JP3822771B2 - Flow rate measuring method and flow rate measuring device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a flow rate measurement method and a flow rate measurement device, and more particularly to a flow rate measurement method that integrates values obtained by intermittently measuring a flow rate or a flow rate of a fluid and a flow rate measurement device that executes the method.
[0002]
[Prior art]
In general, in a so-called estimation type gas meter such as an ultrasonic measurement type gas meter, the gas flow rate is measured intermittently and the measured values are integrated to obtain an integrated gas flow rate value, that is, an integrated value of gas usage. ing.
[0003]
However, if pulsation occurs in the gas flow, an error may occur in the gas flow rate value measured at that time. For example, one of two neighboring households sharing a gas main pipe uses a gas consuming appliance such as a gas heat pump that tends to generate pulsation, and the other household also uses gas. Under the circumstances, not only a home gas meter that uses a gas consuming appliance that is prone to pulsation, but also pulsation occurs in the gas flow in the other household piping. In some cases, an error may occur (included) in the measured value of the gas flow rate due to the above, and a large error may occur in the integrated gas flow rate.
[0004]
That is, when the timing of intermittently measuring the gas flow rate and the phase of pulsation are almost synchronized unexpectedly, for example, a value close to the maximum value of pulsation is periodically measured. If measured values including errors different from the flow rate values are measured in the same way each time and are accumulated one after another, the gas flow rate integrated value including a large error may eventually be obtained.
[0005]
In order to prevent the occurrence (mixing) of errors due to such pulsation, it has been proposed to install a device for eliminating the pulsation of gas, etc., but the overall configuration by attaching the device In addition, the manufacturing cost and the parts cost are further increased, and there is a problem that the cost of the entire gas meter is further increased.
[0006]
Therefore, in the conventional gas meter or the gas flow rate measurement method used for it, the pressure fluctuation caused by the pulsation of the gas is detected, and based on the pressure fluctuation, the period and phase of the pulsation occurring at that time are grasped, For example, Japanese Patent Laid-Open No. 10-197303 proposes a method of intermittently measuring a gas flow rate or a gas flow rate at the same period or the same phase as the pulsation period or phase.
[0007]
[Problems to be solved by the invention]
However, in practice, there is an error in the measurement of pulsation generated in the gas flow, or the pulsation period itself is not necessarily constant and may change every moment. It is difficult to measure the gas flow rate completely in the same cycle or in the same phase with respect to the phase. As a result, the gas flow rate value including the error, that is, the gas flow rate value deviating from the pulsation center value is periodically measured. As a result, they are accumulated one after another, and eventually there is a problem that the gas flow rate integrated value includes a large error.
[0008]
The present invention has been made in view of such problems, and its purpose is to accurately measure the fluid flow rate value or the fluid flow rate integrated value obtained by integrating the fluid flow rate value even when pulsation occurs in the fluid. An object of the present invention is to provide a flow rate measuring method and a flow rate measuring device that can be used.
[0009]
[Means for Solving the Problems]
The flow rate measurement method according to the present invention repeats intermittently measuring the flow rate or flow velocity value of the fluid flowing from the upstream side to the downstream side at a predetermined frequency per measurement period, and every measurement period. In the flow rate measuring method for integrating the values obtained in the above, the start phase of the measurement period is changed based on a predetermined regularity.
[0010]
The period or phase of pulsation generated in the fluid is measured, and the start phase of the measurement period is set to a predetermined value so that the period or phase of the start timing of each measurement period is different from the period or phase of pulsation. It is a preferable aspect to change based on regularity.
[0011]
Moreover, it is a preferable aspect to repeatedly measure the cycle or phase of the pulsation of the fluid at a frequency higher than a predetermined frequency based on the pressure value of the fluid.
[0012]
The flow rate measuring device according to the present invention repeats intermittently measuring the flow rate or flow velocity value of the gas flowing from the upstream side to the downstream side at a predetermined frequency per measurement period, a plurality of times. What is obtained by integrating the values obtained for each time to obtain an integrated flow rate value of the fluid is characterized by comprising start phase control means for changing the start phase of the measurement period based on a predetermined regularity. .
[0013]
The pulsation measuring means for measuring the pulsation period or phase generated in the fluid is further provided, and the start phase control means is configured such that the period or phase of the start timing of the measurement period is different from the pulsation period or phase. It is a preferable aspect to change it.
[0014]
Moreover, it is a preferable aspect that the pulsation measuring means measures the period or phase of gas pulsation at a frequency higher than a predetermined frequency based on the pressure value of the fluid.
[0015]
Further, the flow rate measuring apparatus includes an ultrasonic flow rate measuring unit that propagates ultrasonic waves to the fluid and measures the flow rate or flow velocity of the fluid based on the propagation time of the ultrasonic waves. Is a desirable embodiment. That is, the present invention is particularly suitable for an ultrasonic measurement type flow rate measuring apparatus. However, the present invention is not limited to this, and if it is a flow rate measuring device that intermittently measures the flow rate of fluid, various other flow rate measurement methods such as a fluidic method or a pressure difference measurement method are used. Needless to say, the present invention can also be applied to an apparatus.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0017]
FIG. 1 is a diagram showing an outline of the configuration of the main part of a gas meter according to an embodiment of the present invention. This gas meter is an ultrasonic transmitter / receiver 2a, 2b that oscillates ultrasonic waves intermittently at a predetermined frequency per measurement period with respect to a gas flowing from the upstream side to the downstream side of the conduction path 1, and oscillation. A control circuit 2c, a gas flow rate calculation circuit 3 for measuring the gas flow rate v based on the propagation time of the ultrasonic wave, and a gas flow rate value integration circuit 4 for integrating the gas flow rate values obtained for each measurement period. Further, a time interval Td is provided between the measurement periods T, and the length of the plurality of time intervals Td is stored in an information recording device (not shown) or the like. And a start phase control circuit 5 that changes based on regularity.
[0018]
The ultrasonic transmission / reception devices 2a and 2b are controlled by the oscillation control circuit 2c and intermittently propagate ultrasonic waves at a predetermined frequency per one measurement period. The propagation of the ultrasonic waves is executed so that the propagation from the upstream side to the downstream side and the propagation from the downstream side to the upstream side are repeated alternately.
[0019]
The gas flow velocity calculation circuit 3 measures the gas flow velocity v based on the ultrasonic wave propagation time. More specifically, based on the time difference between the propagation time of the ultrasonic wave from the upstream side to the downstream side and the propagation time of the ultrasonic wave from the downstream side to the upstream side, the gas flow velocity v at that time is It is to be measured.
[0020]
The conduction path 1, the ultrasonic transmission / reception devices 2a and 2b, the oscillation control circuit 2c, and the gas flow rate calculation circuit 3 may be the same hardware as the conventional one. .
[0021]
The gas flow rate integration circuit 4 integrates the gas flow rate value q obtained for each measurement period to obtain an integrated value Q of the gas flow rate (Q = Σq). The hardware and function of the gas flow rate integration circuit 4 may be the same as the conventional general one.
[0022]
The pulsation measuring circuit 6 measures the cycle Ts or phase of the gas pulsation based on the pressure value detected by the pressure sensor 7 at a frequency higher than the frequency at which the gas flow velocity v is measured.
[0023]
The start phase control circuit 5 provides a time interval Td between the measurement periods T, and sets the period or phase of the start timing of the plurality of measurement periods T as the pulsation period or phase measured by the pulsation measurement circuit 6. Are changed based on a predetermined regularity so as to be different.
[0024]
As the predetermined regularity used by the start phase control circuit 5, the start phase (start timing) of the measurement period T is, for example, 0.1 times, 0.2 times, 0.3 times,. It may be shifted every time in an arithmetic progression such as 9 times, then 0.9 times and then back again to 0.1 times, or the above may be repeated again, or 1/6 of the measurement period T The start timing of the measurement period T may be shifted so as not to synchronize with the pulsation phase, such as double, 2/6, 3/6,..., 5/6, and 6/6. In addition, they may be shifted randomly such as 1/6 times, 5/6 times, 6/6 times, 2/6 times, 5/6 times, and so on. Or, using the period of the gas pulsation period Ts as a reference, such as 1/12 times, 2/12 times, 3/12 times ... 12/12 times the measured gas pulsation period Ts, The start phase of the measurement period T may be shifted with 1/12 times the pulsation period Ts as one unit.
[0025]
A more detailed example of such a method of changing the start timing by the start phase control circuit 5 will be described with reference to FIG. Here, the start timing, that is, the start phase of the continuous measurement periods T1, T2, T3,..., Is appropriately combined with shifting to 0, 4π / 3, 2π / 3 [rad], respectively, compared to the pulsation phase. As an example, the case of temporal arrangement is given below. Note that the time lengths of the measurement periods T1, T2, and T3 are all set to 5Ts / 6 uniformly. Further, it is assumed that the time interval between the measurement periods adjacent in time is uniformly set to Ts / 2.
[0026]
As is apparent from FIG. 2, in each case of setting the measurement periods T1, T2, and T3, as shown in FIGS. It is not. That is, the area surrounded by the graph in the upper part of the t-axis is not equal to the area surrounded by the graph in the lower part. However, when the values in all cases of T1, T2, and T3 are integrated (summed), a correct average value is shown. That is, it can be seen that the area enclosed by the graph above the t-axis is equal to the area enclosed by the graph below. In this way, an error due to pulsation can be eliminated and a correct gas flow rate integrated value can be obtained.
[0027]
Here, as a comparative example, as shown in FIG. 3, the measurement periods T1, T2,... Are uniformly 5/6 times the pulsation period Ts, and the time between the plurality of measurement periods T. Considering the case where the intervals Td1, Td2,... Are uniformly Ts / 2, the measured value of the gas flow velocity v at T1 is smaller than the average value of pulsation, that is, the correct value, and is larger at T2. Thus, one cycle is constituted as a whole, but even if the values measured in the whole one cycle are integrated, an average value of pulsation, that is, a correct measured value is not obtained.
[0028]
In the above-described embodiment, an example in which an ultrasonic gas flow law measuring unit is used has been described. However, various other so-called estimation type gas flow rate measuring units may be used. Needless to say.
[0029]
In the above embodiment, the case where the flow rate measuring method of the present invention is applied to a gas meter that measures the gas flow rate has been described. However, the application of the present invention is not limited to this, for example, water or volatile oil-based liquids. The present invention is also applicable to various flow rate measuring devices such as a measuring device that measures the flow rate of a liquid such as fuel.
[0030]
【The invention's effect】
As described above, according to the present invention, it is possible to determine the period or phase of pulsation by providing a time interval between consecutive measurement periods and changing the start phase based on a predetermined regularity. If the error mixed in the measured value due to the pulsation is accumulated over multiple measurement periods, the errors complement each other and there is no pulsation. Thus, an accurate integrated value similar to the fluid flow rate value measured can be obtained. In addition, changing the start phase based on a predetermined regularity in this way can be performed with a small amount of power consumption, so that it is possible to achieve low power consumption of the driving power of the flow rate measuring device. There is also.
[0031]
In addition, no matter how the pulsation cycle or phase changes by actively changing the cycle or phase of the start timing of successive measurement periods every time so as not to synchronize with the cycle or phase of the fluid pulsation, When the error mixed in the measurement value due to the pulsation is accumulated over a plurality of measurement periods, the error is complementary to the excess and deficiency, and the fluid flow rate measured when no pulsation occurs An accurate integrated value similar to the value can be obtained.
[0032]
In addition, in a flow rate measuring device equipped with a pulsation measuring means for measuring a pulsation cycle or phase generated in a fluid, a fluid pressure pulsation cycle or phase is measured by using a pressure sensor capable of measuring with low power consumption. Is repeated at a frequency higher than a predetermined frequency based on the pressure value of the fluid, so that frequent information on pulsation can be obtained with a lower power consumption. In addition, it is possible to accurately grasp the period and phase of pulsation.
[Brief description of the drawings]
FIG. 1 is a diagram showing an outline of a configuration of a main part of a gas meter according to an embodiment of the present invention.
FIG. 2 is a diagram showing a more detailed example of a technique for changing the length of a time interval Td by a start phase control circuit.
FIG. 3 is a diagram schematically illustrating an example of a measurement result obtained by a conventional measurement method as a comparative example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Conduction path, 2a, 2b ... Ultrasonic transmission / reception apparatus, 2c ... Oscillation control circuit, 3 ... Gas flow velocity calculation circuit, 4 ... Gas flow rate integration circuit, ...・ Start phase control circuit, 6 ... Pulsation measurement circuit, 7 ... Pressure sensor

Claims (7)

Repeatedly measuring the flow rate or flow velocity value of the fluid flowing from the upstream side to the downstream side at a predetermined frequency per measurement period, multiple times, and integrating the values obtained for each measurement period In the flow velocity measurement method to
A flow velocity measurement method, wherein the start phase of the measurement period is changed based on a predetermined regularity. The period or phase of the pulsation generated in the fluid is measured, and the start phase of the measurement period is set to a predetermined regularity so that the period or phase of the start timing of the measurement period is different from the period or phase of the pulsation. The flow velocity measuring method according to claim 1, wherein the flow velocity is changed based on The flow velocity measuring method according to claim 1, wherein the period or phase of pulsation generated in the fluid is repeatedly measured at a frequency higher than the predetermined frequency based on the pressure value of the fluid. Repeatedly measuring the flow rate or flow velocity value of the fluid flowing from the upstream side to the downstream side at a predetermined frequency per measurement period, multiple times, and integrating the values obtained for each measurement period In the flow rate measuring device for obtaining the integrated flow rate value of the fluid,
A flow rate measuring device comprising start phase control means for changing the start phase of the measurement period based on a predetermined regularity. And further comprising pulsation measuring means for measuring a cycle or phase of pulsation generated in the fluid;
The flow velocity measuring device according to claim 4, wherein the start phase control means changes the cycle or phase of the start timing of the measurement period to be different from the cycle or phase of the pulsation. 6. The flow velocity measuring device according to claim 4, wherein the pulsation measuring unit measures a cycle or phase of the pulsation of the fluid at a frequency higher than the predetermined frequency based on a pressure value of the fluid. . The ultrasonic flow rate measuring means for propagating ultrasonic waves to the fluid and measuring the flow rate or flow velocity of the fluid based on the propagation time of the ultrasonic waves is provided. The flow velocity measuring device according to item 1.

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