JP2001174297A - Flow measurement method and flow measurement device - Google Patents

Abstract

(57) [Summary] [Problem] Even if a pulsation occurs in a gas flow, an accurate flow value can be obtained without an error caused by the pulsation being mixed into a gas flow value, and power consumption increases. The present invention provides a gas flow measurement method and a flow measurement device that do not require any gas. SOLUTION: In a flow rate measuring device such as a gas meter, a gas pressure which requires less power consumption than that required for measuring a gas flow velocity value is frequently measured by a gas pressure measuring device 200, and a power consumption amount is measured. Without increasing
A time differential value P 'per unit time of the pressure value P in the pulsation generated in the gas flow is obtained, and an error δv included in the gas flow velocity value v is calculated based on the value P' to correct the measurement error. The circuit 300 adds or subtracts the error δv from the gas flow rate value v to correct the error of the gas flow rate value v, and finally obtains a gas flow value with a small error.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a flow rate measuring method and a flow rate measuring device.

[0002]

2. Description of the Related Art As a typical example of a flow meter, a gas meter is a typical example. In a so-called guess-type flow meter or a flow measuring method such as a heat flow sensor system, an ultrasonic system or a fluidic system. The flow velocity of a fluid such as gas flowing from the upstream side to the downstream side is intermittently measured at a predetermined sampling frequency (measurement frequency), and the flow rate value at the time of the measurement is obtained based on the measured flow velocity value and the like. In addition, the flow rate value is further integrated.

[0003] By the way, in a guess-type gas meter which is an example of the conventional flow rate measuring device as described above, when a pulsation occurs in a gas flow flowing through a gas pipe, measurement is performed due to the pulsation. There was a tendency for errors in (including) flow rate values.

In order to prevent such an error from occurring, it is conceivable to first install a fluid mechanical pulsation absorbing device such as a governor. Alternatively, even if a pulsation occurs in the gas flow, the gas flow velocity is measured at a sampling frequency that is equal to or higher than the average frequency of the pulsation,
It is considered that an error due to pulsation can be prevented from occurring in the gas flow rate value by obtaining the average value or the like.

[0005]

However, when a fluid mechanical pulsation absorbing device such as a governor is installed, the number of components increases and the structure of the flow rate measuring device as a whole becomes complicated. However, there is a problem that the cost is increased. In addition, when measuring the gas flow rate using an inferential flow measurement device such as an ultrasonic flow measurement device, when measuring the gas flow velocity at a sampling frequency equal to or higher than the average frequency of gas pulsation, Therefore, there is a problem in that the amount of power consumed increases, and a power supply battery used in the gas meter can be used only for a relatively short period of time. Further, if an attempt is made to avoid such an increase in power consumption, frequent measurement of the gas flow rate becomes substantially impossible, and as a result, an error occurs in the measured value of the gas flow rate due to the pulsation generated in the gas flow. It was inevitable to do.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to eliminate the need for installing a fluid mechanical pulsation absorbing device such as a governor when pulsation occurs in a fluid such as a gas flow. In addition, without causing an increase in power consumption consumed for measurement, it is possible to obtain a highly accurate flow rate measurement value by minimizing mixing of errors due to pulsation in the fluid as much as possible. It is to provide a measuring method and a flow measuring device.

[0007]

A flow rate measuring method and a flow rate measuring apparatus according to the present invention intermittently measure a flow rate or a flow rate of a fluid at a predetermined frequency, and based on the measured value, measure the flow rate of the fluid. In the method, the fluid pressure is sampled at a higher frequency than the sampling frequency for measuring the flow rate or the flow rate, and based on the value of the sampled pressure, an error generated in the measurement value due to the pulsation of the fluid is calculated. It is characterized in that it is corrected.

Further, a correction value for correcting an error in the measured value may be obtained based on the amount of change in pressure per unit time, and the error in the measured value may be corrected using the corrected value.

More specifically, it is a desirable mode to obtain a correction value proportional to the amount of change in pressure per unit time and to correct an error in a measured value using the correction value.

It is a desirable embodiment to obtain the flow rate value by taking the average value of the measured values of the flow rate or the flow velocity every predetermined number of times of measurement. For example, a flow measurement method or device that intermittently measures the flow rate or flow velocity of a fluid, such as a thermal flow sensor method, a guess type gas meter such as an ultrasonic wave propagation method or a fluidic method, etc. The present invention can be suitably used.

That is, in the flow rate measuring method and the flow rate measuring apparatus according to the present invention, accurate measurement is generally possible, but frequent measurement requires a large amount of power consumption. Therefore, it is generally possible to measure the flow rate and flow rate at a general frequency while measuring the flow rate and flow rate with a lower power consumption than measuring the flow rate. Thus, much information about the pulsation can be obtained without increasing the power consumption, and an error in the measurement value of the flow rate or the flow velocity due to the pulsation of the fluid is corrected based on the pressure value. In this way, an error of the measured value is finally minimized and a highly accurate flow measured value is obtained without causing an increase in power consumption required for measuring the flow rate or the flow velocity of the fluid.

Here, the inventors of the present invention have found that the error of the measured value of the flow rate or the flow velocity caused by the pulsation has a strong correlation with the amount of change per unit time of the pressure value caused by the pulsation. confirmed. Therefore, by measuring the pressure value that does not cause an increase in power consumption even if frequent sampling is performed as described above, the pressure value of the fluid at that time is obtained,
By performing a predetermined calculation on the value, a measurement error of the flow velocity or the flow rate caused by the pulsation is estimated. Alternatively, the measurement error of the flow rate is inferred by using a table carrying information on the correspondence between the pressure value and the corresponding correction value. Then, the value of the estimated error is added or subtracted from the measured value of the flow velocity or the flow rate actually measured at that time to correct the measurement error at that time. The error is corrected in this way, and based on the more accurate measured value of the flow velocity or the flow rate, the error is finally suppressed as small as possible to obtain a highly accurate flow rate measured value.

The correction of the flow rate value is performed by correcting an error contained (mixed) in the measured flow rate or flow rate measurement value, so that the corrected measurement value is obtained. The calculated flow rate value may be set so that the error is finally as small as possible. Alternatively, first, the flow rate value is calculated based on the measurement value including the error, and the calculated flow rate value is included in the flow rate value. Needless to say, the estimated error may be estimated based on the pressure value, and the flow rate value once calculated may be corrected using the estimated value of the error.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram showing a configuration of a main part of a gas meter which is an example of a flow measurement device that measures a flow value using a flow measurement method according to the present invention.

This gas meter uses a gas flow rate measuring device 10 for measuring a measured value v of a gas flow rate using a heat flow sensor.
0, a gas pressure measuring device 200 that measures the gas pressure value P using a pressure sensor, and the amount of change in the measured pressure value P per unit time; dP / dt (this is referred to as P ′. The same applies hereinafter. ) Is calculated, and a correction value for correcting an error (hereinafter referred to as δv; hereinafter the same) occurring in the measured value v of the gas flow velocity due to the pulsation of the gas is estimated based on the calculated value. A measurement error correction circuit 300 that corrects the measured value v of the gas flow velocity to a more accurate value by using the above, and obtains a gas flow velocity value Vave while minimizing an error, and a gas flow rate based on the corrected gas flow velocity value Vave The value Q is calculated, and the value Q is successively integrated in a time series to obtain a gas flow integrated value (ΣQ).
And a gas flow rate integrating circuit 400 for obtaining

The gas flow rate measuring device 100 measures a physical quantity such as a flow rate or a temperature gradient relating to a gas flow that changes in accordance with the gas flow rate, and based on the measured gas flow rate value v
A flow velocity measuring device 101 that outputs an electric signal corresponding to the above, a gas flow velocity value calculation circuit 102 that generates data of the gas flow velocity value measured at that time based on the signal output by the flow velocity measuring instrument 101, and The main part is constituted from. In this embodiment, the gas flow velocity measuring device 100 is of an inferential type such as a heat flow sensor type for measuring a gas flow velocity value v.

The gas pressure measuring device 200 includes a pressure detecting element 201 such as a pressure sensor for detecting the pressure of a gas, and a gas sensor based on an electric signal output from the pressure detecting element 201 corresponding to the gas pressure. A gas pressure value calculation circuit 202 for obtaining data of the pressure value P constitutes a main part thereof, and changes in the gas pressure value P and its unit time at the time when the gas flow velocity value v is measured. The amount (time derivative) P ′ is measured, and the gas flow velocity v
The gas flow velocity value v is higher than the sampling frequency of
Is to measure the pressure value P near the time point when is measured. More specifically, when the gas flow velocity value v is measured once at a certain point in time, the pressure value P is measured a predetermined number of times before and after the measurement point at one point. For example, assuming that the number of measurement of the pressure value P is set to be a total of 20 before and after one measurement of the gas flow velocity value v, one measurement of the gas flow velocity value v becomes one.
The pressure value at each measurement timing and the pressure values P before and after each measurement are measured ten times. Based on the measured value P of the gas pressure thus measured, a change amount P 'of the pressure value P per unit time is obtained.

As a more specific method, the gas pressure value P1 at that time is measured in synchronization with the measurement timing of the gas flow velocity value v at a certain time t1, and the next Δt
The difference ΔP = P2−P1 from the pressure value P2 measured at the later measurement timing t2 is taken, and based on these ΔP and Δt, the change amount P ′ = ΔP of the pressure value P per unit time at that time. / Δt = (P2−P1) / (t2−t1) is obtained. Alternatively, before and after the measurement timing of the gas flow velocity v at the time t1, for example, the pressure P
, And the average value is defined as P1.
The pressure value P may be measured ten times before and after the measurement timing t2 after t, and the average value may be used as P2.

The change amount P 'of the pressure value per unit time obtained in this manner is the displacement δP (= P') of the gas pressure caused by the pulsation at that time. By obtaining δP in this manner and performing an operation using a predetermined proportionality constant with respect to δP, it is inferred that the gas flow velocity value v is caused by the pulsation at that time. An error value δv can be obtained.

Here, in obtaining the above P ′,
It is needless to say that it is desirable to obtain as many measured values as possible of the gas pressure P from which P 'is obtained. In order to obtain such a large number of measurement values, it is necessary to sample the measurement of the pressure value P many times, but in general, measurement of pressure (such as measurement by a pressure sensor)
Can be executed with extremely low power consumption compared to the measurement of flow rate and flow velocity (measurement with a guess-type sensor such as a flow sensor), so that a sufficiently reliable δP can be obtained by consuming only a small amount of power. You can do it.

The measurement error correction circuit 300 multiplies δP obtained as described above by a predetermined proportionality coefficient k, and calculates the error value δv contained in the gas flow velocity value v measured at that time. The gas flow velocity value v is corrected by calculating (guessing) and adding or subtracting the value δv from the gas flow velocity value v to obtain a more accurate gas flow velocity value Vave in which errors are minimized. is there. Here, the value δv of the error generated in the gas flow velocity value v due to the pulsation is δv = v between Vave and a stable gas flow velocity in the case where no pulsation occurs. -Vave is a value that satisfies the relational expression of Vave, that is, a pulsating displacement of the gas flow velocity centered on the true value Vave of the gas flow velocity value estimated as an accurate gas flow velocity value. As will be described later, the pulsating displacement δv of the gas flow velocity and the displacement δP of the amount of change in the pressure value per unit time have a strong correlation such as a proportional relationship. In
A proportional constant k in the proportional relation is prepared in advance by various experiments or the like, and δP is calculated using the proportional constant k.
Δv can be calculated from

The gas flow rate integrating circuit 400 integrates the gas flow rate value Vave obtained by correcting the gas flow rate value v measured by the gas flow rate measuring device 100 by the measurement error correction circuit 300 as described above. The Vave is integrated, data of the integrated value (= ΣQ) of the gas flow rate (gas usage amount) Q is obtained from the integrated value, and the obtained data is stored in, for example, a RAM (Random Access Memory).
The information is recorded on a recording element (not shown) as shown in FIG.

When a pulsation is generated in the gas flow when the gas flow velocity measuring device 100 measures the gas flow velocity v, the pulsation is caused by the pulsation as shown schematically in FIG. The middle v (t)) pulsates. Further, at this time, the temporal change of the gas pressure value P, that is, the pressure value P
Is the displacement δP of the differential value P ′ of
Is displaced almost in proportion to. Therefore, such δP and δ
and v is determined in advance based on experimental values obtained from various experiments, and the proportional coefficient k is multiplied by the value of δP calculated by frequent measurement to obtain a gas. An error δv due to flow pulsation, that is, a displacement δv of the gas flow velocity v from the true value Vave can be calculated.

For example, in the example shown in FIG. 2, δv / δP
Is about 3/1, so that the proportionality coefficient k in this case is k = 3. That is, the error δv of the gas flow velocity v can be calculated by multiplying the value of δP by the proportional coefficient k = 3, and the value of the error δv thus obtained is added to or obtained from the measured value of the gas flow velocity v. By subtracting (v−δv = Vave), it is possible to obtain a gas flow velocity value that does not include an error caused by pulsation as much as possible, that is, a true value Vave of the gas flow velocity.

The theoretical support for the error value due to such pulsation, that is, the proportional relationship between the displacement δv of the gas flow velocity v from the true value Vave and the displacement δP of the gas pressure P is as follows. It is considered that the explanation can be simplified as follows. That is, first, the conducting path 1 for conducting the gas flow from the upstream side to the downstream side in the gas meter to measure the gas flow rate and the pressure is a straight pipe having a cross-sectional area S as schematically shown in FIG. As an example, consider a cylindrical (irregular) fluid element G in the gas flow having a cross-sectional area the same as that of the straight pipe of the conduit 1 and a unit length. The fluid element G can freely exchange heat with the outside, and its temperature is always constant.

Now, the displacement per unit time (the displacement of the longitudinal wave in the direction parallel to the longitudinal direction of the straight pipe) is δv
If the pulsation is as follows, the volume displacement amount of the fluid element G per unit time at this time (referred to as ΔG) is ΔG = −S · δv. On the other hand, during the unit time, the pressure value P of the fluid element G changes by δP from a value before displacement due to pulsation (this is referred to as Pave; the same applies hereinafter), and becomes P2 = Pave + δP. The volume G of the element G is calculated as G2 = G1 + from a value before displacement caused by pulsation (this is referred to as G1; the same applies hereinafter).
Assuming that the temperature has changed to ΔG, Boyle's law can be applied from the assumption that the temperature is constant, and Pave ·
G1 = P2 · G2 holds, and P2 =
Pave · G1 / G2 is derived. From the above assumption, G1 = S and G2 = (1−δv) · S hold. Then, the pressure change amount P ′ per unit time, that is, δP, is δP = P2−Pave = (Pave · G1
/G2)-Pave=Pave.(G1-G2)/G2
Becomes This equation further shows that δP = −ΔG · Pave /
(1−δv) S = S · δv · Pave / (1−δv) S
Becomes This means that δP = Pave · δv / (1−
δv). Here, δv which is the displacement of the gas pulsation
Can be generally considered to be a sufficiently small value (1 >> δv), and can be approximately regarded as 1−δv = 1. Then, from the above equation, the result of δP = Pave · δv is obtained. In this equation, Pave is a constant gas flow pressure value when no pulsation occurs, and can be regarded as a constant. Therefore, it is theoretically analyzed that a proportional relationship of δP = Pave · δv is approximately established between δP and δv, using Pave as a proportional constant.

In the theoretical analysis thus modeled, the displacement δP of the temporal differential value P ′ of the pressure value P and the error of the gas flow velocity (ie, the displacement of the gas flow velocity) δv are in a proportional relationship. Although it was possible to prove that, the proportional relationship between δP and δv as described above also occurred in the pulsation of the gas flow flowing in the actual gas meter, in which various factors such as a complicated eddy current and a loss head were involved. It is necessary to confirm whether or not the condition holds by an experiment using a gas meter. Then, the inventors of the present invention used a gas pipe and a gas consuming device as shown in FIG. 4 and a gas meter of the present embodiment, and in a state where pulsation was actually generated, the unit of the pressure value P at that time was used. An experiment was conducted to confirm the relationship between the amount of change P 'per time and the displacement δv of the gas flow velocity. This experiment shows that GH, which tends to generate pulsation,
A gas consuming device such as a P (gas heat pump) 600 is used in the neighbor's house, and the pulsation is caused by the gas piping 601a, 6b.
The measurement was carried out under the condition that the gas flow rate and the gas pressure were measured by the gas meter 700 so as to influence the gas meter 700 via 01b. At this time, the gas consuming device 800 connected to the downstream side of the gas meter 700 is in a state where gas consumption is stopped in this experiment so that pulsation does not occur in the gas flow due to itself. And

Under such a simplified condition setting,
The gas meter 700 sets the gas flow rate value v at a measurement cycle of 1 Hz, and changes the pressure change value P ′ per unit time to 100.
Each measurement was performed at a measurement cycle of Hz. The result is shown in FIG.
Shown in The gas flow rate value Q obtained based on the measured gas flow velocity value v is a value that fluctuates greatly at every one-second cycle as indicated by the thick line, and the value of the temporal change in pressure. As for P ′, as shown by the thin line, extremely fine fluctuations are recorded based on the measurement that is about two digits more frequent than the measurement frequency of the gas flow rate value Q. As shown in FIG. 5, the rough tendency is clearly shown.
In order to confirm in more detail the relationship between the measured gas flow velocity value v and the value P ′ of the temporal change in pressure, the experimental conditions were set as described above, and the values of P and v were changed. Both were measured at 1000 Hz (1 KHz), which was higher frequency than the above, and data were obtained. FIG. 6 shows the result. In FIG. 6, the change (transition) of P ′
Is shown by a thin line graph, and the change (transition) of v is shown by a thick line graph. As is clear from this graph, during the time from when the experiment was performed t = 1 to t = 2, v
It was clearly confirmed that and P ′ fluctuated while showing a very strong correlation and linking.

Further, in the experimental system shown in FIG.
An experiment was conducted to confirm the relationship between the variation P 'of the pressure value P per unit time and the displacement δv of the gas flow rate at that time with the gas flow flowing at 300 L / h on the 0 side. . At this time, the value of P and the value of v were both measured at 1000 Hz (1 KHz) to obtain data. FIG. 8 shows the result. In FIG. 8, similarly to FIG. 6, the change (transition) of P ′ is shown by a thin line graph, and the change (transition) of v is shown by a thick line graph. In FIG. 8, the scale of the value of the instantaneous flow rate v and the scale of the pressure displacement P ′ (= δP) both plot the output voltage [mV] from the sensor. Needless to say, the actual flow value v and the value of the pressure displacement can be obtained by multiplying by a constant. Also, in the scale of FIG.
The flow rate v = 300 [L / h] corresponds to the position of the scale of 1.12 [mV] as shown by the one-dot chain line in FIG. As is clear from this graph, between the time t = 1 and t = 2 at which the experiment was performed, v and P ′ also fluctuate while showing a very strong correlation and linking. Could be confirmed.

Further, the gas flow rate value v is measured at a measurement cycle of 1 Hz using the gas meter according to the present invention provided with the above-described measurement error correction circuit 300, and the pressure time is measured. The value of the target change P 'is 10
An experiment was performed in which measurement was performed at a measurement cycle of 0 Hz, a correction value was calculated based on the value of P ′, and the correction value was added or subtracted from the gas flow velocity value v to obtain a true value Vave of the gas flow velocity. The results are shown in Table (A) and Graph (B) of FIG.

As is clear from the experimental results shown in FIG. 7, the measured gas flow velocity (so-called instantaneous flow velocity) v is greatly deviated from the true value of 0 in this experiment to about 0.57 at the maximum. However, the gas flow velocity value Vave obtained by correcting such a measurement error by the correction value δv calculated based on the displacement δP value of P ′ is 0.17 even at the maximum deviation. It has been confirmed that an improvement of more than three times the accuracy can be achieved. In addition, the gas flow integrated value ΣQ obtained by integrating the gas flow velocity value Vave obtained by performing the correction in this manner is also calculated by the integration time according to the conventional method to which the error correction according to the present invention is not applied. As a result, when the error correction according to the present invention is applied, it is possible to suppress the variation by as much as one order of magnitude. It has been confirmed that the gas flow rate has almost changed to 0, which is the true value of the gas flow integrated value ΣQ.

As described above, the gas pressure at which the power consumption is smaller than that required for measuring the gas flow velocity value is frequently measured by the gas pressure measuring device 200, and the pressure in the pulsation generated in the gas flow is measured. The displacement δP of the value P is obtained, the δP is multiplied by the proportionality coefficient k, and an error δv estimated to be included in the gas flow velocity v is calculated. By subtracting, the error of the gas flow velocity value v is corrected. As a result, an error included in the measured value can be reduced as much as possible without causing an increase in power consumption, and a more accurate gas flow velocity value v can be obtained. Based on this, an accurate integrated value ΣQ of the gas flow rate Q can be obtained. Can be obtained.

In the present invention, a heat generating means is provided in the conduction path, and a temperature measuring device is provided on each of the upstream side and the downstream side, and it is determined that the temperature drop between them changes according to the gas flow rate. In addition to gas meters of the thermal flow sensor type (or thermal flow rate measuring type) that measure the flow rate of gas fluid by utilizing,
Geophones are arranged facing each other, ultrasonic waves are propagated between them, and the flow rate of the gas fluid is adjusted using the propagation time difference and Doppler effect generated in the ultrasonic waves according to the flow velocity of the gas fluid passing through the conduction path. It is necessary to measure the flow rate of a so-called guess-type gas meter, such as a gas meter of an ultrasonic propagation method to be measured, or a gas meter other than the gas meter, for example, by transmitting a relatively strong ultrasonic wave to a fluid having a high sound attenuation rate. The present invention can be suitably applied to a flow rate measuring method and a flow rate measuring device.

Further, in the above embodiment, the error δv included in the measured gas velocity value v is calculated, the gas velocity value v is corrected using the calculated value, and the resultant value is calculated based on the error δv. The error of the gas flow rate value is corrected. However, by calculating (guessing) the error of the gas flow rate value Q from the gas pressure value and adding or subtracting it from the gas flow rate value Q, It goes without saying that the error of the flow rate value Q may be corrected.

Further, it goes without saying that the above-mentioned measured value error correction circuit 300 and gas flow rate integrating circuit 400 may be implemented by software in a microcomputer or may be constructed by a discrete circuit.

[0036]

As described above, according to the flow rate measuring method and the flow rate measuring apparatus of the present invention, the flow rate measurement value can be obtained by pulsation in a fluid such as a gas flow without causing an increase in power consumption. By correcting the generated error, it is possible to obtain an accurate flow rate value with the error being minimized. Moreover, such an accurate flow rate value can be realized by consuming only a small amount of power.

[Brief description of the drawings]

FIG. 1 is a diagram showing a main part of a configuration of a gas meter according to an embodiment of the present invention.

FIG. 2 is a diagram schematically showing a state in which a gas flow velocity and a pressure are pulsatively displaced.

FIG. 3 shows a fluid element G for explaining theoretically supporting that a displacement amount δv of a gas flow velocity v from a true value Vave and a value P ′ of a temporal change of a gas pressure have a strong correlation. FIG.

FIG. 4 is a diagram showing an experimental device (equipment) for confirming the relationship between P ′ and δv in a state where pulsation is actually generated.

FIG. 5 is a diagram showing an experimental result for confirming a relationship between P ′ and δv in a state where pulsation is actually generated.

FIG. 6 shows that the values of P ′ and v are frequently measured when the gas flow rate on the gas meter side is 0 [L / h], and it is confirmed that there is an extremely strong correlation between the two. It is a figure showing an experimental result.

FIG. 7 shows an actual function of a gas meter to obtain accurate gas flow velocity value v, gas flow rate value Q, and integrated gas flow rate value ΣQ.
FIG. 7 is a diagram showing a table (A) and a graph (B) of an experimental result for confirming that is obtained.

FIG. 8 shows a gas flow rate of 300 [L / h] on the gas meter side.
FIG. 13 is a diagram showing experimental results in which the values of P ′ and v were measured at high frequency in the case of and that there was an extremely strong correlation between them.

[Explanation of symbols]

100─ gas flow rate measuring device, 200─ gas pressure measuring device, 300─ measurement error correction circuit, 400─ gas flow rate integrating circuit

Continued on the front page (72) Inventor Takeshi Ken Tashiro 36-3 Sunakubo, Kawagoe-shi, Saitama Prefecture (72) Inventor Kenichiro Yuasa 2-32-25 Jindaiji, Kanagawa-ku, Yokohama-shi, Kanagawa F-term (reference) 2F030 CA03 CA10 CB09 CC13 CD17 CE04 CF07 CF20 2F031 AC03 2F035 GA02

Claims (8)

[Claims] 1. A flow rate measuring method for intermittently measuring a flow rate or a flow rate of a fluid at a predetermined frequency and obtaining a flow rate value of the fluid based on the measured value. Sampling the pressure of the fluid at a higher frequency than the frequency and correcting an error generated in the measurement value due to the pulsation of the fluid based on the value of the sampled pressure. Method. 2. The method according to claim 1, wherein a correction value for correcting an error of the measured value is obtained based on a change amount of the pressure per unit time, and the error of the measured value is corrected using the corrected value. The flow measurement method according to claim 1, wherein 3. The flow rate measurement according to claim 1, wherein a correction value proportional to a change amount of the pressure per unit time is obtained, and an error of the measurement value is corrected using the correction value. Method. 4. The flow rate measuring method according to claim 1, wherein the flow rate value is obtained by taking an average value of the measured values of the flow rate or the flow velocity every predetermined number of times of measurement. 5. A sampling device for intermittently measuring a flow rate or a flow rate of a fluid at a predetermined frequency and obtaining a flow rate value of the fluid based on the measured value. Sampling the pressure of the fluid at a higher frequency than the frequency and correcting an error generated in the measurement value due to the pulsation of the fluid based on the value of the sampled pressure. apparatus. 6. A method for determining a correction value for correcting an error in the measured value based on a change amount of the pressure per unit time, and correcting the error in the measured value using the corrected value. The flow measurement device according to claim 5, wherein 7. The flow rate measurement according to claim 5, wherein a correction value proportional to an amount of change in the pressure per unit time is obtained, and the error of the measured value is corrected using the correction value. apparatus. 8. The flow rate measuring device according to claim 5, wherein the flow rate value is obtained by taking an average value of the measured values of the flow rate or the flow velocity every predetermined number of times of measurement.