plurality of gas flow paths are provided, and the flow rate measurement range of the flow rate detection means can be expanded by changing the conductance of the gas flow paths by opening and closing operations of the respective shut-off valves. And a gas meter that can send gas in a manner that smoothly responds to changes in the gas consumption of the consuming equipment can be configured.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a gas meter according to the present invention will be described. The following example relates to a fluid vibration type flow meter using a fluidic element as a flow rate detecting means.

In the example shown in FIG. 1, a front chamber 1 having a gas introduction section 1a connected to a gas supply pipe and a rear chamber 6 having a gas delivery section 6a connected to a downstream supply pipe are provided with a gas. The connection is made with the flow path 2. The gas flow path 2 is composed of a single measurement flow path 3 and a bypass flow path 4 attached to the same.
The bypass flow path 4 is formed by two flow paths of a first bypass flow path 4A and a second bypass flow path 4B. And each gas flow path 2
On the inlet side of the valve, shutoff valves 5A, 5B,
5C are provided respectively. A fluid vibration type flow rate detecting means 7 using a fluidic element is arranged in the measurement flow path 3 so as to detect the total amount of gas flowing through the measurement flow path 3. Conductance setting means 11 having an orifice nozzle is provided in each of the bypass flow paths 4A and 4B, and the conductance is set to the conductance setting means 11 provided in the first bypass flow path 4A with respect to the conductance of the measurement flow path 3. It is convenient to set the conductance of the first orifice 11A provided so as to be three times and the conductance of the second orifice 11B provided in the conductance setting means 11 provided in the second bypass channel 4B so as to be 15 times. That is, based on the flow path resistance of the fluidic element, the opening diameter of the orifice nozzles of both orifices 11A and 11B provided in the conductance setting means 11 provided in both the bypass flow paths 4A and 4B is set. Thus, the total conductance of the gas flow path 2 including the measurement flow path 3 in which the flow path blocking mechanism 5 is opened in the n-th measurement mode is 2K times (K is a natural number) the conductance of the measurement flow path 3 and is an integer multiple. It is configured so that For example, the conductance in the primary measurement mode using only the measurement channel 3 and the second measurement mode using the measurement channel 3 and the first bypass channel 4A by opening the shutoff valve 5B provided in the first bypass channel 4A. The ratio of the total conductance to the total conductance in the third measurement mode using the measurement flow path 3 and the second bypass flow path 4B by opening the shutoff valve 5C provided in the second bypass flow path 4B is 1: 4: 16. It is configured as follows.

When the conductance in each measurement mode is set as described above, for example, as shown in FIG. 2, a flow counter 15 as a flow integrating means 14 for integrating the flow rate from the measurement signal of the flow detecting means 7 is provided. Prepare for each measurement mode. That is, the value of the data register 16 which receives the flow rate detection pulse sent from the flow rate detecting means 7 is converted into a detected weighed value, and this is used as the measured weighed value, and the first flow counter 15A corresponding to the primary measurement mode is used.
Is integrated. Then, the other flow counter 15 multiplies the value obtained by dividing the total conductance in the measurement mode by the conductance of the measurement flow path. If the ratio of the total conductance of each measurement mode is 2K times as described above, the binary data stored in the first flow counter 15A corresponding to the primary measurement mode is converted to the second data corresponding to the secondary measurement mode. The measured flow value in the second measurement mode can be integrated simply by shifting and transferring the digit to the flow counter 15B, and the third flow counter 15C corresponding to the tertiary measurement mode has the second flow rate stored in the second flow counter 15B. It shifts and transfers the radix data. In other words, the binary data stored in the (n-1) th flow counter corresponding to the (n-1) th measurement mode may be shifted by a digit and transferred to the nth flow counter corresponding to the nth measurement mode. In this way, the measured flow value in each measurement mode can always be integrated regardless of whether the measurement mode is selected. Therefore, the measurement flow value can be read immediately after selecting the measurement mode, and when switching the gas flow path, the measurement flow value in the measurement mode before switching and the measurement flow value after switching are simultaneously referred to. Since it is possible, the correction at this point becomes easy, and the calculation load becomes extremely low.

Further, the pulse data may be added to the digit shifted according to the measurement mode corresponding to each flow counter. When the ratio of the total conductance in each measurement mode is set to 2K times as described above, only one flow counter 15 is provided, and the value stored in the data register 16 is converted into a measured flow value. Then, the number of shift digits may be set according to the measurement mode and added to the flow counter 15. In this way, the calculation load can be reduced. The flow measurement is
What is necessary is just to read from the flow counter corresponding to each measurement mode.

More specifically, the stationary gas supply pressure outside the lamp is about 981 Pa (100 mmAq), and the pressure loss outside the lamp up to the gas meter is about 49 Pa (5 mmAq).
Under the design conditions described above, the oscillation frequency for the gas flow rate of the fluidic element of 10 L / h was set to 2 Hz, and the maximum pressure loss of the flow rate detection means 7 was about 127 Pa (13 mmAq).
The flow rate detection range when set to 10 to 250 L / h
(The oscillation frequency is 2 to 50 Hz). In this case, the opening diameter of the orifice nozzle provided in the first bypass passage 4A is 5.04 mm, and the opening diameter of the orifice nozzle provided in the second bypass passage 4B is 10.08 mm. With such a configuration, in the primary measurement mode in which only the shutoff valve 5A of the measurement flow path 3 is opened, the flow rate measurement range is 10 to 250 L.
/ H, and in the secondary measurement mode in which the shut-off valve 5B provided in the first bypass flow path 4A is opened together with the shut-off valve 5A of the measurement flow path 3, the flow rate is measured in accordance with the flow rate detection range of 10 to 250 L / h. The range is 40-1000 L / h,
Similarly, in the third measurement mode in which the cutoff valve 5C of the second bypass flow path 4B is opened together with the cutoff valve 5A of the measurement flow path 3, the flow rate measurement range is 160 to 4000 L / h. As a result, the flow rate measurement range of the gas meter having the first to third measurement modes is 10 to 4000 L / h under the conditions of the oscillation frequency and the pressure loss.

With the above configuration, between the primary measurement mode and the secondary measurement mode, the flow rate measurement range includes 250 L / h, which is the upper limit of the flow rate detection in the primary measurement mode, and the flow rate detection means 7 in the secondary measurement mode. 40 to 250 L / h between the flow measurement lower limit of 40 L / h corresponding to the flow detection lower limit
And the upper limit of the flow rate measurement corresponding to the flow rate detection upper limit of the flow rate detector 7 in the secondary measurement mode is 1000 L even between the secondary measurement mode and the tertiary measurement mode.
/ H and the lower limit of the flow rate measurement of 160 L / h corresponding to the lower limit of the flow rate detection of the flow rate detecting means 7 in the third measurement mode, there is an overlapping measurement range of 160 to 1000 L / h. Therefore, within this overlapping measurement range, there will be two or more measurement modes that can measure the flow rate,
In this overlapping measurement range, the flow rate can be measured in the previous measurement mode regardless of the direction of the flow rate change, so that the opening / closing operation of the flow path blocking mechanism 5 does not need to be performed.

The gas meter is provided with shut-off control means 9 for switching the gas flow path 2 in order to sequentially switch between the first to third measurement modes. The shut-off control means 9 does not close the shut-off valve 5A provided in the measurement flow path 3 at the time of measuring the flow rate, and in predetermined measurement conditions, in the primary measurement mode, shut-off valves 5B and 5C provided in the bypass flow path 4. Are closed, the shutoff valve 5C provided in the second bypass flow path 4B is closed to switch to the secondary measurement mode, and the shutoff valve 5B provided in the first bypass flow path 4A is opened to switch to the tertiary measurement mode. Therefore, the shut-off valve 5B provided in the first bypass flow path is closed, and the shut-off valve 5C provided in the second bypass flow path 4B is opened. In other words, when the detected flow rate detected by the flow rate detecting means 7 reaches the upper limit of the flow rate detection, the bypass flow path 4 having the larger conductance is sequentially opened, and the other bypass flow paths 4 are closed. Conversely, when the flow rate detected by the flow rate detection means 7 reaches the flow rate detection lower limit, the bypass flow path 4 is sequentially switched to one having a smaller conductance. In other words, the combination of the gas flow paths is switched so that the measurement mode sequentially shifts to the measurement mode having a large total conductance as the flow rate increases, and the measurement mode sequentially shifts to the measurement mode with a small total conductance as the flow rate decreases.

Further, in the above-mentioned configuration, an outlet pressure detecting device capable of detecting an outlet channel pressure as a gas meter outlet pressure for supplying gas to the downstream side in the rear chamber portion 6 corresponding to the outlet channel of the gas channel 2. Preferably, means 8 are provided. Then, as an input signal to the shutoff control means 9, in addition to the weighing signal from the flow rate detection means 7, a pressure signal from the outlet pressure detection means 8 may be input. In this case, the determination of opening / closing of each flow path blocking mechanism 5 by the blocking control means 9 may be further performed as follows.

Here, the decision to open and close the flow path blocking mechanism 5 provided in the bypass flow path 4 is basically based on two criteria. The first criterion is based on the weighing signal from the flow rate detecting means 7, and the second criterion is based on the pressure signal from the outlet pressure detecting means 8.

The first criterion relates to the flow rate detection lower limit of the flow rate detecting means 7. When it is detected that the flow rate measurement lower limit in the measurement mode has been reached, the measurement mode is set to the lower measurement mode. Is closed or opened so as to shift to. For example, when the lower limit of the flow rate measurement (160 L / h in the above example) is detected in the third measurement mode, the shutoff valve 5C provided in the second bypass flow path 4B is closed and at the same time,
That is, the cutoff valve 5B provided in the first bypass flow path 4A is opened to shift to the secondary measurement mode.

The second criterion relates to the upper limit of the measurement flow rate range in each measurement mode. When the upper limit of the flow rate measurement is determined by the pressure loss of the gas meter, the transition to the higher-order measurement mode may be determined based on the weighing signal, but it is preferably based on the lower limit value of the outlet flow path pressure. In other words, when it is detected that the outlet flow pressure detected by the outlet pressure detecting means 8 has become equal to or lower than the preset lower limit pressure, the bypass flow path 4 is set so that the measurement mode is immediately shifted to the higher-order measurement mode. Is opened or closed. For example, in the secondary measurement mode, the outlet flow path pressure is set to the lower limit pressure (for example, about 98
When it is detected that the pressure has become equal to or less than 1 Pa, that is, 100 mmAq), the shutoff valve 5C provided in the second bypass flow path 4B is immediately opened, and at the same time, the first bypass flow path 4A
In this case, the shut-off valve 5B provided for the above is closed, the flow path is switched, and the mode shifts to the third measurement mode. According to this configuration, the shutoff control means 9 can also function as a safety device when a large amount of gas leaks downstream of the gas meter.
For example, when the outlet flow path pressure is reduced to about 294 Pa (30 mmAq) or less, all the flow path shutoff mechanisms 5, that is, the shutoff valves 5A provided in the measurement flow path 3 and the cutoff valves 5B and 5C provided in the bypass flow path 4 are provided. Is closed. With this configuration, when the flow path pressure on the downstream side of the gas meter drops abnormally, the gas supply from the gas meter is completely stopped, and safety can be maintained.

As described above, by switching the flow path to the higher-order measurement mode based on the outlet flow pressure, the linearity of the weighing signal with respect to the flow rate on the large flow rate side is guaranteed. Then, the flow rate detection range of the flow rate detection means 7 can be expanded to the large flow rate side. For example, when the gas meter inlet pressure of the gas is increased, a margin is given to the pressure loss, which is the design standard of the flow rate detecting means 7. That is, the linearity on the large flow rate side is guaranteed or corrected up to twice the flow rate detection range set on the basis of the pressure loss in the measurement signal of the flow rate detection means 7, and the outlet flow If the road pressure does not fall below the lower limit pressure, for example, if a metering signal of 2 to 50 Hz is used, if there is linearity, a metering signal of 2 to 100 Hz is used, and the flow rate measurement range of the gas meter is set to 10 to 8000 L. / H
It can be expanded to Here, the switching of the flow path to the higher-order measurement mode is determined only by the outlet flow path pressure without depending on the upper limit of the weighing signal.

Further, if the judgment on the switching of the flow path by the cutoff control means 9 is made with a delay by providing a delay time, the transient disturbance accompanying the flow rate change can be excluded from the judgment. For example, when the output signal from the flow rate detecting means 7 or the outlet pressure detecting means 8 to be a condition for switching the flow path is received, except when the above-mentioned outlet flow path pressure becomes equal to or lower than the guaranteed pressure on the downstream side. Thereafter, only when the condition for switching the flow path is satisfied even after the elapse of the preset delay time, it is determined that the switching of the flow path is performed. The delay time may be a time until the flow rate or the pressure is substantially settled. With this, if the delay time is set to about 1 to 10 seconds, the pressure vibration caused by noise of 10 Hz or less in the sound waves generated when the flow path shut-off mechanism 5 is opened and closed for switching the flow path will be reduced. It is possible to prevent the detection means 7 from detecting the fluid vibration together with the detection.

The structure of a gas meter having a wider flow rate measurement range than before without deteriorating the measurement accuracy on the small flow rate side has been described above. In particular, a fluid vibration type flow rate using such a fluidic element has been described. In the gas meter provided with the detecting means 7, since the fluidic element detects the flow rate based on the flow velocity of the gas, there is a possibility that a detection error may occur due to a fluctuation in the pressure of the supplied gas. Therefore,
The gas meter of the present invention is provided with an elastic member 17a which is a rubber plate-like member having a thickness of 0.5 mm as a part of the wall surface constituting the front chamber portion 1. When the gas pressure in the front chamber 1 rises above the atmospheric pressure, the elastic member 17a elastically expands outward due to a pressure difference from the atmospheric pressure. It functions as capacitance variable means 17 for elastically changing the capacitance. Therefore, it is possible to suppress the adverse effect of the pressure change on the flow rate detecting means 7 connected to the downstream side of the front chamber 1 and improve the reliability of the detection result of the flow rate detecting means 7.

Further, the gas meter of the present invention has a rear chamber 6
Also, similarly to the front chamber, an elastic member 17a, which is a rubber plate-like member having a thickness of 0.5 mm, similar to the front chamber 1, is provided as a part of the wall surface constituting the rear chamber 6, In the rear chamber 6, the elastic members 17a are provided at two places (not shown). Also in the elastic member 17a of the rear chamber part 6,
It acts as a capacity variable means 17 for elastically changing the capacity of the front chamber by the gas pressure of the rear chamber 6, and when the gas consumption of the consuming equipment increases and the gas flow rate increases, the pressure of the rear chamber 6 increases. When the lowering is detected, the shut-off valve 5 is opened / closed to reduce the conductance of the gas meter. However, during a delay time until the shut-off valve 5 completes the opening / closing operation, the elastic member 17a provided in the rear chamber 6 is operated by the elastic member 17a. By restoring, the capacity of the rear chamber 6 can be reduced by using this as a buffer, and gas can be sent to the consuming equipment, so that there is enough time for the shut-off valve 5 to operate. For example, when a small flow rate of gas is being supplied, the gas consumption on the consuming device side suddenly decreases to 1800 L / h in a state in which the shutoff valve 5 is temporarily fully closed.
When the output signal from the outlet pressure detecting means 8 becomes equal to or lower than the lower limit pressure (for example, about 981 Pa, that is, 100 mmAq), it takes about 0.3 seconds to open the shut-off valve 5. The load fluctuation occurs in about one second. In such a case, the elastic member 17a of the rear chamber 6 has been expanded by 0.05 L by then, and if the rear chamber 6 has a buffer of 0.05 L, the elastic member 1
By the gas supply by the restoration of 7a, a margin time of 0.3 seconds for the opening operation of the shutoff valve 5 can be obtained.

Further, a rectifying plate 10 made of a perforated plate having an opening cross-sectional area set in accordance with the conductance ratio of each gas flow path 2 is disposed at the entrance of each gas flow path 2 in the front chamber 1. If it does, flow distribution to each gas flow path 2 becomes accurate,
The measurement accuracy of the gas meter can be improved. In addition, the provision of the rectifying plate 10 is advantageous because disturbance introduced from the upstream side of the gas meter can be suppressed.

[Another Embodiment] Another embodiment of the flow switching gas meter according to the present invention, which has not been described in the above embodiment, will be described below.

<1> In the above-described embodiment, the elastic member 17 which is a rubber plate-like member as the capacity varying means 17
Although the configuration in which “a” is provided in the front chamber portion 1 and the rear chamber portion 6 has been shown, the capacity variable means 17 can be configured as follows. As shown in FIG. 3A, a corrugated plate 17b having, for example, concentric corrugated irregularities on the plate surface may be provided as the capacitance varying means 17 instead of the elastic member 17a of the above embodiment. Absent. With this configuration, the corrugated sheet 1
7b expands to the outside due to, for example, the gas pressure in the rear chamber 6, so that, similarly to the above-described elastic member, the capacity variable means 17 elastically changes the capacity of the chamber based on the change in gas pressure. Can work. Further, such a corrugated plate 17b is preferably made of rubber, but can be separately made of resin, a thin metal plate, or the like.

As shown in FIG. 3B, an elastic member 17c, which is a rubber plate-like member having a raised central portion, is provided in the chamber of the rear chamber 6, for example, as the capacity varying means 17. The portion is provided in a state of being stuck to the inner wall of the rear chamber portion 6, and a communication hole 6 d that communicates the space 6 c formed between the elastic member 17 c and the wall of the rear chamber portion 6 with the outside air is provided. With this configuration, the pressure of the space 6c is always maintained at the atmospheric pressure by the communication hole 6d, and the elastic member 17c is set on the basis of the difference between the gas pressure applied to the elastic member 17c in the rear chamber 6 and the atmospheric pressure. 1
7c changes, the expansion state of the elastic member 17c changes according to the gas pressure change in the rear chamber portion 6, and the rear chamber portion 6c changes.
Can be changed, and can function as capacity changing means 17 for reducing a change in gas pressure generated in the chamber. Further, since the elastic member 17c is provided inside the rear chamber portion 6, damage to the elastic member 17c can be prevented.

Further, as shown in FIG. 3C, a bellows member 17d may be provided as the capacity changing means 17 instead of the elastic member. This bellows member 17d
The gas pressure in the rear chamber 6 and the atmospheric pressure of the outside air
The rear chamber 6
The expansion and contraction state changes in accordance with the gas pressure change in, the capacity in the chamber can be changed, and it can function as the capacity variable means 17 for alleviating the gas pressure change generated in the chamber. Further, such a bellows member 17d is preferably made of rubber, but can be separately made of resin, a thin metal plate, or the like.

<2> In the above-described embodiment, an example has been described in which the fluid vibration type flow detecting means 7 using a fluidic element is disposed in the measurement flow path 3. The present invention is not limited to this, and may be an ultrasonic flow meter, or a conventionally used membrane gas flow meter.

<3> In the above embodiment, the configuration in which the bypass flow path 4 is provided has been described.
A capacity variable means 17 for elastically changing the capacity according to a change in the gas pressure in the chamber may be provided in the front chamber or the rear chamber of the gas meter having only the gas chamber.

[Brief description of the drawings]

FIG. 1 is a configuration explanatory view showing the configuration of an example of a gas meter according to the present invention.

FIG. 2 is a configuration explanatory view illustrating an example of a flow counter in the gas meter according to the present invention.

FIG. 3 is an explanatory diagram showing a configuration of a variable capacity means in another embodiment of the gas meter according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Front chamber part 2 Gas flow path 3 Measurement flow path 5 Flow path shutoff mechanism 6 Rear chamber part 7 Flow rate detection means 8 Outlet pressure detection means 9 Shutoff control means 15 Flow counter 17 Capacity variable means

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Hiroshi Matsushita 4-1-2, Hirano-cho, Chuo-ku, Osaka-shi, Osaka Inside Osaka Gas Co., Ltd. (72) Shuichi Okada 4-chome, Hirano-cho, Chuo-ku, Osaka-shi, Osaka No. 1-2 F-term in Osaka Gas Co., Ltd. (reference) 2F030 CC13 CD17 CE02 CF05 CF09 2F031 AB01 AC03 AD01

Claims (4)

[Claims] 1. A measuring flow path in which a flow rate detecting means for detecting a flow rate of a gas is disposed between a front chamber portion into which a gas flows and a rear chamber portion through which a gas is discharged. A gas meter, comprising: at least one of the chambers having a variable capacity means for changing a capacity in the chamber in accordance with a change in gas pressure in the chamber. 2. The gas meter according to claim 1, wherein the capacity variable means is an elastic member having elasticity formed as at least a part of a wall constituting the chamber. 3. The gas meter according to claim 1, wherein the variable capacity means is a bellows member formed as at least a part of a wall constituting the chamber and having a bellows structure. 4. A plurality of gas flow paths are arranged in parallel between a front chamber portion into which gas flows and a rear chamber portion from which gas is discharged. The flow rate detection means is arranged in one of the flow paths and the measurement flow path, the other gas flow path is formed so that the conductance of the flow path has a predetermined ratio to the conductance of the measurement flow path, A flow path blocking mechanism capable of separately blocking the plurality of gas flow paths is provided at an inlet of each gas flow path, and the flow rate of the measurement flow is determined under a predetermined condition regarding a flow rate of the gas flowing through the measurement flow path. The gas meter according to any one of claims 1 to 3, wherein a flow path blocking mechanism provided in a gas flow path other than the road is configured to be capable of opening and closing.