JP3508993B2 - Flow rate measuring method and apparatus and electronic gas meter - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow rate measuring method and apparatus for measuring the flow rate of a fluid such as gas, and an electronic gas meter for integrating and displaying the flow rate of gas measured by the method and apparatus. A flow rate measuring method and apparatus for measuring the flow rate by intermittently measuring the flow velocity of the fluid in the flow channel and estimating that the fluid has flowed through the flow channel of a predetermined cross section for the intermittent time at the measured flow velocity, and an electronic gas meter It is about.

[0002]

2. Description of the Related Art Conventionally, as a flow rate measuring method and apparatus of this type, for example, an ultrasonic flow rate measuring apparatus using an ultrasonic sensor disclosed in Japanese Patent Publication No. 7-119638 and Japanese Patent Publication No. 6-43906. There is a thermal type flow rate measuring device using a thermal type sensor disclosed in the publication.

The ultrasonic type flow rate measuring device uses a flow rate sensor as a flow rate detecting means by means of two acoustic transducers composed of, for example, piezoelectric vibrators, which operate at ultrasonic frequencies arranged at a fixed distance in the gas flow path. A physical quantity consisting of the time in which the ultrasonic signal is propagated between the transducers in the gas flow direction and in the direction opposite to the gas flow direction by alternately performing the operation of receiving the ultrasonic signal generated by one transducer to the other transducer. Is measured intermittently, the flow velocity of the gas flowing in the gas flow passage is intermittently obtained based on the two measured propagation times, and the instantaneous flow rate is calculated by multiplying this flow velocity by the cross-sectional area of the gas flow passage. The calculated flow rate is calculated. The instantaneous flow rate is multiplied by the intermittent time to obtain the passing flow rate, and the integrated flow rate obtained by integrating the passing flow rate is displayed. By Rukoto may configure the electronic gas meter.

The thermal type flow rate measuring device utilizes the fact that the heat generated by the heater is transferred in the upstream and downstream directions depending on the magnitude of the flow velocity, and the temperature detected intermittently by the temperature sensor provided in the upstream and downstream of the heater. The flow velocity is indirectly measured by a physical quantity consisting of the difference.

Although any of the devices intermittently drives the flow rate sensor as the flow rate detecting means, it requires a relatively large amount of power consumption. Therefore, for the purpose of increasing the flow rate detection accuracy while suppressing the power consumption, the measurement interval performed by driving the sensor is short when the flow rate fluctuation is large, and the measurement interval is long when the flow rate fluctuation is small, and the flow velocity is adjusted according to this measurement interval. Intermittent time measured intermittently,
That is, changing the sampling time is performed, for example, in Japanese Patent Laid-Open Nos. 9-21667 and 10-82670.
It is proposed in the publication.

[0006]

In the above-mentioned proposed flow rate measuring method and apparatus, when the measurement interval is the longest,
As shown in FIG. 8A, if the gas is used immediately after sampling, there is no opportunity to measure until the next sampling, and the flow rate during the period substantially corresponding to the sampling interval indicated by diagonal lines is not integrated. It will be. It can be seen that such a state includes a large error in the integrated value based on the measured flow rate, as is clear from comparison with the case where gas is used immediately before sampling as shown in FIG. 8B. Therefore, even if the fluctuation of the flow rate is small, the measurement interval performed by driving the sensor cannot be extremely lengthened. That is, in the conventional flow rate measuring method and device,
If the sampling interval is lengthened, the measured flow rate will be multiplied by the sampling interval to obtain the sum, and for example, an error will occur in the amount of gas used.Therefore, the measurement interval cannot be made extremely large. There was a limit to the reduction of.

Therefore, in view of the above-mentioned conventional problems, the present invention makes it possible to make the flow rate measurement interval extremely long without degrading the flow rate measurement accuracy and further reduce the power consumption. And to provide a device.

In view of the above-mentioned situation, the present invention also makes it possible to extremely lengthen the flow rate measurement interval without lowering the flow rate measurement accuracy and to further reduce the power consumption, but to reduce the passing flow rate. An object of the present invention is to provide an electronic gas meter capable of reducing the error and accurately displaying the gas usage amount.

[0009]

In order to solve the above-mentioned problems, the present invention as set forth in claim 1, wherein the pressure in the flow path for flowing the fluid is constantly and intermittently monitored, and the first pressure is predetermined. Of the physical quantity that changes according to the flow velocity of the fluid when it is stable without exceeding the value of, and corresponds to the measured physical quantity when the pressure changes beyond the first value and becomes unstable. By measuring the flow rate of the fluid that has passed through the flow passage during the period during which the pressure was stable by multiplying the flow velocity, the cross-sectional area of the flow passage, and the time corresponding to the period during which the pressure was stable, When the pressure exceeds the first value and is not stable, the physical quantity that changes according to the flow velocity of the fluid is intermittently measured, and during the period when the pressure is not stable, the intermittent measurement is performed. The measured physical quantity and the cross-sectional area of the flow path and the It consists in the flow rate measuring method characterized by measuring the flow rate through the fluid passing through the flow path by multiplying the time corresponding to the missing gap.

In the flow rate measuring method according to claim 1,
When the pressure in the flow path where the fluid flows is stable, the physical quantity that changes according to the flow velocity of the fluid is measured.When the pressure becomes unstable, the flow speed corresponding to the measured physical quantity and the cross-sectional area and pressure of the flow path are stable. Since the flow rate of the fluid that has passed through the flow path during the period when the pressure was stable is measured by multiplying by the time corresponding to the Assuming that the pressure in the flow path is stable due to no flow, the physical quantity is measured only once when the pressure is stable, and the flow rate of the fluid passing during the stable pressure period is accurately measured. be able to.
When the pressure is not stable, the physical quantity that changes according to the flow velocity of the fluid is measured intermittently during that period, and the flow velocity, the cross-sectional area of the flow path, and the intermittent area corresponding to the measured physical quantity are measured intermittently. Since the flow rate of the fluid that has passed through the flow channel is measured by multiplying by the time corresponding to the interval, even if the flow rate of the fluid flowing through the flow channel changes momentarily, The measurement can be performed accurately.

According to a second aspect of the present invention, in the method according to the first aspect, when the pressure changes over a predetermined second value that is larger than the first value, the pressure changes depending on the flow rate of the fluid. The physical quantity that changes by intermittently measuring the physical quantity at intervals shorter than the intermittent interval, the period during which the pressure is changing, the flow velocity corresponding to the measured physical quantity for each intermittent measurement and the cross-sectional area of the flow path. The flow rate measuring method is characterized in that the flow rate of the fluid that has passed through the flow path is measured by multiplying by and the time corresponding to the short intermittent interval.

In the method according to claim 2, claim 1
In addition to the effect of the invention of (1), when the pressure changes significantly, the physical quantity that changes according to the flow velocity of the fluid is intermittently measured at shorter intervals, and is measured at each intermittent measurement during the period when the pressure is changing. Since the flow rate of the fluid passing through the flow path is measured by multiplying the flow velocity corresponding to the physical quantity, the cross-sectional area of the flow path, and the time corresponding to a short intermittent interval, the flow rate of the fluid passing through the flow path is measured. Even if there is, the measurement interval of the physical quantity is shortened and the passing flow rate can be accurately measured.

According to a third aspect of the present invention, in the method according to the first or second aspect, the pressure monitoring interval is a random time within a predetermined range and an average value of which corresponds to the intermittent interval. There is a flow rate measuring method characterized in that it is performed at intervals of.

In the method according to claim 3, claim 1
Alternatively, in addition to the function of the invention described in 2, since the pressure monitoring is performed at random time intervals, even if a pulsating flow is generated, it is possible to prevent the pressure change from being detected in synchronization with the pulsating flow. .

According to a fourth aspect of the present invention, as shown in the basic configuration diagram of FIG. 1, a measuring means 1 for measuring a physical quantity that changes according to the flow velocity of the fluid in the flow channel 10, and a pressure in the flow channel. And the pressure in the flow path detected by the pressure detecting means are constantly and intermittently monitored, and it is confirmed that the pressure does not change beyond a predetermined first value and is stable. The first pressure detecting means 14a-1 for detecting, and the first pressure detecting means 14a-1
When the pressure detecting means detects the stability of the pressure, the measuring means measures the physical quantity that changes according to the flow velocity of the fluid, and when the first pressure detecting means stops detecting the stability of the pressure, Passage of the fluid that has passed through the flow channel during the period when the pressure was stable by multiplying the flow velocity corresponding to the measured physical quantity, the cross-sectional area of the flow channel, and the time corresponding to the period when the pressure was stable. First to measure the flow rate
When the passage pressure measuring unit 14a-2 and the first pressure detecting unit stop detecting pressure stability, the measuring unit is caused to intermittently measure a physical quantity that changes according to the flow velocity of the fluid, and During the period when the pressure is not stable, the fluid that has passed through the flow channel by multiplying the flow velocity corresponding to the measured physical quantity for each intermittent measurement, the cross-sectional area of the flow channel, and the time corresponding to the intermittent interval. The second flow rate measuring means 14a-3 for measuring the flow rate of the second flow rate is included in the flow rate measuring device.

In the apparatus according to the fourth aspect, the first pressure detecting means 14a-1 constantly and intermittently monitors the pressure in the flow path 10 detected by the pressure detecting means 16, and the first pressure is predetermined. When the first passage flow rate measuring means 14a-2 detects that the flow rate is stable without changing beyond the value of, the measuring means 1 causes the measuring means 1 to measure a physical quantity that changes according to the flow velocity of the fluid,
When the first pressure detection means no longer detects pressure stability, the pressure is stabilized by multiplying the flow velocity corresponding to the measured physical quantity, the cross-sectional area of the flow path, and the time corresponding to the period during which the pressure is stable. Since the flow rate of the fluid that has passed through the flow path is measured during the period when the flow is flowing, the pressure in the flow path is considered to be stable when the fluid is flowing in the flow path. When the pressure is stable, the physical flow rate can be measured only once to accurately measure the passage flow rate of the fluid during the period when the pressure is stable. Further, when the first pressure detecting means stops detecting pressure stability, the second passage flow rate measuring means 14a-3 causes the measuring means to intermittently measure the physical quantity that changes according to the flow velocity of the fluid. While the pressure is not stable, the flow rate of the fluid passing through the flow passage is measured by multiplying the flow velocity corresponding to the physical quantity measured at each intermittent measurement by the cross-sectional area of the flow passage and the time corresponding to the intermittent interval. Therefore, even if the flow rate of the fluid flowing through the flow channel changes moment by moment, it is possible to accurately measure the passing flow rate during that period.

According to a fifth aspect of the present invention, in the apparatus according to the fourth aspect, the pressure in the flow passage detected by the pressure detecting means is constantly and intermittently monitored, and the pressure is the first pressure.
Second pressure detection means 14a-4 for detecting a change exceeding a second predetermined value that is greater than the above value, and the second passage flow rate measurement means includes the second pressure detection means. When the means detects a pressure that has changed by exceeding the second value, the measuring means is caused to intermittently measure a physical quantity that changes according to the flow velocity of the fluid at an interval shorter than the intermittent interval. During the changing period, the flow rate corresponding to the measured physical quantity for each intermittent measurement, the cross-sectional area of the flow passage, and the time corresponding to the short intermittent interval The present invention resides in a flow rate measuring device characterized by measuring a passing flow rate.

According to a fifth aspect of the present invention, there is provided the fourth aspect.
In addition to the action of the described invention, the second pressure detecting means 14a-4 constantly and intermittently monitors the pressure in the flow passage detected by the pressure detecting means, and the pressure is set to a predetermined value larger than the first value. When the second passage flow rate measuring means 14a-3 detects a change exceeding the value of 2, the measurement means intermittently measures a physical quantity that changes according to the flow velocity of the fluid at an interval shorter than the intermittent interval. And the passage of the fluid that has passed through the flow path by multiplying the flow velocity corresponding to the physical quantity measured for each intermittent measurement, the cross-sectional area of the flow path, and the time corresponding to the short intermittent interval, while the pressure is changing. Since the flow rate is measured, the first
Even if a large change in pressure that exceeds a second predetermined value that is larger than the value is caused by the pulsating flow, the measurement interval of the physical quantity is shortened and the passing flow rate can be accurately measured.

According to a sixth aspect of the present invention, in the apparatus according to the fifth aspect, the second pressure detecting means has a value within a predetermined range and an average value corresponding to the intermittent monitoring interval. There is a random time generating means 14a-41 for generating the random time, and the flow rate measuring device is characterized in that the pressure is intermittently monitored at intervals of the random time generated by the random time generating means.

According to a sixth aspect of the present invention, there is provided the fifth aspect.
In addition to the action of the described invention, the first pressure detection means and the second pressure detection means
The pressure detecting means of No. 1 intermittently monitors the pressure at random time intervals generated by the random time generating means 14a-41 having an average value within a predetermined range and corresponding to an intermittent monitoring interval. Since it is performed, even if the pulsating flow is generated, it is possible to synchronize the pressure monitoring interval with the pulsating flow.

According to a seventh aspect of the invention, as shown in the basic configuration diagram of FIG. 1, an instantaneous flow rate measuring means 1 for measuring an instantaneous flow rate which changes according to the flow velocity of the gas in the gas flow path 10, and the flow rate. The pressure detecting means 16 for detecting the pressure in the passage and the pressure in the passage detected by the pressure detecting means are constantly and intermittently monitored so that the pressure does not change beyond a predetermined first value. First pressure detecting means 14a for detecting the stable state
-1, and when the first pressure detecting means detects the stability of the pressure, the measuring means measures the instantaneous flow rate which changes according to the flow velocity of the gas, and the first pressure detecting means stabilizes the pressure. When no longer detected, by multiplying the measured instantaneous flow rate by the time corresponding to the period during which the pressure was stable, the flow rate of the gas passing through the flow path during the period during which the pressure was stable was calculated. When the first passage flow rate measuring means 14a-2 for measuring and the first pressure detecting means stop detecting pressure stability, the measuring means intermittently changes the instantaneous flow rate according to the flow velocity of the gas. In the period in which the pressure is not stable, the flow rate of the gas passing through the flow path is measured by multiplying the measured instantaneous flow rate for each intermittent measurement by the time corresponding to the intermittent interval. Second Excess flow rate measuring means 14a-3, flow rate integrating means 14a-5 for sequentially integrating the flow rate measured by the first flow rate measuring means and the second flow rate measuring means, and integrating by the flow rate integrating means The electronic gas meter is characterized by further comprising a display means 15 for displaying the accumulated flow rate.

In the electronic gas meter according to the seventh aspect, the first pressure detecting means 14a-1 constantly and intermittently monitors the pressure in the flow path 10 detected by the pressure detecting means 16, and the pressure is predetermined. When it is detected that the first value exceeds the first value and is stable, the first passing flow rate measuring means 14a-
2 causes the instantaneous flow rate measuring means 1 to measure the instantaneous flow rate that changes according to the flow velocity of the gas, and when the first pressure detecting means no longer detects pressure stability, the measured instantaneous flow rate and pressure are stable. Since the flow rate of the gas that has passed through the flow path during the period when the pressure was stable is measured by multiplying by the time corresponding to the period, the flow rate of the gas is not flowing when the gas is flowing in the flow path. Assuming that the pressure in the flow channel is stable, it is possible to accurately measure the gas flow rate during the period in which the pressure is stable by measuring the instantaneous flow rate only once when the pressure is stable. Further, when the first pressure detecting means stops detecting the stability of the pressure, the second passing flow rate measuring means 14a-3 intermittently causes the instantaneous flow rate measuring means to change the instantaneous flow rate according to the flow velocity of the gas. Let me measure
During the period when the pressure is not stable, the flow rate of the gas passing through the flow path is measured by multiplying the instantaneous flow rate measured for each intermittent measurement by the time corresponding to the intermittent interval. Even if the flow rate changes from moment to moment, it is possible to accurately measure the passing flow rate during that period. Further, the passing flow rate measured by the first passing flow rate measuring means and the passing flow rate measured by the second passing flow rate measuring means, respectively, is added to the integrating means 14a.
-5 sequentially integrates, and the integrated integrated flow rate is displayed on the display unit 1.
Since 5 is displayed, the integrated flow rate that accurately indicates the gas usage amount is displayed on the display means.

According to an eighth aspect of the invention, in the electronic gas meter according to the seventh aspect, the pressure in the flow passage detected by the pressure detecting means is constantly and intermittently monitored, and the previous pressure is the first pressure. Second pressure detecting means 14 for detecting a change exceeding a second predetermined value larger than the predetermined value.
The second passage flow rate measuring means further includes a-4, and changes according to the flow velocity of the gas when the second pressure detecting means detects a pressure that has changed by exceeding the second value. Measuring the instantaneous flow rate intermittently at intervals shorter than the intermittent interval, and multiplying the measured instantaneous flow rate and the time corresponding to the intermittent interval for each of the intermittent measurements while the pressure is changing. The electronic gas meter is characterized in that the flow rate of the gas passing through the flow path is measured by.

In the electronic gas meter according to the eighth aspect, in addition to the action of the invention according to the seventh aspect, the pressure in the flow passage detected by the pressure detecting means is detected by the second pressure detecting means 14.
When the a-4 constantly monitors intermittently and detects that the pressure has changed beyond a predetermined second value that is larger than the first value, the second passing flow rate measuring means causes the second flow rate measuring means to measure the instantaneous flow rate. In addition, the instantaneous flow rate that changes according to the flow velocity of the fluid is intermittently measured at intervals shorter than the intermittent interval, and it corresponds to the instantaneous flow rate measured at each intermittent measurement during the pressure change and the short intermittent interval. Since the passage flow rate of the fluid that has passed through the flow path is measured by multiplying by the time, even if a large change in pressure exceeding a predetermined second value larger than the first value is caused by pulsating flow, Since the measurement interval of the instantaneous flow rate is shortened, the passing flow rate can be accurately measured, and the integrated flow rate that accurately indicates the gas usage amount is displayed on the display means.

According to a ninth aspect of the invention, in the electronic gas meter according to the eighth aspect, the first pressure detecting means and the second pressure detecting means are within a predetermined range, and the average value is the intermittent value. A random time generating means 14a-41 for generating a random time having a value corresponding to time is provided, and the pressure is intermittently monitored at intervals of the random time generated by the random time generating means. Exists in electronic gas meters.

In the electronic gas meter according to the ninth aspect, in addition to the action of the invention according to the eighth aspect, the first pressure detecting means and the second pressure detecting means are within a predetermined range and have an average value. Since the pressure is intermittently monitored at random time intervals generated by the random time generating means 14a-41, the pressure monitoring interval is a value corresponding to the intermittent monitoring interval, even if a pulsating flow is generated. The pulsating flow can be made non-synchronized, and the integrated flow rate that accurately indicates the gas usage amount can be displayed on the display means.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 shows an electronic gas meter that is configured by incorporating a flow rate measuring device that implements the flow rate measuring method of the present invention. The illustrated electronic gas meter is configured as an ultrasonic type, and is arranged to face each other at a distance L in the gas flow direction in a gas flow path 10 as a flow path in a gas meter for flowing a gas that is a fluid. Two acoustic transducers TD1 and TD2 that operate at ultrasonic frequencies and are made of, for example, piezoelectric vibrators, and acoustics that are arranged opposite to the tube wall 10b that is separated by a distance l in the space 10a that communicates with the gas flow path 10. And a transducer TD3. In the gas flow path 10, both acoustic transducers TD
1, a shutoff valve 10c that shuts off the gas flow path 10 by closing the valve is provided on the upstream side of TD2. A pressure sensor 1 for detecting the pressure in the gas flow passage 10 is provided on the pipe wall of the gas flow passage 10.
6 is provided. As the pressure sensor 16, a semiconductor type sensor can be applied, and these sensors may have low power consumption required for operation due to the operating principle thereof.

Each transducer TD1 and TD2, T
D3 is connected to the transmitting circuit 12 and the receiving circuit 13 via the transducer interface (I / F) circuits 11a and 11b, respectively. Under the control of the microcomputer (μCOM) 14, the transmission circuit 12 transmits a signal for driving one of the transducers TD1 and TD2 to generate an ultrasonic signal in the form of a pulse burst, and an oscillation circuit therefor (see FIG. (Not shown). The receiving circuit 13 has a built-in preamplifier (not shown) that inputs signals from the other transducers TD1 and TD2 that have received the ultrasonic signal that has passed through the gas flow path 10 and processes the ultrasonic signal. . Regarding the transducer TD3, the μCOM 14 controls the transmission circuit 12 and the reception circuit 13 at a timing different from that for the transducers TD1 and TD2, and controls the transmission circuit 12 to drive the transducer TD3 to generate an ultrasonic signal. ,
The same transducer TD3 controls the receiving circuit 13 so as to input the signal generated by receiving the ultrasonic signal reflected from the tube wall 10b.

The pressure sensor 16 is connected to the μCOM 14 via a sensor interface (I / F) circuit 17. The μCOM 14 detects the pressure in the gas flow path 10 by AD-converting and reading the pressure signal generated by the pressure sensor 16 input via the sensor I / F circuit 17 at a predetermined sampling interval. This sampling interval is selected so that the error becomes small.

Further, as shown in FIG. 3, the μCOM 14 is a read-only memory RO which stores a central processing unit (CPU) 14a for performing various processes according to a program, a program for the process performed by the CPU 14a, and the like.
An M14b, a RAM 14c, which is a readable / writable memory having a work area as shown in FIG. 4 used in various processing steps in the CPU 14a, a data storage area for storing various data, and the like are built in, and these are bus lines 14d. Interconnected by.

The CPU 14a in the μCOM 14 uses the pressure sensor 16 input via the sensor I / F circuit 17.
Of the pressure signal generated by the gas flow path is determined by calculating the difference ΔP between the pressures P _{n- 1} and P _n , and determining whether the pressure difference ΔP is less than a predetermined first predetermined value P _1. A pressure detection process is performed to detect whether the pressure inside 10 is stable.

The CPU 14a in the μCOM 14 also performs measurement processing for controlling to alternately switch between the transducer that supplies the signal from the transmission circuit 12 and the transducer that receives the ultrasonic signal in the reception circuit 13, and at the same time between the two transducers. In addition to the flow velocity calculation process for intermittently obtaining the flow velocity of the gas flowing in the gas flow channel 10 by measuring the propagation time of the ultrasonic signal transmitted and received alternately, the calculated flow velocity and the gas flow channel 10 Flow rate calculation processing for obtaining an instantaneous flow rate based on the cross-sectional area is performed.

The CPU 14a in the μCOM 14 further includes
When it is detected that the pressure in the gas flow path 10 is stable, 1
It is possible that the pressure in the gas flow path 10 is not stable due to the pressure determination process that is continuously performed after the subsequent measurement process and the flow rate calculation process are stopped. When it is detected, the transmission circuit 12 and the reception circuit 13 are switched and controlled so as to restart the measurement process and the flow rate calculation process. As a result, the CPU 14a
Is the first drive interval and the transducers TD1, TD
2 is driven to generate an ultrasonic signal, the other is received the ultrasonic signal, sampling is performed at a first time interval to measure the time from the generation of the ultrasonic signal to the reception of the ultrasonic signal, The flow velocity in the gas flow path 10 is calculated by performing calculation based on the measured time.

As described above, when the gas pressure in the gas passage 10 is stable, the CPU 14a assumes that the flow velocity when the gas pressure is stable continues, and the CPU 14a determines the flow velocity when the gas pressure is stable. By measuring once, the instantaneous flow rate corresponding to the flow velocity is calculated by the flow rate calculation process, and this is multiplied by the time during which the gas pressure is stable to obtain the passage flow rate of the gas flowing through the gas flow path 10. Performs a flow rate calculation process.

In addition to the above-mentioned processing, the CPU 14a in the μCOM 14 integrates the calculated instantaneous flow rate by the intermittent time to calculate the passing flow rate. Processing, display processing for displaying the integrated flow rate value obtained by this integrated flow rate processing on the display unit 15, total flow rate value of the gas flow rate in the gas flow path 10 determined in advance (consumed flow rates of the combustors to be connected are summed in advance, (Set) is exceeded, it is determined that an abnormal gas other than the flow rate of gas consumed by the combustor is flowing in the gas flow passage 10 due to a gas hose being pulled out, and the cutoff valve means provided in the gas flow passage 10 The shutoff valve 10c is closed and the total flow rate shutoff process for shutting off the gas flow path is performed.

As described above, when the gas pressure is stable, the CPU 14a performs one measurement process and one flow rate calculation process, and thereafter stops these processes, and the flow rate is measured indefinitely during this stop period. The measurement process and the flow rate calculation process are not performed, and the transducers TD1 and TD2 that consume large power and are not driven by the measurement process. Therefore, it is particularly effective when applied to a gas meter for home use where gas is not always used and the gas is not used for a longer period.

The above-mentioned operation will be specifically described with reference to FIG. 5 showing the relationship between the pressure and the flow rate. When the gas is not in use, there is a high pressure, but the pressure drops as the gas is used. Then, when a pressure change is detected at the timing indicated by A in FIG. 5A, sampling for flow rate measurement is started as shown in FIG. 5B. The x mark in the drawing indicates the sampling timing. When the usage state of the gas is stable and there is no pressure change and the pressure is stable, sampling for flow rate measurement is stopped. Then, when the gas usage situation changes and the pressure becomes unstable at the timing indicated by B in FIG.
As shown in (b), sampling for flow rate measurement is started. Eventually, when the gas is no longer used, the pressure will become constant and stable, and sampling for flow measurement will be stopped again. Since no operation is performed, there is no power consumption associated with the flow rate measuring operation.

The principle of flow rate measurement in the device having the above-mentioned configuration will be described below. CPU1 built in μCOM14
4a outputs a trigger signal to the transmission circuit 12 to generate a pulse burst signal, which is supplied to one of the transducers TD1 and TD2 to generate an ultrasonic signal in this one transducer. In addition, the receiving circuit 13 receives the signal from the other transducer that receives the ultrasonic signal transmitted from the one transducer,
In response to this, the signal generated by the receiving circuit 13 is captured.
After that, the CPU 14a incorporated in the μCOM 14 performs control to repeat the same operation by reversing the transducer that generates the ultrasonic signal and the transducer that receives the ultrasonic signal. Then, the CPU 14 of the μCOM 14
a is a time until a trigger signal is output to the transmission circuit 12 to generate an ultrasonic signal in one of the transducers, and a signal generated by the other transducer that receives the ultrasonic signal is taken in via the reception circuit 13. T1 and T2 are measured, and the flow velocity of the gas flow is determined from the measured times T1 and T2 as described later.

The CPU 14a of the μCOM 14 controls the transducer TD3 at a timing different from the control of the transducers TD1 and TD2, outputs a trigger signal to the transmission circuit 12 to generate a pulse burst signal, and Transducer TD3
To generate an ultrasonic signal in the transducer TD3. Further, the receiving circuit 13 receives the signal from the same transducer TD3 that receives the ultrasonic signal transmitted from the transducer TD3 and reflected by the tube wall 10b, and takes in the signal generated by the receiving circuit 13 in response to this. Then, the CPU 14a outputs a trigger signal to the transmission circuit 12 to cause the transducer TD3 to generate an ultrasonic signal, and the first and second waves of reflection of the ultrasonic signal are generated.
Time Tr1 until the signal generated by the same transducer TD3 that receives the wave is received via the receiving circuit 13,
Measure Tr2 respectively, and measure the measured time Tr1, Tr2
From the above, the sonic velocity in the atmosphere having the same temperature, pressure, and gas species as in the gas flow channel 10 but no gas flow is obtained as described later.

Propagation velocity of sound in stationary gas (sound velocity)
Where c is the flow velocity of the gas flow and v is the propagation velocity of the ultrasonic signal in the forward direction of the gas flow is (c + v). Assuming that the distance between the transducers TD1 and TD2 is L, the time T1 when the ultrasonic signal from the transducer TD1 travels in the same direction as the gas flow and reaches the transducer TD2,
Time T at which the ultrasonic signal from the transducer TD2 travels in the direction opposite to the gas flow and reaches the transducer TD1.
2 means T1 = L / (c + v) (1) T2 = L / (c-v) (2). From equations (1) and (2), v = (L / 2). (1 / T1-1 / T2) = (L / 2). ((T2-T1) / (T2.T1)) (3) , L is known, the flow velocity v can be obtained by measuring T1 and T2.

Note that T2 · T1 = L / (c + v) · (c
−v) = L / (c ² −v ² ), and the flow velocity v is an extremely small numerical value compared to the sound velocity c, so v ^{2 in} the equation is c ²
It can be neglected, which is extremely small as compared with, and T2 · T1 = L / c ² . Then, the above equation (3) eventually, v = ((T2-T1 ) · c 2) / 2 = (T2-T1) · (c 2) · can be rewritten as (1/2). Here, Td = (T2-T
When 1), v = Td · ( c 2/2) = Td · k (4) where a k = c ^2/2.

When the flow velocity v is obtained, the instantaneous flow rate Q
Let S be the known cross-sectional area of the gas flow path 10 and α be the correction coefficient that changes due to the structure of the object and so on. Q = Td · α · S · k = K · Td (5) To be However, K = α · S · k (6) As is clear from the above description, K is a coefficient for correction including many factors such as the speed of sound, gas temperature, and gas pressure.

The sound velocity c in the stationary gas in the equation (6) is communicated with the gas passage 10 as shown in FIG. 2, but is not influenced by the gas flow in the gas passage 10. In the space 10a of the stationary gas, the time until the ultrasonic signal emitted from the third acoustic transducer TD3 is reflected by the wall surface 10b and returns to the transducer is measured,
This time allows the transducer TD3 to move to the wall 10
Since it can be obtained by dividing the round trip distance 2l up to b, the sound velocity c obtained by appropriately performing this measurement may be used.

Therefore, every time the instantaneous flow rate Q is obtained, that is, every time sampling is performed, the passing flow rate Qt is obtained by multiplying the instantaneous flow rate Q by the elapsed time (sampling interval time) from the time point (sampling) previously obtained. It is possible to obtain the integrated gas integrated flow rate Qs, that is, the gas supply amount (gas usage amount), by obtaining and integrating this. And this integrated flow rate Qs
The electronic gas meter can be constructed by displaying the on the display 15.

When it is detected by the above-described pressure determination process that the pressure in the gas passage 10 is not stable, the transducers TD1 and TD are set at the first drive interval.
The ultrasonic signal received by the transducers TD2, TD1 is sampled at the first time interval, but the pressure difference ΔP obtained by the pressure constantly sampled at a predetermined cycle is the second predetermined value. When the value exceeds P ₂ , as a combustor that consumes the gas supplied through the electronic gas meter, for example, a GHP (gas heat pump) that causes pressure fluctuations in the supply gas pressure during gas use is connected, About 15mmH for pressure
_It is determined that a fluctuation of ₂ O is generated at a frequency of 10 to 20 Hz, and that this causes a pulsating flow in which the gas flow velocity changes with time due to the gas flow. When the flow velocity v of the gas flow in which such a pulsating flow is generated is measured at a sampling interval of a constant cycle by the method described above, and the passing flow rate is calculated based on this measured flow velocity, an error occurs and the passing flow rate is The integrated flow rate obtained by integration will be a value different from the actual gas usage.

Therefore, when the pressure difference ΔP obtained by the pressure constantly sampled in the predetermined cycle exceeds the second predetermined value P ₂ which is set in advance, the second time shorter than the first time is set.
The transducers TD1 and TD2 are driven at a drive interval shorter than the first drive interval so that the sampling ultrasonic signal can be sampled at the time interval of.

Since the passing flow rate is obtained based on the propagation time measured by shortening the sampling period when the pulsating flow becomes large as described above, the error due to the pulsating flow occurring when the sampling period is long is reduced. Also, when the pulsating flow becomes smaller, the original long sampling cycle is restored, so the sampling cycle does not remain short and power is not consumed more than necessary, and battery consumption is also minimized. be able to.

In order to prevent the high-speed sampling period from synchronizing with the pulsating flow, the sampling operation may be performed in a random period such that the average value is N seconds.
Therefore, the CPU 14a of the μCOM 14 performs a process for generating a random time, and the random time of the sampling period is selected from a predetermined range so that the average value is N seconds.

Further, since the pulsating flow generated by using the above-mentioned GHP has a constant cycle, when the pressure difference ΔP obtained by the pressure constantly sampled at the predetermined cycle is obtained as described above. If the pulsating flow cycle and the pressure sampling cycle are synchronized with each other, normal pressure cannot be detected. Therefore, in order to eliminate such a situation, the sampling of the pressure in the gas flow path 10 is not a fixed cycle, but a random sampling cycle that changes within a predetermined range so that the average value becomes a predetermined cycle is set to a random number (random ) It may be generated using a generator and the pressure may be sampled by this random period.

The outline of the operation has been described above.
The details will be described below with reference to the flowcharts of FIGS. The CPU 14a starts its operation, for example, by turning on the battery power, and in an initialization step (not shown), initializes various areas formed in the RAM 14c in the μCOM 14, and then proceeds to the first step S1. In step S1, the pressure signal from the pressure sensor 16 input via the sensor I / F circuit 17 is A / D converted to detect the pressure P _n in the read gas flow path 10. Next, in step S2, RA
The pressure stored in the latest pressure P _n storage area 14c1 formed in the work area of M14c is set to the previous pressure P _n-1.
Similarly, the previous pressure P formed in the RAM 14c
_{The n-1} storage area 14c2 is stored, and step S1 is performed.
The pressure P _n detected in step S14 is stored in the latest pressure P _n storage area 14c1 formed in the work area of the RAM 14c. After that, the process proceeds to step S3, and the pressure P _n stored in the latest pressure P _n storage area 14c1 and the previous pressure P _n are stored.
_The pressure difference ΔP, which is the difference from the pressure P _n−1 stored in the _n−1 storage area 14c2, is obtained, and this is calculated as the pressure difference ΔP storage area 14c3 formed in the work area of the RAM 14c.
To store.

Then, the process proceeds to step S4, and step S
It is determined whether or not the pressure difference ΔP obtained in 3 is smaller than the predetermined first pressure value P ₁ . When the determination in step S4 is YES, that is, when ΔP <P ₁ and the pressure is stable, the process proceeds to step S5 and the RAM 14c
It is determined whether the pressure stability flag F1 area 14c4 formed in the work area is 1. If the determination in step S5 is NO, the process proceeds to step S6, where the pressure stability flag F1 area 14c4 is set to 1, and then the process proceeds to step S7 to perform the instantaneous flow rate measurement process described later to detect the instantaneous flow rate Q. Next, in step S8, the instantaneous flow rate Q detected in step S7 is stored in the instantaneous flow rate Q storage area 14c5 formed in the work area of the RAM 14c, and then the process proceeds to step S9.

When the determination in step S5 is YES,
That is, when the pressure stability flag F1 is 1, steps S6 to S8 are skipped and the process proceeds to step S9 where the timer counter T1 area 14c6 for determining the pressure sampling formed in the RAM 14c is set to the first pressure sampling time. After storing the corresponding value, the process proceeds to step S10. The timer counter T1 is decremented every fixed unit time. In step S10, it is determined whether or not the value of the timer counter T1 area 14c6 is 0, and when the determination is NO, it waits until the determination in step S7 is YES. The determination in step S10 is YES
When, that is, when the time corresponding to the pressure sampling period T1 has elapsed and T1 = 0, the process proceeds to step S11 and the sampling number counter CT area 14c7 formed in the work area of the RAM 14c is incremented. Returning to step S1, the pressure P _n in the gas passage 10 is detected again in step S1.

When the determination in step S4 is NO, that is, when the pressure difference ΔP exceeds the predetermined pressure value P ₁ and ΔP ≧ P ₁ and the pressure is no longer stable, the process proceeds to step S12. And the pressure stability flag F1 is 1
Or not, and if this determination is YES, the process proceeds to step S13, and a passage flow rate integrating process described later is performed. That is, in the passing flow rate integrating process of step S12, the passing flow rate is obtained by multiplying the instantaneous flow rate Q stored in the instantaneous flow rate Q storage area 14c5 by the sampling period T1 and the count value of the sampling number counter CT area 14c7. This passing flow rate is the cumulative flow rate Qs storage area 14c8 formed in the work area of the RAM 14c.
It is integrated with the past integrated flow rate Qs stored in. That is, when the pressure is stable and there is no fluctuation in the gas flow rate in the gas flow path 10, the instantaneous flow rate Q when the gas flow rate is reached is multiplied by the period during which the pressure is stable (T1 × CT). , The passing flow rate during the period is calculated, and this is integrated with the past integrated flow rate Qs.

After the processing of step S13, step S
14, the pressure stability flag F1 set to 1 in step S5 is set to 0, and then step S1
Go to 5. In step S15, the above step S
The pressure difference ΔP obtained in 3 is the first pressure value P ₁
As described above, it is determined whether or not the pressure is equal to or less than the second pressure value P ₂ which is determined in advance. When the determination in step S15 is YES, the process proceeds to step S16 to perform the instantaneous flow rate measurement process, and in subsequent step S16 ', step S16 step S16.
After performing the passage flow rate integration processing in 17, the above step S9
Proceed to.

Incidentally, in the instantaneous flow rate measuring process in step S16, the same process as in step S7 described above is performed to detect the instantaneous flow rate Q. In the next step S16 ', the instantaneous flow rate Q detected in step S16 is stored in RAM1.
After storing in the instantaneous flow rate Q storage area 14c5 formed in the work area of 4c, it progresses to step S17. In the passing flow rate integrating process of step S17, step S1
Unlike 3, the instantaneous flow rate Q stored in the instantaneous flow rate Q storage area 14c5 is multiplied by the sampling period T1 to obtain the passing flow rate. This passing flow rate is integrated with the past integrated flow rate Qs stored in the integrated flow rate Qs storage area 14c8 formed in the work area of the RAM 14c. That is, when the pressure is not stable and the gas flow rate in the gas flow path 10 fluctuates, the passing flow rate obtained by multiplying the instantaneous flow rate by the first sampling cycle every time the first sampling cycle T1 elapses. Accumulated.

Further, when the determination in step S15 is NO, that is, when the pressure difference ΔP exceeds the predetermined second pressure value P ₂ , the pressure fluctuation due to the pulsating flow in the gas flow passage 10 is caused. When it is determined that the occurrence of the flow rate has occurred, the process proceeds to step S18, and the instantaneous flow rate measurement process similar to steps S7 and S16 is performed to measure the instantaneous flow rate Q. The measured instantaneous flow rate Q is stored in the instantaneous flow rate Q storage area 14c5 in the subsequent step S19, and then the process proceeds to step S20 to perform a high-speed sampling process which will be described later.
In step 21, a passage flow rate integrating process different from step S17 is performed, and then the process returns to step S1.

In the high-speed sampling processing of step S20, the value corresponding to the second pressure sampling time shorter than the sampling period T1 is stored in the timer counter T2 area 14c9 for determining the high-speed pressure sampling. From this, the timer counter T2 is decremented at a constant unit time, and the process of waiting until the value of the timer counter T2 area 14c9 becomes 0 is performed. Therefore, in the passing flow rate integrating process of step S21, the second sampling is performed at the instantaneous flow rate Q detected at step S18 and stored in the instantaneous flow rate Q storage area 14c5 at step S19 every time the second sampling period T2 elapses. The passing flow rate obtained by multiplying the cycle T2 is integrated.

A typical instantaneous flow rate measuring process in the case of an ultrasonic sensor will be described below with reference to the flowchart of FIG. In the instantaneous flow rate measurement process, first, in step S7a, an ultrasonic wave signal is transmitted from the acoustic transducer TD1, and the time taken for the transmitted ultrasonic wave signal to reach the acoustic transducer TD2 is measured as a propagation time t1. Then step S7b
Then, the acoustic transducer TD2 transmits an ultrasonic signal, and the time taken for the transmitted ultrasonic signal to reach the acoustic transducer TD1 is measured as a propagation time t2.

Thereafter, the process proceeds to step S7c, and the difference Td between the time t2 measured in step S7b and the time t1 measured in step S7a is calculated and stored in the time Td area 14c10 formed in the work area of the RAM 14c. To step S7d. In step S7d, as shown in the above equation (4), the flow velocity v is obtained by multiplying the time Td area 14c10 by the value of the predetermined coefficient k.
Is stored in the flow velocity v area 14c11 formed in the work area of the RAM 14c, and the instantaneous flow rate Q can be determined by multiplying the flow velocity v by the cross-sectional area S of the gas flow channel 10.

In the above-described embodiment, the constant values T1 and T2 are set in the timer counter T1 area 14c6 and the timer counter T2 area 14c9, but a random time generating means is set in the CPU 14a by a program. Alternatively, the random time may be set by causing the random time generating means to generate a random time that varies in a predetermined range with the average values of T1 and T2. With such a configuration, when a pulsating flow occurs in the gas flow path 10 for some reason, it is possible to avoid that the sampling interval is synchronized with the pulsating flow and accurate measurement cannot be performed. Therefore, it is effective.

According to the above-described embodiment, the time Td, which changes according to the flow velocity of the gas when the pressure in the gas flow passage 10 is stable, is measured, and when the pressure becomes unstable, it is measured. Flow velocity v corresponding to time Td and gas flow path 1
Since the cross-sectional area S of 0 and the time corresponding to the period during which the pressure is stable are multiplied to measure the passage flow rate of the gas that has passed through the gas flow path 10 during the period during which the pressure was stable, Assuming that the pressure in the gas flow passage is stable because the gas is not flowing when the gas is flowing in the gas flow passage 10, it is only necessary to measure the time Td once when the pressure is stable. It is possible to accurately measure the gas flow rate during the stable period. When the pressure is not stable, the time Td that changes according to the gas flow rate during that period is measured intermittently, and the flow rate and the gas flow path 10 corresponding to the time Td measured at each intermittent measurement are measured. Since the flow rate of the gas passing through the gas flow path 10 is measured by multiplying the cross-sectional area and the time corresponding to the intermittent interval, the flow rate of the gas flowing through the gas flow path 10 varies from moment to moment. Also, the passing flow rate during that period can be accurately measured.

Therefore, when this flow rate measuring method is applied to a domestic gas meter, it is better that the unused state of the gas is longer and the gas that is a fluid is not flowing. If the number is large, the pressure in the gas flow path 10 is stable, so that when the use of the gas is stopped, it is sufficient to measure the time Td corresponding to the physical quantity only once, and unless the gas is used. , Transducers TD1 and TD
No measurement operation of time Td performed by driving 2 is performed. Therefore, during this period, relatively small power consumption is required, and intermittent reading of the pressure signal from the pressure sensor 16 and its processing are all that is required, and a significant reduction in power consumption is achieved. When operating with a battery as a power source, battery replacement is not required for a long time, which is extremely effective.

Further, not only when the gas is not used but also when the gas is used, the operation of measuring the time Td does not have to be performed as long as the gas constantly flows. Therefore, also from this point, it is possible to reduce power consumption. Further, when the time Td is measured, the gas flow path is determined by the flow velocity v corresponding to the time Td, the cross-sectional area of the gas flow path 10 and the value of the sampling number counter CT corresponding to the time during which the pressure is stable. The flow rate of the gas passing through 10 can be easily obtained.

Further, according to the embodiment, the time Td which changes according to the flow velocity of the gas is intermittently measured at shorter intervals, and the time during which the pressure is changing is measured at each intermittent measurement. Since the flow rate of the gas passing through the gas flow passage 10 is measured by multiplying the flow velocity v corresponding to Td by the cross-sectional area S of the flow passage and the time corresponding to a short intermittent interval, a large change in pressure is detected. Time Td, even when flowing
The measurement interval is shortened and the flow rate can be measured accurately.

Furthermore, according to the embodiment, since the pressure monitoring is performed at random time intervals, even if a pulsating flow is generated, it becomes impossible to detect a pressure change in synchronization with the pulsating flow. It is possible to switch the measurement appropriately when a gas flow occurs.

Further, in the electronic gas meter of the embodiment to which the above-mentioned flow rate measuring method is applied, the flow rate is accurately measured, so that the cumulative flow rate obtained by sequentially integrating the passing flow rates is also accurate and displayed. The accurate integrated flow rate is displayed on the device 15.

In the above-described embodiment, the measuring means 1 is configured as an ultrasonic type flow velocity measuring means and applied to an electronic gas meter, but the flow rate measuring method of the present invention is not limited to the gas meter. It can also be applied to
If the measuring means 1 is capable of intermittently measuring a physical quantity that changes according to the flow velocity of the gas in the flow path 10,
Other types may be used.

Further, in the embodiment, the gas flow rate is measured, but the method and apparatus of the present invention can be equally applied to the accurate fluid flow rate measurement while suppressing the power consumption. .

[0069]

As described above, according to the invention described in claim 1 or 4, the pressure in the flow passage is stable because the fluid does not flow when the fluid flows in the flow passage. As a result, by measuring the physical quantity once when the pressure is stable, it is possible to accurately measure the flow rate of the fluid passing through during the period when the pressure is stable, and the flow rate of the fluid flowing in the flow path changes momentarily. However, since the flow rate can be measured accurately during that period, the flow rate measurement interval can be made extremely long without lowering the flow rate measurement accuracy, and the power consumption can be further reduced. A method and apparatus are obtained.

Further, according to the second or fifth aspect of the invention, even if a large change in pressure is caused by a pulsating flow, the measurement interval of the physical quantity is shortened and the passing flow rate can be accurately measured. Therefore, it is possible to obtain a flow rate measuring method and device that can make the flow rate measurement interval extremely long while enabling accurate flow rate measurement and further reduce power consumption.

Further, according to the invention of claim 3 or 6, even if a pulsating flow is generated, it is not possible to detect a pressure change in synchronization with the pulsating flow. It is possible to obtain a flow rate measuring method and apparatus that can extremely lengthen the flow rate measuring interval without further lowering the measurement accuracy and further reduce power consumption.

According to the seventh aspect of the present invention, it is assumed that the pressure in the flow channel is stable because the fluid does not flow when the fluid is flowing in the flow channel. It is possible to accurately measure the flow rate of the fluid passing during the period when the pressure was stable, even if the flow rate of the fluid flowing in the flow path changes momentarily, by measuring only once.
The passing flow rate during that period can be measured accurately, and the integrated flow rate that accurately indicates the amount of gas used is displayed, so the flow rate measurement interval can be made extremely long without degrading the flow rate measurement accuracy. Even if the power consumption is further reduced by doing so, it is possible to obtain an electronic gas meter in which the error of the flow rate of the gas passing is reduced and the gas usage amount can be accurately integrated and displayed.

According to the eighth aspect of the present invention, even when a large change in pressure is caused by the pulsating flow, the measurement interval of the instantaneous flow rate is shortened and the passing flow rate can be accurately measured. It is possible to obtain an electronic gas meter that can display an integrated flow rate that accurately indicates the amount.

According to the ninth aspect of the present invention, even if the pulsating flow is generated, the pressure monitoring interval and the pulsating flow can be made non-synchronized, so that the integrated flow rate that accurately indicates the gas usage can be displayed. A gas meter is obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing a basic configuration of a flow rate measuring device and an electronic gas meter incorporating the same according to the present invention.

FIG. 2 is a diagram showing an embodiment of a flow rate measuring device and an electronic gas meter incorporating the same according to the present invention.

FIG. 3 is a diagram showing a specific configuration example of a part of FIG.

4 is a diagram showing a part of a work area formed in a RAM shown in FIG.

FIG. 5 is an explanatory diagram for explaining the method of the present invention.

FIG. 6 is a flowchart showing an example of processing performed by a CPU in FIG.

FIG. 7 is a flowchart showing a specific example of a part of the flowchart of FIG.

FIG. 8 is an explanatory diagram for explaining a problem of the conventional method and apparatus.

[Explanation of symbols]

1 Measuring means 10 channels (gas channels) 15 Display means (display) 16 Pressure detection means (pressure sensor) 14a-1 First pressure detecting means (CPU) 14a-2 First flow rate measuring means (CPU) 14a-3 Second flow rate measuring means (CPU) 14a-4 Second pressure detecting means (CPU) 14a-41 Random time generating means (CPU) 14a-5 Flow rate integrating means (CPU)

Claims (9)

(57) [Claims] 1. A physical quantity that constantly and intermittently monitors the pressure in a flow path through which a fluid flows, and that changes according to the flow velocity of the fluid when the pressure is stable and does not change beyond a predetermined first value. And a time corresponding to a period during which the flow velocity corresponding to the measured physical quantity, the cross-sectional area of the flow path, and the pressure are stable when the pressure changes beyond the first value and becomes unstable. The flow rate of the fluid that has passed through the flow path during the period when the pressure is stable is measured by multiplying by, and when the pressure is not stable because it changes beyond the first value, the flow velocity of the fluid Intermittently measuring a physical quantity that changes according to, the period during which the pressure is not stable, corresponding to the cross-sectional area of the flow path and the intermittent interval corresponding to the measured physical quantity for each intermittent measurement By multiplying the time with Flow rate measuring method characterized by measuring the flow rate through the fluid which has passed through the. 2. When the pressure changes over a predetermined second value that is larger than the first value, a physical quantity that changes according to the flow velocity of the fluid is intermittently provided at intervals shorter than the intermittent interval. Measured by a constant, by multiplying the flow velocity corresponding to the measured physical quantity for each intermittent measurement, the cross-sectional area of the flow path and the time corresponding to the short intermittent interval The flow rate measuring method according to claim 1, wherein a flow rate of the fluid that has passed through the flow path is measured. 3. The pressure monitoring interval according to claim 1, wherein the pressure monitoring interval is a random time interval within a predetermined range, the average value of which corresponds to the intermittent interval. Flow measurement method. 4. A measuring means for measuring a physical quantity that changes according to the flow velocity of a fluid in a flow path, a pressure detecting means for detecting a pressure in the flow path, and a flow path in the flow path detected by the pressure detecting means. And a first pressure detecting means for detecting that the pressure is constantly stabilized by not constantly changing and exceeding a predetermined first value, and the first pressure detecting means When stability is detected, the measuring means is caused to measure a physical quantity that changes according to the flow velocity of the fluid, and when the first pressure detecting means stops detecting pressure stability, a flow velocity corresponding to the measured physical quantity. And a cross-sectional area of the flow passage and a time corresponding to a period during which the pressure is stable are multiplied to measure the passage flow rate of the fluid that has passed through the flow passage during the period when the pressure is stable. Passing flow rate measuring means, and the first pressure When the detection means no longer detects the stability of the pressure, the physical quantity that changes according to the flow velocity of the fluid is intermittently measured, and the measured physical quantity is measured for each intermittent measurement while the pressure is not stable. And a second passage flow rate measuring means for measuring the passage flow rate of the fluid passing through the flow passage by multiplying the flow velocity corresponding to the above, the cross-sectional area of the flow passage, and the time corresponding to the intermittent interval. Flow rate measuring device. 5. The pressure in the flow passage detected by the pressure detecting means is constantly and intermittently monitored, and the pressure has changed by exceeding a predetermined second value larger than the first value. Further comprising a second pressure detecting means for detecting, when the second passing flow rate measuring means detects a pressure changed by the second pressure detecting means exceeding the second value, the measuring means. To intermittently measure a physical quantity that changes according to the flow velocity of the fluid at intervals shorter than the intermittent interval, and while the pressure is changing, a flow velocity corresponding to the measured physical quantity for each intermittent measurement. The flow rate measuring device according to claim 4, wherein the flow rate of the fluid that has passed through the flow path is measured by multiplying the cross-sectional area of the flow path by the time corresponding to the short intermittent interval. 6. The first pressure detecting means and the second pressure detecting means generate a random time within a predetermined range in which an average value becomes a value corresponding to the intermittent monitoring interval. The flow rate measuring device according to claim 5, further comprising time generating means, wherein the pressure is intermittently monitored at intervals of random time generated by the random time generating means. 7. An instantaneous flow rate measuring means for measuring an instantaneous flow rate that changes according to a gas flow velocity in a gas flow path, a pressure detecting means for detecting a pressure in the flow path, and a pressure detecting means for detecting the pressure. First pressure detection means for constantly and intermittently monitoring the pressure in the flow path, and detecting that the pressure is stable without exceeding a predetermined first value, and the first pressure detection means. When the means detects pressure stability, the measuring means is caused to measure an instantaneous flow rate that changes according to the flow velocity of the gas, and when the first pressure detecting means does not detect pressure stability, the measurement is performed. First passing flow rate measuring means for measuring the passing flow rate of the gas that has passed through the flow path during the period during which the pressure was stable by multiplying the instantaneous flow rate by the time corresponding to the period during which the pressure was stable; , The first pressure detecting means is When the stability is no longer detected, the measuring means is caused to intermittently measure the instantaneous flow rate that changes according to the flow velocity of the gas, and the measurement is performed for each of the intermittent measurements during the period when the pressure is not stable. Second passing flow rate measuring means for measuring the passing flow rate of the gas passing through the flow path by multiplying the instantaneous flow rate and the time corresponding to the intermittent gap, the first passing flow rate measuring means, and the second passing An electronic gas meter, comprising: a flow rate integrating means for sequentially integrating the passing flow rates measured by the flow rate measuring means; and a display means for displaying the integrated flow rate integrated by the flow rate integrating means. 8. The pressure in the flow path detected by the pressure detection means is constantly and intermittently monitored, and the pressure has changed by exceeding a predetermined second value larger than the first value. Further comprising second pressure detecting means for detecting, when the second passing flow rate measuring means detects a pressure changed by the second pressure detecting means exceeding the second value, The instantaneous flow rate that changes according to the flow velocity is measured intermittently at intervals shorter than the intermittent interval, and during the period in which the pressure is changing, the measured instantaneous flow rate and the short intermittent interval are measured at each intermittent measurement. The electronic gas meter according to claim 7, wherein the flow rate of the gas that has passed through the flow path is measured by multiplying by the corresponding time. 9. The first pressure detecting means and the second pressure detecting means generate a random time within a predetermined range in which an average value is a value corresponding to the intermittent monitoring interval. 9. The electronic gas meter according to claim 8, further comprising time generating means, wherein the pressure is intermittently monitored at intervals of random time generated by the random time generating means.