JP2001159549A - Conduit changeover type gas meter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase a flow rate measurement range with a simple structure without impairing measurement precision on the small flow rate side, in a gas meter having a measurement conduit disposed with a flow rate detection means detecting a gas flow rate. SOLUTION: This gas meter is provided with plural gas conduits 2, while one of the gas conduits 2 is disposed with the flow rate detection means 7 and is set as the measurement conduit 3. The other gas conduits 2 are configured such that a ratio of conductance of the conduits 2 to conductance of the measurement conduit 3 is a prescribed value. Each the gas conduit 2 is provided with a conduit shutoff mechanism 5 capable of shutting off the gas conduit 2. The gas meter is provided with a shutoff control means 9 capable of opening and closing the conduit shutoff mechanisms 5 provided in the gas conduits 2 except the measurement conduit 3 under a prescribed condition concerning the flow rate of a gas passing the measurement conduit 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas meter having a measurement flow path in which a flow rate detecting means for detecting a gas flow rate is provided, a bypass path for the measurement flow path is provided, and the flow to the bypass path is switched. The present invention relates to a flow path switching type gas meter in which a measurable flow rate range of a gas meter is expanded to a large flow rate side.

[0002]

2. Description of the Related Art Conventionally, in a gas meter, a flow rate detecting means comprising a fluidic element is arranged in a measurement flow path, and the upper limit of the flow rate range measurable by the flow rate detecting means is the upper limit of the flow rate range measurable as it is. Had become. That is, in the configuration of the above-described conventional gas meter, the entire gas flow rate to be measured flows through the flow rate detection means to measure the gas flow rate.

[0003]

However, in the gas meter, the gas meter inlet pressure of the gas supply pipe is set, and the gas meter outlet pressure condition to the downstream gas demand equipment is set. The pressure drop of the gas meter itself is limited. That is, the limit of the pressure loss is set. For example, the gas meter inlet pressure of the gas supplied to the flow rate detecting means is about 938 to 981 Pa
(95 to 100 mmAq), the gas meter outlet pressure of the gas to the gas demand facility is about 706 Pa (72 mmAq).
q). This is to satisfy the static pressure condition of about 981 Pa (100 mmAq) of the gas meter inlet pressure to the gas demand facility. Therefore, the lower limit of the outlet pressure of the gas meter is limited to about 804 Pa (82 mmAq), and the pressure loss of the gas meter is set to about 127 Pa (13 mmAq) in consideration of the pressure loss of the pipeline to the gas demand facility. On the other hand, no matter what type of flow rate detection means is used, there is a lower limit flow rate which is a detection limit on the small flow rate side. In addition, no matter what type of the flow rate detecting means is used, there is a maximum flow rate corresponding to the above-described pressure loss limit on the large flow rate side, and the upper limit flow rate is Exists. Therefore, it is difficult to expand the flow rate measurement range by a single flow rate detection means. For example, the lower oscillation limit of a fluidic element for a relatively large flow rate region is about 100 liter / h when the maximum flow rate is 4000 liter / h. Therefore, when adopting this element, in order to complement the small flow side of the flow meter set to the large flow side, for example, a flow sensor using a hot wire anemometer, or a smaller fluidic element, It is provided in series with the corresponding main fluidic element and measures a small flow rate range. However, in this configuration, there is room for improvement in the measurement method on the small flow rate side and the accuracy assurance thereof.

An object of the present invention is to increase the ratio of the minimum flow rate to the maximum flow rate in the flow rate measurement range of the gas meter (for example, to 1: 160) while adopting a simple configuration employing a single flow rate detecting means. , Small flow rate measurement accuracy (eg ±
Another object of the present invention is to provide a gas meter having a wider flow rate measurement range than before without impairing the gas meter (within 3%).

[0005]

[Means for Solving the Problems]

[Characteristic Configuration of the Present Invention] A flow-switching gas meter according to the present invention is characterized in that while a single flow detecting means measures a flow rate, a gas flows through the flow detecting means at a predetermined distribution ratio. , And each of them has the following features.

[0007] A first characteristic configuration of the flow-path switching type gas meter according to the present invention according to claim 1 is that a plurality of gas flow paths are formed and one of the plurality of gas flow paths is formed. The flow rate detecting means is disposed in the measurement flow path, and another gas flow path is formed so that the conductance of the flow path has a predetermined ratio with respect to the conductance of the measurement flow path, and the gas flow path is shut off. A possible flow path blocking mechanism is provided in each gas flow path, and a flow path provided in a gas flow path other than the measurement flow path under a predetermined condition regarding a flow rate of the gas flowing through the measurement flow path. The present invention is characterized in that a blocking control means configured to open and close the road blocking mechanism is provided.

[0008] A second characteristic configuration of the flow path switching type gas meter according to the present invention according to the second aspect is that, in the first characteristic configuration, a measurement state in which a flow path blocking mechanism provided other than the measurement flow path is closed. The primary flow mode is set, and the selected flow path shutoff mechanism is provided in a measurement state in which the flow path shutoff mechanism provided in the other gas flow path is selectively opened while maintaining the flow path in the measurement flow path. Nth order measurement mode (n is a natural number of 2 or more) in ascending order of the total conductance of the entire flow channel
The point is that the lower limit of the flow rate detection of the flow rate detecting means in the n-th measurement mode is set lower than the upper limit of the flow rate detection of the flow rate detecting means in the n-1 order measurement mode. Here, the primary measurement mode is a flow rate measurement mode in which only the measurement flow path is in a flow state, and the secondary measurement mode is a flow state in which all gas flow paths are in a flow state when there are only two flow paths. In the flow measurement mode, when the gas flow path is three or more flow paths, the flow rate in which the gas flow path having the smallest conductance is selected from among the gas flow paths other than the measurement flow path to be in a flow state. It is a measurement mode.

In a third aspect of the present invention, there is provided a gas flow path switching type gas meter according to the second aspect, wherein the gas flow path in which the flow path shut-off mechanism in the n-order measurement mode is open. The point is that the total conductance is configured to be an integral multiple of the conductance of the measurement flow path.

[0010] The fourth characteristic configuration of the flow path switching gas meter according to the present invention described in claim 4 is an integer multiple of the conductance in the third construction, in that (K-natural number) 2 ^K times are as .

According to a fifth aspect of the present invention, there is provided a flow path switching type gas meter according to the present invention, wherein the conductance in the third aspect is an integral multiple of 5 or 10 times, or 5 and 10 times. On the point.

The sixth characteristic configuration of the flow path switching type gas meter according to the present invention according to claim 6 is the third characteristic configuration to the fifth characteristic configuration.
In any one of the characteristic configurations, the flow rate counter for integrating the flow rate from the weighing signal from the flow rate detecting means is provided by the number of measurement modes, and the first flow counter corresponding to the primary measurement mode includes the flow rate counter. The measured weight value of the detecting means is directly integrated as the measured flow value, and the n-th flow counter corresponding to another measurement mode has a value obtained by dividing the total conductance of the gas flow path in the measurement mode by the conductance of the measurement flow path. In that it is configured to integrate the measured weighed value multiplied by.

According to a seventh aspect of the present invention, there is provided a flow path switching type gas meter according to the present invention.
In any one of the characteristic configurations, an outlet flow path from the gas flow path is provided with an outlet pressure detecting means for detecting the outlet flow path pressure, and the outlet flow pressure detected by the outlet pressure detecting means is shut off. The point is that the shutoff control means is configured in addition to the opening and closing operation conditions of the mechanism.

According to an eighth aspect of the present invention, there is provided a flow switching gas meter according to the present invention, wherein the shut-off control means in the sixth characteristic configuration is controlled based on a function preset for the outlet flow pressure. The point is that it is configured to determine the opening / closing operation.

According to a ninth aspect of the present invention, there is provided a flow path switching type gas meter according to the present invention, wherein the shutoff control means in the seventh aspect of the present invention comprises:
The present invention is characterized in that, when the outlet flow pressure detected by the outlet pressure detecting means becomes equal to or lower than the lower limit pressure, the flow passage shutoff mechanism is opened.

According to a tenth aspect of the present invention, there is provided a flow switching gas meter according to a tenth aspect, wherein
The shut-off control means according to any one of the ninth features is configured to determine the open / close operation after a preset delay time when opening / closing the flow path shut-off mechanism.

According to the above-mentioned flow switching gas meter according to the present invention, the gas flows to the flow rate detecting means at a predetermined distribution ratio with respect to the gas flow rate at which the flow rate is measured. The gas flow rate detected by the flow rate detection means can be measured, and each of them has the following unique effects.

According to the first characteristic configuration of the flow path switching type gas meter according to the present invention, the flow rate detected by the flow rate detecting means arranged in the measurement flow path is converted into the total gas flow rate based on the distribution ratio between the gas flow paths. Since the conversion can be performed, the gas flow rate exceeding the detection upper limit flow rate of the flow rate detection means can be measured, and the flow rate measurement lower limit flow rate can be increased, so that the flow rate measurement accuracy can be maintained high. That is, by arranging the flow rate detection means in the measurement flow path so that the conductance of the other gas flow paths has a predetermined ratio with respect to the conductance of the measurement flow path, When the gas flows at the same time, the gas flows through each gas flow path at the predetermined ratio. Therefore, by providing a channel cutoff mechanism at, for example, the inlet of each gas channel, and opening and closing the channel cutoff mechanism by the cutoff control means, the gas amount having a predetermined distribution ratio of the gas amount flowing through the gas meter can be obtained. Is detected, the total gas flow can 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 the present application, the conductance of the gas flow path indicates the ease of fluid flow in the gas flow path (the reciprocal of resistance), and by setting the conductance ratio of the gas flow paths, The distribution ratio of the amount of gas flowing into the gas flow path is determined.

According to the second characteristic configuration of the flow path switching type gas meter according to the present invention, an overlapping area is provided between the flow rate measurement ranges in each measurement mode while the operation and effect of the first characteristic configuration are exhibited. Thus, the number of times of opening and closing of the flow path cutoff mechanism can be reduced, the power consumption is reduced by greatly reducing the frequency of opening and closing of the flow path cutoff mechanism, the cost is reduced by reducing the capacity of the operating power supply, and the gas meter Can function stably. Further, it is easy to correct the transient measurement data when the gas flow path is switched by opening and closing the flow path blocking mechanism. If there is no overlap area, when disturbance due to gas flow path switching occurs, after switching the gas flow path, the detection data in the measurement mode before switching deviates from the flow rate detection range and extrapolation correction is difficult. However, since the overlap area is provided as described above, even if the detection data in the measurement mode before the switching is extrapolated and corrected, the detection data is within the flow rate detection range of the flow rate detecting means, and the extrapolation correction becomes easy. It is.

According to the third aspect of the flow switching gas meter according to the present invention, while exhibiting the function and effect of the second aspect, the detection data from the flow rate detecting means at the time of switching the measurement mode is obtained. Conversion can be performed at high speed.
That is, if the ratio of the conductance of all the channels is an integer between the measurement modes after the switching of the channels, the ratio can be converted by an integer operation, so that a high-speed operation is possible. In addition, power consumption for that purpose can be reduced. For example, a counter that integrates the flow rate for each gas flow path is provided, and multiplied by the ratio of the conductance of the bypass flow path to the conductance of the measurement flow path, and integrated in each counter. Is obtained by calculating the sum of the integrated values of the counters corresponding to the above. As a simple method, a predetermined number of pulses are inserted and generated for each pulse of the output signal from the flow rate detecting means using a burst signal generator or the like, triggered by the up edge or the down edge of each pulse. I just need to.

According to the fourth characteristic configuration of the flow path switching type gas meter according to the present invention, the flow rate can be converted at a higher speed while exhibiting the operation and effect of the third characteristic configuration. In other words, when storing the flow rate detection data from the flow rate detection means into a binary number register of the arithmetic unit, if by the ratio of conductance and 2 ^K, it can be converted by simply shift operations depending data to the value of K . Therefore, the operation device can be simplified, and the main operation circuit can be constituted only by the shift register and the adder. As a result, the power consumption for the operation can be further reduced.

According to the fifth aspect of the flow switching gas meter according to the present invention, the flow rate can be converted at a higher speed while exhibiting the function and effect of the third aspect. That is, when the flow rate detection data from the flow rate detection means is integrated in the BCD counter of the arithmetic unit, if the conductance ratio is 5 or 10 times or 5 and 10 times, the data is directly input to the BCD counter. It can be converted only by: For example, if the conductance ratio is set to 5 times, a pulse may be directly input to the 5th digit of the BCD counter. If the conductance ratio is set to 10 times, the pulse is input to the upper digit counter. You just have to enter it directly. Alternatively, a predetermined number of additional pulses (4 or 9 pulses) may be inserted and transmitted as a burst signal for each pulse as an oscillation signal from the flow rate detecting means. Therefore, the arithmetic unit can be simplified, and the main arithmetic circuit can be constituted only by the adder. As a result, the power consumption for the operation can be further reduced.

According to the sixth aspect of the flow switching gas meter according to the present invention, the flow counter corresponding to each measurement mode can be obtained while exhibiting any of the effects of the third to fifth aspects. Are provided, and for each measurement mode,
By directly integrating the measured weights multiplied by the correction coefficient based on the ratio of the conductance to the measured weight in the primary measurement mode, when the n-th measurement mode is selected,
The measured flow value can be read directly from the n-th flow counter corresponding to the n-th measurement mode. Therefore, it is not necessary to change the correction coefficient or perform the correction calculation in accordance with the switching of the gas flow path, so that the calculation load can be reduced, the power consumption can be reduced, and the calculation speed can be improved. In particular, with the fourth characteristic configuration, the n-th flow counter corresponding to the n-th measurement mode shifts the data by a digit from the (n-1) -th flow counter corresponding to the (n-1) -th measurement mode, and stores the data. Only the shift is required, and the operation speed and the power consumption required for the operation can be extremely reduced.

According to the seventh aspect of the flow switching gas meter according to the present invention, the gas supply pressure to the downstream side is obtained while exhibiting any of the effects of the first to sixth aspects. It is also possible to expand the flow rate detection range of the flow rate detection means toward the large flow rate while stabilizing the flow rate. That is,
By setting the opening / closing operation condition of the flow path blocking mechanism by the blocking control means, as well as the preset maximum detected flow rate, the outlet flow path pressure detected by the outlet pressure detection means as the opening / closing operation condition,
When switching the gas flow path, it is possible to prevent the outlet flow path pressure from becoming too low, and if there is a margin in the outlet flow path pressure at the maximum detected flow rate, the flow path switching can be delayed. Thus, the detected flow rate can be expanded to the large flow rate side. For example, a flow rate detection limit is set in consideration of a decrease in the linearity of the measured flow rate in the gas meter on the large flow rate side, and a minimum pressure is set for the outlet flow path pressure, and the detected flow rate is equal to or greater than the flow rate detection limit. Or when the outlet channel pressure becomes equal to or lower than the minimum pressure, the gas channel is switched to the higher-order measurement mode. By doing so, the pressure loss of the flow rate detecting means, which has conventionally been a design condition, is not limited to the flow rate detection upper limit set at about 127 Pa (13 mmAq), and the outlet flow path pressure is guaranteed to be equal to or higher than a predetermined pressure. Meanwhile, the flow rate detection range can be expanded to the large flow rate side. In particular, when the gas meter inlet pressure is high, the gas meter inlet pressure can be reduced to about 1962 without unnecessarily narrowing the flow rate detection range.
With Pa (200 mmAq), the flow rate detection limit can be surely expanded to twice the flow rate detection upper limit. Therefore, in a gas meter having a gas flow path in addition to the measurement flow path and having an n-order measurement mode, it is possible to increase the lower limit of the flow rate detection range so as not to erroneously detect acoustic noise. Can be improved.

According to the eighth aspect of the flow switching gas meter according to the present invention, it is possible to cope with high-speed pressure fluctuations while exhibiting the functions and effects of the seventh aspect. That is, with respect to the outlet flow path pressure, the term of the outlet flow path pressure at the time of measurement in relation to the gas supply pressure to the downstream side in advance and the decay time are considered in the change speed of the outlet flow path pressure at that time. A function that defines the assumed pressure after the delay time assumed as the sum of the term put in is set, and the cutoff control means is set to a value of this function, that is, the condition that the assumed pressure matches the preset pressure set in advance. If the flow path shutoff mechanism is set to open and close, the effects of time delays such as flow switching, detection of outlet flow pressure, and calculation can be reduced, and even if there is a rapid pressure fluctuation, there is no delay. The switching of the flow path can be performed.

According to the ninth characteristic configuration of the flow switching gas meter according to the present invention, in the operation and effect of the seventh characteristic configuration, the lower limit of the outlet flow pressure is lower than the outlet flow pressure. The outlet flow path pressure is maintained within a predetermined range by adjusting the total conductance of all open gas flow paths so that the outlet flow path pressure does not fall below the lower limit pressure. You can.

According to the tenth characteristic configuration of the flow path switching type gas meter according to the present invention described above, any one of the effects of the first to ninth characteristic configurations can be achieved, and the determination of the flow path switching is disturbed. This makes it possible to prevent erroneous decisions based on the In other words, the change in the normal gas flow rate is a stepwise change, and a transient state for that is detected by the flow rate detection means, but the flow rate data detected by the flow rate detection means determines the gas flow path switching condition. If the condition is satisfied, the flow switching is determined only when the condition is satisfied after a preset delay time. In this way, the gas flow path can be switched in a timely and reliable manner without waiting for the detection flow rate to stabilize and performing a complicated process of judging a change in the detection flow rate. In particular,
When the flow rate detecting means is a fluid vibration type flow meter using a fluidic element, noise generated at the time of switching the flow path is detected as fluid vibration, which is suitable for preventing this from being drawn into the weighing signal as noise. It is. Specifically, the number near the lower limit frequency where sound waves propagate adiabatically
In order to exclude a signal of Hz, the delay time is preferably set to about 1 to 10 seconds.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a flow switching 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, an inlet distributor 1 having a gas introduction section 1a connected to a gas supply pipe and an outlet collecting section 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. At the inlet side of each gas flow path 2, a shutoff valve 5
A, 5B and 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 in each of bypass paths 4A and 4B.
The first orifice 11A provided in 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 if the conductance of the second orifice 11B provided in the conductance setting means 11 provided in the second bypass flow path 4B is set to 15 times. That is, based on the flow path resistance of the fluidic element, the two orifices 11A, 1 provided in the conductance setting means 11 provided in both the bypass flow paths 4A, 4B.
The opening diameter of the 1B orifice nozzle is set.
Thus, the total conductance of the gas passage 2 including the measurement flow path 3 flow path blocking mechanism 5 in order n measurement mode is opened, 2 ^K times the conductance of the measuring channel 3 (K is a natural number) and integer It is configured to be doubled. For example,
The conductance in the primary measurement mode using only the measurement flow path 3 and the shutoff valve 5B provided in the first bypass flow path 4A
Is opened, the total conductance in the secondary measurement mode using the measurement flow path 3 and the first bypass flow path 4A, and the measurement flow path 3 and the second bypass flow path are opened by opening the shutoff valve 5C provided in the second bypass flow path 4B. The ratio is set to 1: 4: 16 with respect to the total conductance of the third measurement mode using 4B.

When the conductance of each measurement mode is set as described above, for example, as shown in FIG. 2, a flow counter 15 for integrating the flow rate from the measurement signal of the flow rate detection means 7 is provided for each measurement mode. And prepare for it. 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 measured value, and this is integrated as a measured measured value in the first flow counter 15A corresponding to the primary measurement mode. It is. 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 as 2 ^K times, as described above, the binary data contained in the first flow counter 15A corresponding to the primary measurement mode, the corresponding secondary measurement mode By simply shifting the digit to the second flow counter 15B and transferring it, the measured flow value in the second measurement mode can be integrated, and the third flow counter 15 corresponding to the third measurement mode can be integrated.
To C, the binary data stored in the second flow counter 15B is shifted and transferred. In other words, the n-th flow counter corresponding to the n-th measurement mode contains the n-1 th flow counter corresponding to the n-th measurement mode.
It is only necessary to transfer the binary data by shifting the digits. 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 to each flow counter in accordance with the corresponding measurement mode. 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 the 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 fluidic element is designed under the conditions that the static pressure of the gas supplied outside the tower is about 981 Pa (100 mmAq) and the pressure loss outside the tower until reaching the gas meter is about 49 Pa (5 mmAq). 10 liter gas flow
When the oscillation frequency with respect to / h is set to 2 Hz and the maximum pressure loss of the flow detection means 7 is set to about 127 Pa (13 mmAq), the flow detection range is 10 to 250 l / h (the oscillation frequency is 2
５０50 Hz). In this case, the opening diameter of the orifice nozzle provided in the first bypass passage 4A is 1.6 mm, and the opening diameter of the orifice nozzle provided in the second bypass passage 4B is 3.
2 mm. With this 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 liter / h, and the first bypass together with the shutoff valve 5A of the measurement flow path 3 is used. Shut-off valve 5B provided in flow path 4A
In the secondary measurement mode in which
The flow rate measurement range is 40 ~ corresponding to the flow rate detection range of liter / h.
1000 liter / h, and the shut-off valve 5
A with the shut-off valve 5C of the second bypass passage 4B opened together with A
In the next measurement mode, the flow measurement range is 160 to 40.
It becomes 00 liter / h. As a result, the flow rate measurement range of the gas meter having the first to third measurement modes is 10 to 4000 liter / 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 is 250 liter / 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. Between 40 liters / h and 40 liters / h of the flow measurement lower limit corresponding to the flow detection lower limit of
There is an overlapping measurement range of, and even between the secondary measurement mode and the tertiary measurement mode, the flow measurement upper limit of 1000 liter / h corresponding to the flow detection upper limit of the flow detection means 7 in the secondary measurement mode and the tertiary measurement An overlap measurement range of 160 to 1000 liter / h exists between the lower limit of the flow rate measurement of 160 liter / h corresponding to the lower limit of the flow rate detection of the flow rate detecting means 7 in the mode. 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 mode sequentially shifts to the measurement mode having a large total conductance as the flow rate increases, and sequentially shifts to the measurement mode with a small total conductance as the flow rate decreases. .

Further, in the above-described configuration, an outlet pressure detecting device capable of detecting an outlet channel pressure as a gas meter outlet pressure for supplying a gas to a downstream side at an outlet collecting portion 6 corresponding to an 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 lower limit of flow rate detection of the flow rate detecting means 7. When it is detected that the lower limit of flow rate measurement 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 liters / h in the above example) is detected in the third measurement mode, at the same time as closing the shutoff valve 5C provided in the second bypass flow path 4B,
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 becomes 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 shutoff valve 5B provided in the first bypass flow path 4A is closed and flow is stopped. The route 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 channel pressure drops to about 294 Pa (30 mmAq) or less, all the channel shut-off mechanisms 5, ie, the measurement channel 3
Valve 5A provided on the bypass passage 4
B and 5C are all 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, the switching of the flow path to the higher-order measurement mode is performed based on the outlet flow pressure, so that the line formation for the flow rate on the large flow rate side of the measurement signal 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 inlet pressure of the gas meter is increased, a margin is given to the pressure loss, which is a 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 become lower than the lower limit pressure, for example, when a weighing signal of 2 to 50 Hz is used, if the weighing signal on the large flow rate side has linearity, 2-1 to 2 is used.
Using the metering signal of 00 Hz, the flow rate measurement range of the gas meter can be expanded to 10 to 8000 liter / h. 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. Accordingly, 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 shutoff 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.

It is more preferable that the outlet collecting section 6 is made of a flexible material for the outer wall so that the inner volume has elasticity. When there is a sudden change in the gas usage amount on the downstream side, it is conceivable that the above-described switching of the gas flow path may not be followed, but by changing the volume of the outlet collecting part 6,
Using this as a buffer, the gas supply pressure to the downstream side can be stably maintained.

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 arranged at the inlet of each gas flow path 2 in the inlet distribution section 1. If this is done, the flow distribution to each gas flow path 2 will be accurate, and 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, an example has been described in which the fluid vibration type flow detecting means 7 using a fluidic element is arranged in the measurement flow path 3. However, the present invention is not limited to this, and may be an ultrasonic flow meter, or a conventional film-type gas flow meter.

<2> In the above embodiment, an example was described in which an orifice nozzle for setting the conductance was provided in the bypass flow path 4 other than the measurement flow path 3 in the gas flow path 2. The conductance of each of the bypass passages 4 may be set without providing an orifice nozzle. For example, the conductance of the conduit may be set by setting the conduit length together with the conduit diameter. Alternatively, the orifice nozzle arranged in the bypass flow path 4 may be formed by an orifice having a variable opening diameter, and the conductance of the flow path may be changed by changing the opening diameter. Further, the bypass passage 4 may be configured such that orifice nozzles having a plurality of opening diameters can be exchanged inside. In these cases, a single bypass flow path 4 is provided so that the gas flow path 2 can be configured as two flow paths. As an example of the latter, a plurality of gate valves are provided in the bypass flow path 4,
Examples include those in which each valve element is provided with an orifice nozzle, those having a similar configuration, and those in which a turret having an orifice nozzle is disposed in the bypass flow path 4.

<3> In the above embodiment, an example was described in which the bypass flow path 4 was formed by two flow paths, the first bypass flow path 4A and the second bypass flow path 4B. However, the present invention is not limited to this, and may be a single bypass flow path, or may be provided with three or more bypass flow paths.

<4> In the above embodiment, each
An orifice nozzle is provided in each of the bypass passages 4A and 4B.
And the conductance of each of the
The first bypass passage 4A is three times as large as the
If the path 4B is set to be 15 times, the nth order measurement can be performed.
Measurement flow with the flow path cutoff mechanism 5 open in the constant mode
The total conductance of the gas flow path 2 including the path 3 is
Road 3 conductance 2 ^K It ’s twice as convenient
As described above, the conductor of the first bypass passage 4A
Equal to the conductance of the measurement flow path 3, and
The conductance of the path flow path 4B is changed to the conductance of the measurement flow path 3
It may be twice as close. With this configuration
For example, the total conductor of the gas flow path 2 including the measurement flow path 3
Is the conductance of the measurement channel 3^K Double
Is satisfied in the second measurement mode.
By using the path 3 and the first bypass flow path 4A,
The total conductance is twice the conductance of the measurement channel 3
In the third measurement mode, all the gas flow paths 2 are used.
The total conductance of the measurement flow path 3
The flow rate measurement range as a whole can be four times the distance
Has a similar effect. In addition, this total
Conversion is easy even if the multiplication of the conductance is an integer.
This is useful because it reduces the computational load on the measurement circuit.
When configured as a gas meter, this total
Rangeability even if the duty factor is not an integer
It is very useful in that it can be increased.

<5> In the above embodiment, the measurement mode is defined as a primary measurement mode using only the measurement flow path 3,
The secondary measurement mode using the measurement flow path 3 and the first bypass flow path 4A by opening the shutoff valve 5B provided in the first bypass flow path 4A, and the measurement flow by opening the cutoff valve 5C provided in the second bypass flow path 4B Although an example has been described in which the measurement mode is configured in three types of measurement states, that is, the third measurement mode using the path 3 and the second bypass flow path 4B, the measurement mode may be configured by adding a state in which a plurality of bypass flow paths 4 are simultaneously used. Good. In the above example, a fourth measurement mode using the first bypass channel 4A and the second bypass channel 4B simultaneously may be added. The same applies to the case where three or more bypass flow paths 4 are provided.
As described above, when a plurality of gas flow paths 2 are used at the same time, when the flow path cut-off mechanism 5 is temporarily closed and then opened, the gas flow having a small conductance in the gas flow path 2 is used. It is preferable to open the flow path blocking mechanism 5 sequentially from the path 2. In the above example, the shutoff valve 6A is opened first. Next, when the shutoff valves 6B and 6C are opened, the shutoff valve 6B is opened first.
By doing so, the shut-off valve 6A functions as a sub-valve of the shut-off valve 6B, and the shut-off valve 6C functions as a sub-valve of the shut-off valve 6B, so that the valve opening load of the shut-off valve due to fluid pressure can be reduced. It is.

<6> In the above-described embodiment, if the determination regarding the switching of the flow path by the cut-off control means 9 is performed with a delay provided with a delay time, the flow path blocking mechanism at the time of switching the flow path is provided. Although it has been described that the disturbance caused by the generation of the sound wave due to the opening and closing of the valve 5 can be excluded from the determination, the flow measurement upper limit of the gas meter can be extended to the large flow side by the configuration having the bypass flow path 4 described above. Even if the lower limit of the flow rate detection of 7 is raised and the oscillation frequency at the lower limit of the flow rate detection is raised to 10 Hz, the effect of noise removal is similarly obtained.

<7> In the above embodiment, the stationary pressure of the gas supplied outside the tower is set to about 981 Pa (100 mmAq),
The pressure loss outside the column up to the detection means 7 is about 49 Pa (5
Under the design conditions of mmAq), the oscillation frequency at the lower detection flow rate of the fluidic element as the detection means 7 is 2 Hz, and the maximum pressure loss is about 127 Pa (13 mm).
The example in which the flow rate detection range is defined as Aq) has been described, but the supply pressure of the gas is increased and the static pressure of the supply gas outside the column is about 1765 to 1962 Pa (180 to 200 mmAq).
In this case, in order to satisfy that the gas meter outlet pressure from the gas meter is guaranteed to be about 981 Pa (100 mmAq) or more, instead of the outlet channel pressure determined by the conventional design conditions, the outlet The pressure may be set, and the flow rate detection range of the flow rate detection means 7 may be determined by the outlet flow path pressure.

That is, if the static pressure of the gas supplied outside the column is about 1
Assuming that the pressure is 765 Pa (180 mmAq), in order to maintain the guaranteed pressure of the outlet channel pressure at about 981 Pa (100 mmAq), the pressure loss of the gas meter is about 4% of the pressure loss outside the column.
Taking into account 9 Pa (5 mmAq), about 735 Pa (7
5mmAq). Therefore, the outlet flow pressure detected by the outlet pressure detecting means 8 provided in the outlet collecting part 6 is compared with the minimum pressure, and the flow at which the outlet flow pressure reaches the minimum pressure is determined as the flow detection limit on the large flow side. That is. If this flow rate detection limit is twice as high as the conventional flow rate detection upper limit, the pressure loss of the flow rate detection means becomes four times, and 510 Pa
(52 mmAq), the outlet channel pressure is about 1206
Pa (123 mmAq) and the minimum pressure is about 1177
Even at Pa (120 mmAq), a sufficient margin can be provided for the gas meter outlet pressure. As a design condition of the gas meter, the minimum pressure is set to about 1275 Pa (130 mm).
Aq). In this case, when the fluidic element is used as the flow rate detecting means 7, the flow path switching condition to the higher-order measurement mode is set by setting the upper limit frequency of the oscillation frequency of the fluidic element to 100 in addition to the minimum pressure.
Hz, the outlet flow pressure is below the minimum pressure,
What is necessary is just to let the oscillation frequency of the fluidic element reach the upper limit frequency. Even if the flow rate detection limit is three times the upper limit of the flow rate detection, the oscillation of the fluidic element maintains the linearity. It is desirable to limit the limit to about 2.5 times the upper limit of the flow rate detection. In this case, for example, the minimum pressure is about 1177 to 981 Pa (120 to 100 mmAq),
The upper limit frequency may be 125 Hz.

<8> In the above embodiment, when the detected flow rate of the flow rate detecting means 7 reaches the lower detection limit, the mode shifts to the lower-order side measurement mode, but as described in <7> above. When the flow rate detection range is extended to the large flow rate side, for example, if about 1275 Pa (130 mmAq) is set as the flow rate detection limit of the flow rate detection means 7, for example, between 40 and about 40 seconds between the secondary measurement mode and the primary measurement mode. Since there is an overlapping measurement area of 500 liter / h, a sufficient overlapping measurement area can be secured even if the flow rate detection lower limit is raised to the large flow rate side. By the way, since a disturbance frequency of about 4 Hz generated as acoustic noise is included in the conventional flow rate detection range, when a fluidic element is used as the flow rate detection means 7, this disturbance frequency region is set outside the oscillation frequency range. Is desirable. Therefore, as a condition for shifting to the lower-order measurement mode, a lower limit frequency is provided for the oscillation frequency of the fluidic element instead of the conventional lower detection limit flow rate, and the flow path switching is performed when the detection frequency becomes equal to or lower than the lower limit frequency. It is desirable to do so. Therefore, for example, if the lower limit frequency is 6
If it is Hz, it will not be affected by the acoustic noise,
In the example described in the above <7>, the flow rate when switching from the secondary measurement mode to the primary measurement mode is 1
It will be 20 liters / h. Therefore, between the secondary measurement mode and the primary measurement mode, it is still 120 to 500 liter / h.
The overlapping measurement area can be secured. In order to further avoid the influence of acoustic noise, the lower limit frequency is set to 8 Hz, and
The lower limit of the flow rate measurement in the next measurement mode is 120 liters / h, and the lower limit of the flow rate measurement in the third measurement mode is 480 liters.
Even with / h, a sufficient overlapping measurement area can be secured between each measurement mode.

<9> In the above <8>, in a normal use state of the gas meter, the outlet flow pressure detected by the outlet pressure detecting means 8 becomes equal to or lower than the reference pressure (for example, when the outlet flow pressure is 98 .1 Pa (10 mmAq) or less) is detected three times or more in one day, the frequency of gas flow switching can be reduced by changing the lower limit frequency to 4 Hz or less. Further, when the state in which the lower limit frequency is operated at less than 6 Hz continues for 30 seconds, it is desirable to temporarily switch the measurement mode to a low order and confirm that there is no influence of disturbance such as acoustic noise. In this case, when it is confirmed that the influence of the disturbance has been received, the time and the frequency of the disturbance are stored, and the lower limit frequency may be set to 8 Hz (in the above example, the flow rate in the secondary measurement mode is changed). The lower limit of the flow rate measurement is 160 liters / h while the upper limit of the measurement is 1000 liters / h, and the lower limit of the flow rate measurement is 640 liters / h in the third measurement mode while the upper limit of the flow rate measurement is 4000 liters / h. Become.).

<10> In the above description, an example in which the flow path switching condition is set to a specific condition has been described. However, in addition to the outlet flow pressure, the change rate of the outlet flow pressure and its decay time May be set, and the shutoff control mechanism 9 may be configured to switch the flow path when the value of the function reaches a preset value. For example, the cutoff control mechanism 9 may be configured so that the function is set to represent an assumed pressure after a delay time and the gas flow path is switched when the assumed pressure reaches a preset set pressure. it can. Pm is the outlet flow path pressure detected by the outlet pressure detecting means 8 at the measurement time (t ₀ ), and t
_{Let d be} the decay time of the outlet flow path pressure, and Δt be the delay time indicating an assumed time delay, and the outlet flow path pressure (Pm)
The change speed of the outlet flow pressure (Pm) at the measurement time (t ₀ ), the decay time (t _d ), and the delay time (Δt) are assumed after the delay time (Δt). As a function representing the assumed pressure (Pc), for example,

[0055]

(Equation 1)

As described above, it is possible to define the amount of pressure change that predicts the pressure change up to the delay time as an assumed pressure added to the outlet flow path pressure at the measurement time. In this way, the predicted pressure is defined as a function as an assumed pressure, and by providing a set pressure for the assumed pressure, even if there is a time delay element,
It is possible to prevent a delay in control response.

[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.

[Explanation of symbols]

 2 Gas flow path 3 Measurement flow path 5 Flow path shut-off mechanism 7 Flow rate detection means 8 Outlet pressure detection means 9 Shut-off control means 15 Flow counter

(72) Inventor Hiroshi Matsushita 4-1-2 Hirano-cho, Chuo-ku, Osaka-shi, Osaka Prefecture Inside Osaka Gas Co., Ltd. (72) Inventor Shuichi Okada 4-1-2, Hirano-cho, Chuo-ku, Osaka-shi, Osaka No. Osaka Gas Co., Ltd. F-term (reference) 2F030 CC13 CD13 CE02 CF05 CF09

Claims (10)

[Claims] 1. A gas meter having a measurement flow path in which a flow rate detecting means for detecting a gas flow rate is arranged, wherein the gas meter is formed by forming a plurality of gas flow paths and one of the plurality of gas flow paths. And the other gas flow path is formed so that the conductance of the flow path has a predetermined ratio with respect to the conductance of the measurement flow path. A flow path blocking mechanism capable of blocking a path is provided in each gas flow path, and is provided in a gas flow path other than the measurement flow path under a predetermined condition regarding a flow rate of a gas flowing through the measurement flow path. A flow switching gas meter provided with a cutoff control means configured to open and close a flow cutoff mechanism. 2. A measurement state in which a flow path blocking mechanism provided other than the measurement flow path is closed is set as a primary measurement mode, and the measurement flow path is provided in the other gas flow path while maintaining the flow state. The measurement state in which the flow path blocking mechanism is selectively opened is changed to an n-th measurement mode (n is 2) in ascending order of the total conductance of the entire flow path in which the selected flow path blocking mechanism is provided.
2. The flow rate according to claim 1, wherein the flow rate detection lower limit of the flow rate detection means in the n-th measurement mode is set to be lower than the flow rate detection upper limit of the flow rate detection means in the (n−1) -order measurement mode. Road switching type gas meter. 3. The apparatus according to claim 2, wherein the total conductance of the gas flow path in which the flow path blocking mechanism is opened in the n-th measurement mode is an integral multiple of the conductance of the measurement flow path. Flow path switching type gas meter. 4. The gas meter according to claim 3, wherein the integral multiple is 2 ^K times (K is a natural number). 5. The flow-switching gas meter according to claim 3, wherein the integral multiple is 5 times, 10 times, or 5 times and 10 times. 6. A counter for integrating a flow rate from a weighing signal from the flow rate detecting means by the number of the measurement modes is provided, and a first flow rate counter corresponding to the primary measurement mode is provided with a counter of the flow rate detecting means. The detected weighed value is directly integrated, and the n-th flow counter corresponding to another measurement mode has a measured weighed value multiplied by a value obtained by dividing the total conductance of the gas flow path in the measurement mode by the conductance of the measurement flow path. 6. The method according to claim 3, wherein the integration is performed.
Item 7. A flow path switching type gas meter according to Item 1. 7. An outlet flow path from said gas flow path is provided with an outlet pressure detecting means for detecting an outlet flow path pressure, and said outlet flow pressure detected by said outlet pressure detecting means is cut off by said flow path shut-off. 7. The gas meter according to claim 1, wherein the shut-off control means is configured in addition to the opening and closing operation conditions of the mechanism. 8. The flow-switching gas meter according to claim 7, wherein said shut-off control means is configured to determine said opening / closing operation based on a function preset for said outlet flow pressure. 9. A lower limit pressure is set for the outlet flow path pressure,
The flow path according to claim 7, wherein the shutoff control means is configured to open the flow path shutoff mechanism when the outlet flow path pressure detected by the outlet pressure detection means becomes equal to or lower than the lower limit pressure. Switchable gas meter. 10. The shut-off control means is configured to make a judgment on the shut-off operation after a preset delay time when the shut-off operation of the flow path shut-off mechanism is performed.
10. The flow-path switching gas meter according to any one of claims 9 to 9.