JP2001281018A - Flow-rate measuring device and gas meter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flow-rate measuring device, such as a gas meter in which an overlap region is set and which eliminates drop in its measuring accuracy or the generation of the mixture of a noise or the like, even when a pulsating flow, a flow-rate change or the like is generated in a fluid to be measured. SOLUTION: A measurement control part 4 changes the upper limit and the lower limit of the overlap region, so that they become the upper limit or higher or the lower limit or lower than the pulsating flow or the flow-rate change, when the upper limit (indicated as Wh in the figure) of the pulsating flow or the flow-rate change is at the upper limit of lower than the practically measurable region of a low flow-rate sensor 1, and when the lower limit of the pulsating flow or the flow-rate change is at the lower limit or higher than the practically measurable region of a high flow-rate sensor 2. When it is detected by a pulsating flow and change detection part 3 that the pulsating flow, the flow-rate change or the like is not generated, a measurement control rule itself is changed over, in such a way that a flow rate is measured on the basis of the measurement control rule, which is set in advance so as to be executed inside the overlapped region.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a measuring device and a gas meter for measuring a flow rate or a flow velocity of a fluid, and more particularly, to a measuring device having a plurality of measuring devices having different measuring characteristics and performing a measuring operation of the fluid. The present invention relates to a measurement device and a gas meter set to be switched in accordance with a flow rate or a flow velocity.

[0002]

2. Description of the Related Art In a flow rate measuring device such as a gas meter for measuring a flow rate or a flow velocity of a fluid, for example, a flow rate of a gas to be measured is directly measured based on a change in the capacity of a blower, such as a membrane gas meter. For example, there has been proposed a method of measuring an instantaneous flow rate or an instantaneous flow rate of a fluid based on the measurement of the propagation time by transmitting an ultrasonic wave through a fluid and measuring the propagation time.

[0003] In particular, an indirect measurement type flow rate measuring device for measuring an instantaneous flow rate or an instantaneous flow velocity of a fluid generally has characteristics of high measurement accuracy and suitable for converting a measurement result into a data signal. Because of this characteristic, it has been proposed as a technique suitable for a microcomputer / gas meter or the like in which a so-called microcomputer (microcomputer) is incorporated and the measurement operation is controlled by the microcomputer. Examples of the type include a heat sensor system, an ultrasonic wave propagation system, and a fluidic system.

In such a flow rate measuring apparatus, generally, the flow rate and the flow rate of a fluid (hereinafter, these may be referred to as a flow rate. The flow rate value is generally obtained by multiplying the flow rate value by the cross-sectional area of the flow. In many cases, it is difficult to measure the entire area of the image with a sensor having one measurement characteristic (or output characteristic).

Therefore, two sensors, for example, a sensor for measuring a low flow rate (hereinafter referred to as a low flow rate sensor) and a sensor for measuring a high flow rate (hereinafter referred to as a high flow rate sensor) are provided as measuring means. Thus, an invention in which a plurality of measurement means are set to be switched such that measurement is performed by a low flow rate sensor in a low flow rate area and measurement is performed by a high flow rate sensor in a high flow rate area, for example, is a feature of the present inventors. JP-A-10-293054, JP-A-11-17389
No. 6 has been proposed.

However, when the low flow rate sensor and the high flow rate sensor are switched at a predetermined flow rate value as a boundary, when the flow rate that changes every moment frequently fluctuates at this one point, the so-called frequent sensor is used. May be switched.

Therefore, regarding the flow rate in a region where there is no practical difference in the measurement accuracy between the low flow rate sensor and the high flow rate sensor, if the history of the measured values from the past is in the increasing direction from the low flow rate, Controlling the switching of measurement means based on a hysteretic control rule that measures with a low flow sensor and measures with a high flow sensor when the history of measured values from the past is decreasing from high flow The technique to be performed is described in, for example, Japanese Patent Application Laid-Open
0648 publication and the like. According to the present invention, a flow area (hereinafter referred to as an overlap area) that is partially common to the low flow rate sensor and the high flow rate sensor is set, and a width is set for switching between the low flow rate sensor and the high flow rate sensor. With this arrangement, it is possible to eliminate the occurrence of such a phenomenon that the switching of a plurality of sensors frequently occurs as described above.

[0008]

However, for example, when a user uses a gas consuming device such as a gas heat pump, a low flow rate is set in spite of the above-mentioned overlap region being set. There is a problem that switching between the sensor and the high flow rate sensor is frequently performed, which may cause a decrease in measurement accuracy and a mixture of noise and the like. In addition, when frequent flow fluctuations such as undulations and fluctuations or flow velocity fluctuations occur in the gas flow, similarly to the case where pulsation occurs, the measurement accuracy may decrease and noise may be mixed. There is.

Such a phenomenon that occurs even though the overlap region is set is caused by pulsation when using a gas consuming device such as the above-described gas heat pump. The present inventors have confirmed that this is the case. Therefore, in order to eliminate the generation itself of such pulsation, the present inventors have studied various measures for rectifying the gas flow using a rectifying grid or a rectifying mesh.

[0010] However, in the measures using such rectifying means, even if it is possible to rectify the gas flow,
Since the gas pulsations are essentially short-period pressure waves, it has been found that it is essentially difficult or impossible to effectively eliminate such pulsations. In addition, a method of reducing the pulsation by continuously installing a large number of such rectifying meshes or the like, or eliminating a pulsation by attaching a small governor or the like to the gas meter may be considered, but the configuration of the entire gas meter is further increased. There is a problem in that the manufacturing cost is increased, and the production cost is further increased due to the addition of such a complicated configuration. In addition, by installing a large number of rectifying meshes and the like in the conduction path of the gas meter, the loss head of the gas flow is further increased, and a low flow rate sensor corresponding to a low flow rate is provided separately from the high flow rate sensor. However, a sensor corresponding to a further low flow rate region is required separately. Therefore, it is difficult to effectively eliminate the pulsation by the countermeasure using the rectifying means, and another problem may newly occur.

SUMMARY OF THE INVENTION The present invention has been made in view of such a problem, and an object of the present invention is to provide a flow rate measuring device such as a gas meter in which an overlap region is set, in which a pulsation occurs in a fluid such as a gas to be measured. It is possible to eliminate the occurrence of a decrease in measurement accuracy and the incorporation of noise and the like due to the occurrence of a flow rate fluctuation or frequent flow fluctuation.

[0012]

SUMMARY OF THE INVENTION A flow measuring device according to the present invention has a plurality of measuring means having different measuring characteristics for measuring a flow rate or a flow velocity of a fluid. Alternatively, in a flow measurement device that is set so that the measurement operation can be switched in accordance with the flow velocity, and at least two measurement units are set to be able to measure an overlap region of a partially common flow rate or flow velocity. The overlap region is set wider than the swing width so as to include the swing width of the pulsation generated in the fluid. Here, the setting of the overlap area may be fixedly determined in advance as a predetermined area, or, as described later,
The change may be made in response to the generated pulsation.

The upper limit of the overlap region may be higher than the upper limit of the pulsation vibration, and the lower limit of the overlap region may be lower than the lower limit of the pulsation vibration.

A pulsation detecting means for detecting an upper limit and a lower limit of the vibration of the pulsation; and an upper limit of the overlap region is set to be equal to or more than an upper limit of the vibration of the pulsation in accordance with the detected pulsation. May be further provided with a measurement control unit that sets the value of the pulsation to be equal to or less than the lower limit of the pulsation vibration.

[0015] Further, the apparatus may further include pulsation detecting means for detecting the presence or absence of pulsation, and the measurement control means may perform measurement without switching the measurement operation when pulsation occurs.

The flow rate measuring device according to the present invention has a plurality of measuring means having different measuring characteristics for measuring the flow rate or the flow rate of the fluid, and the plurality of measuring means correspond to the flow rate or the flow rate, respectively. In a flow measurement device that is set so that the measurement operation can be switched, and at least two measurement units are set to be able to measure an overlap region of a partially common flow rate or flow velocity, the overlap region is The width is set wider than the fluctuation width so as to include the fluctuation width of the flow rate fluctuation or the flow velocity fluctuation generated in the fluid.

The upper limit of the overlap region is set to be equal to or larger than the upper limit of the flow rate fluctuation or the flow velocity fluctuation.
The lower limit of the overlap region may be set to be equal to or less than the lower limit of the flow rate variation or the flow rate variation.

Further, a fluctuation detecting means for detecting an upper limit and a lower limit of the flow rate variation or the flow rate variation, and an upper limit of the overlap region is set to be equal to or more than the upper limit of the flow rate variation or the flow rate variation in response to the detected flow rate variation or the flow rate variation. In addition, a measurement control unit that sets the lower limit of the overlap region to the lower limit of the flow rate variation or the flow rate variation may be further provided.

Further, the apparatus further comprises a fluctuation detecting means for detecting the occurrence of the flow rate fluctuation or the flow velocity fluctuation, and the measurement control means performs the measurement without switching the measuring operation when the flow rate fluctuation or the flow velocity fluctuation occurs. There may be.

The flow rate measuring apparatus according to the present invention has a plurality of measuring means having different measuring characteristics for measuring the flow rate or the flow rate of the fluid, and the plurality of measuring means correspond to the flow rate or the flow rate, respectively. In a flow measurement device which is set to be able to switch its measurement operation and at least two measurement means are set so as to be able to measure an overlap region of a partially common flow or flow velocity, the flow is generated in a fluid. Pulsation detecting means for detecting the upper and lower limits of the pulsation vibration, and measurement control means for switching the measurement operation of the measurement means, the measurement control means, the pulsation vibration in an area below the lower limit of the overlap area The flow rate or the flow rate, if it is vibrating above and below the lower limit of the overlap area. If the pulsation is oscillating within the overlap region, that is, between the lower limit and the upper limit, the flow rate of the overlap region is measured. Alternatively, measurement is performed by a preset measuring means to perform measurement corresponding to the flow velocity, and when the pulsation is oscillating in an area above the upper limit of the overlap area and the When vibrating vertically, the measuring unit is controlled so that measurement corresponding to such a flow rate or flow velocity is performed by a preset high flow rate measuring unit. Is what you do.

The flow rate measuring device according to the present invention has a plurality of measuring means having different measuring characteristics for measuring the flow rate or the flow rate of the fluid, and the plurality of measuring means correspond to the flow rate or the flow rate, respectively. In a flow measurement device which is set to be able to switch its measurement operation and at least two measurement means are set so as to be able to measure an overlap region of a partially common flow or flow velocity, the flow is generated in a fluid. Fluctuation detection means for detecting the upper and lower limits of the flow rate fluctuation or flow velocity fluctuation, and a measurement control means for switching the measurement operation of the measurement means, wherein the flow rate fluctuation or flow velocity fluctuation is less than the lower limit of the overlap region If it fluctuates in the lower region and fluctuates above and below the lower limit, such a flow rate or When the measurement corresponding to the flow velocity is performed by a preset measuring means, and the flow rate fluctuation or the flow velocity fluctuation fluctuates between the lower limit and the upper limit of the overlap region, the flow rate or the flow rate The measurement corresponding to the flow velocity is performed by the measurement means set in advance, and when the flow rate fluctuation or the flow velocity fluctuation fluctuates in the region above the upper limit of the overlap region and the upper limit of the overlap region is determined. If it fluctuates across the upper and lower sides of the sandwich, the operation of the measuring means is performed so that the measurement corresponding to the flow rate or the flow velocity is performed by the measuring means set in advance. To control.

A gas meter according to the present invention uses the flow rate measuring device according to any one of the above, wherein the fluid is a gas. That is, in the flow rate measuring device according to the present invention, the width between the upper limit and the lower limit of the region that can be partially measured by the two measuring means, that is, the overlap region, is set wider than the pulsation swing width. Thus, the pulsation fluctuation is included in the overlap region. As a result, the pulsation does not deviate from the overlap region, so that even if pulsation occurs, the on / off of a plurality of measuring means such as the low flow rate sensor and the high flow rate sensor does not frequently switch. As a result, noise and errors do not occur in the measurement result.

The pulsation detecting means detects the upper limit and the lower limit of the vibration of the pulsation, and in response to the detected pulsation, the measurement control means sets the above-mentioned overlap region, ie, the upper limit of the overlap region, to the upper limit of the vibration of the pulsation. In addition to the above, the lower limit of the overlap region is set to be equal to or less than the lower limit of the pulsation vibration. As a result, the pulsation does not deviate from the overlap region, so that even if pulsation occurs, frequent switching of on / off by a plurality of measuring means such as a low flow sensor and a high flow sensor may occur. There is no. As a result, noise, error, and the like do not occur in the measurement result.

Here, the measurement in the overlap region may be performed based on a hysteretic control rule as conventionally proposed, or two types of sensors, a low flow sensor and a high flow sensor, may be used. Of a plurality of sensors such as sensors, one having higher measurement accuracy in the overlap region may be used. Alternatively, it is also possible to take an average value of the values measured by these sensors. In any case, in the flow rate measuring device according to the present invention, since the overlap region is set to be broad so as to include the pulsation, even if any pulsation occurs, a plurality of measurement means are included in the overlap region. No on / off switching occurs. Therefore, since there is no restriction such as selection based on a hysteretic control rule, as a measurement unit used for measurement in the overlap region, a measurement unit with higher measurement accuracy is selected and used. , Can be arbitrarily selected.

The presence or absence of pulsation is detected by pulsation detection means, and when pulsation is detected, measurement is performed without switching the measurement operation. Accordingly, frequent switching of on / off of a plurality of measurement units such as the low flow rate sensor and the high flow rate sensor does not occur. As a result, noise, error, and the like do not occur in the measurement result.

In the flow rate measuring device according to the present invention, the upper limit and the lower limit of the vibration of the pulsation generated in the fluid are detected by the pulsation detecting means. When the detected pulsation oscillates above and below the lower limit of the overlap region, measurement is performed by such a low flow rate measurement unit. When the pulsation is oscillating in the overlap region above the upper limit of the overlap region, the measurement is performed by such a high flow rate measurement unit. Thus, even when the pulsation fluctuates at the upper limit or the lower limit of the overlap area, frequent switching of a plurality of measurement units such as a low flow sensor and a high flow sensor does not occur. As a result, noise, error, and the like do not occur in the measurement result.

In the flow rate measuring device according to the present invention, in addition to the above-described pulsation, when a so-called swelling or fluctuation occurs in the flow rate and flow velocity of the fluid, the low flow rate sensor is used similarly to the above. Frequent on / off switching of a plurality of measuring means such as a high flow rate sensor does not occur.

The present invention is particularly suitable for a flow rate measuring device such as a gas meter for city gas. However, the present invention is not limited thereto. In addition, for example, a gas meter for propane gas, a flow meter for gas obtained by vaporizing automotive fuel or other various fuels, a flow meter for various gases used in a chemical plant, etc. It is also applicable to such as. Alternatively, the present invention can be applied to a water meter that measures the flow rate of a liquid such as tap water.

[0029]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram showing a schematic configuration of a gas meter according to an embodiment of the present invention. The gas meter includes a low flow sensor and a high flow sensor 2 (measuring means), and a pulsation / fluctuation detection unit 3 for detecting pulsation and flow fluctuation.
(Pulsation detection means and fluctuation detection means), a measurement control unit 4 (measurement control means) for controlling the measurement operation of the low flow sensor 1 and the high flow sensor 2, a flow value calculation unit 5 (flow value calculation means), The flow rate integrating section 6 (flow rate integrating means) is provided in the main part. In addition, in addition to this, a shutoff valve,
Needless to say, various devices commonly used as a gas meter, such as a device for detecting the occurrence of micro leakage and a return switch for executing shut-off return (all not shown), are provided. Since various devices and the like have little direct relationship with the main configuration of the present invention, their description is omitted.

More specifically, the low flow rate sensor 1 and the high flow rate sensor 2 are arranged in a conducting path 7 for conducting gas, and measure the gas flow rate based on a temperature that changes according to the gas flow rate. Things. The low flow rate sensor 1 and the high flow rate sensor 2 have different measurement sensitivity characteristics or output characteristics, and their measurable flow rate value regions are partially common to each other, for example, as shown in FIG. Area, ie, overlap area (L0-H0)
Is set to exist.

As the low flow rate sensor 1 and the high flow rate sensor 2, a heat generating portion (not shown) is provided on the upstream side, and is arranged at predetermined intervals along the gas flow.
One is to measure the temperature difference measured by a set of temperature sensors, and to measure the gas flow rate based on the temperature difference, or to keep the amount of heat generated by a heating unit (not shown) provided on the upstream side constant. It measures the amount of power that needs to be supplied to the heat generating part to keep it, and measures the flow rate of gas based on the amount of power, or the sensor itself is set to keep the temperature constant In addition, a device that measures the amount of power required to keep the temperature constant and measures the gas flow rate based on the amount of power can be suitably used.

It is needless to say that the low flow sensor 1 preferably has a measurement sensitivity characteristic capable of performing accurate measurement in a low flow region, but it is desirable that the upper limit of the measurable region be as high as possible. . Needless to say, it is desirable that the high flow rate sensor 2 has a measurement sensitivity characteristic that allows accurate measurement in a high flow rate region, but it is desirable that the lower limit of the measurable region be as low as possible.

However, in practice, the upper limit of the measurable region of the low flow sensor 1 and the lower limit of the measurable region of the high flow sensor 2 need to satisfy, for example, the accuracy required for a commercial measuring instrument. Therefore, the upper limit of the overlap region is defined by the upper limit of the measurable region of the low flow sensor 1, and the lower limit of the overlap region is defined by the lower limit of the measurable region of the high flow sensor 2. A sensor that can measure the flow rate as accurately as possible within such a measurement limit is desirable.

From such a viewpoint, the overlap region may be fixedly set in advance to the upper limit of the measurable region of the low flow sensor 1 and the lower limit of the measurable region of the high flow sensor 2. However, actually, the sensors used as the low flow rate sensor 1 and the high flow rate sensor 2 are not limited to those capable of performing highly accurate measurement over the wide flow rate range as described above. In recent years, with the diversification and diversification of gas combustion equipment, the flow rate range of the measurement target has tended to increase over a wide range, and high-precision measurement has been performed over such a wide flow rate range. It is not easy to realize the low flow rate sensor 1 and the high flow rate sensor 2 that can perform the above. In addition, the use of such a sensor capable of high-accuracy measurement has a disadvantage that the apparatus becomes complicated and costs are increased. In addition, when pulsation occurs due to too high accuracy, it is picked up as a measurement error or noise, and the accuracy of the measured value is rather reduced. Because of this,
In view of a higher safety factor, it is desirable to set the overlap area in advance in a smaller area than the measurable area. Only when the occurrence of pulsation or flow rate fluctuation is detected, it is desirable to enlarge or change the overlap area in accordance with the fluctuation width of the pulsation or the like by a method described later.

The pulsation / fluctuation detection unit 3 determines whether pulsation or other frequent flow fluctuations occur in the gas at that time based on the measurement data output from the low flow sensor 1 and the high flow sensor 2. It is to determine whether or not. More specifically, the detection method of the pulsation or fluctuation is, for example, sampling measurement data of a predetermined number of times in the past, calculating a standard deviation thereof, and when the standard deviation is equal to or more than a predetermined value, pulsation or fluctuation. It may be determined that a flow rate fluctuation or the like has occurred. Further, the maximum value and the minimum value of the measurement data for the predetermined number of times of measurement in the past are obtained, respectively, and when the difference between the maximum value and the minimum value is equal to or more than a predetermined value, pulsation, flow rate fluctuation, and the like occur. The maximum value may be detected as the upper limit of the pulsation or the flow rate fluctuation, and the minimum value may be detected as the lower limit of the pulsation or the flow rate fluctuation. In addition, as a method of detecting pulsation or flow rate fluctuation by the pulsation / fluctuation detection unit 3, for example, a pressure sensor is used to detect that a pressure fluctuation has occurred in the gas, and based on this, It is also possible to detect pulsation, flow fluctuation, and the like.

The measurement controller 4 controls the measurement of the gas flow rate by the low flow rate sensor 1 and the high flow rate sensor 2. More specifically, the flow rate value calculated by the flow rate calculation unit 5 based on the measurement data output by the low flow rate sensor 1 or the high flow rate sensor 2 is within the measurement area of the low flow rate sensor 1, and the pulsation or the like is When it is determined by the pulsation / fluctuation detection unit 3 that no flow has occurred, the flow value calculation unit 5 calculates the flow value at that time using only the measurement data output from the low flow sensor 1. Then, the measurement control at that time is performed.

Further, the flow rate value calculated by the flow rate calculation unit 5 based on the measurement data output by the low flow rate sensor 1 or the high flow rate sensor 2 is within the high flow rate range,
The pulsation / fluctuation detection unit 3 indicates that no pulsation has occurred.
When the determination is made, measurement control is performed so that the flow value calculation unit 5 calculates the flow value at that time using only the measurement data from the high flow sensor 2.

The flow rate value calculated by the flow rate calculation unit 5 based on the measurement data output from the low flow rate sensor 1 or the high flow rate sensor 2 is set in advance in consideration of the high safety factor as described above. If the pulsation / fluctuation detection unit 3 detects that the pulsation / fluctuation fluctuation or the like does not occur within the overlap region where the pulsation or the flow rate fluctuation has occurred, the pulsation / fluctuation detection unit 3 is set in advance so as to be executed within the overlap region. The flow rate is measured based on the following measurement control rules.

That is, as a measurement control rule in the overlap region, one of the two flow sensors is selected based on a hysteresis-based measurement control rule as conventionally proposed, and measurement is performed. Or an average value of the measurement data of both sensors. By taking the average value in this way, even if, for example, the measurement data of the high-precision low flow sensor 1 contains a lot of errors and noise due to pulsation, the data is measured by the high flow sensor 2 By averaging, it is possible to obtain an advantage that a relative influence on a true value of an error or noise can be reduced. Alternatively, a sensor capable of performing more accurate measurement may be selected in accordance with a flow rate region in which pulsation, flow rate variation, and the like occur. In any case, at this time, the pulsation and the fluctuation of the flow rate fluctuation are included without deviating from the overlap region. Therefore, as a measurement control rule in the overlap region, sensor switching as in the related art frequently occurs. The present invention is not limited to hysteretic control or the like for avoiding a phenomenon that occurs, and any of the above methods can be applied.

When the pulsation / fluctuation detection unit 3 detects that a pulsation or a flow rate fluctuation has occurred,
The upper and lower limits of the overlap area are changed in accordance with the upper and lower limits of the pulsation and flow rate fluctuation, and the following measurement control rules are determined in advance so as to be executed in relation to the overlap area. The flow rate is measured based on.

That is, as shown in FIG. 3, the upper limit of pulsation or flow fluctuation (indicated by Wh in FIG. 3) is the upper limit of the practically measurable area of the low flow sensor 1 (indicated by Ph in FIG. 3). When the lower limit of the pulsation and the flow rate fluctuation (indicated by Wl in FIG. 3) is equal to or larger than the lower limit of the practically measurable area of the high flow rate sensor 2 (indicated by Pl in FIG. 3), The upper limit (shown as H in FIGS. 2, 3 and 4) and the lower limit (shown as L in FIGS. 2, 3 and 4) of the overlap region are:
The pulsation and the flow rate are changed so that they are not less than the upper limit and not more than the lower limit. For example, the upper limit of the overlap region is changed to 1.2 times the upper limit of the flow rate fluctuation, and the lower limit is changed to 0.8 times the lower limit of the flow rate fluctuation. This is because, in the state where pulsation is occurring, the influence of noise and errors caused by pulsation is greater than the measurement accuracy of the two sensors 1 and 2, which has a greater adverse effect on the measurement result. Even if the measurement accuracy of the two sensors 1 and 2 falls within the practical range, it is more effective to prevent the occurrence of a phenomenon in which the two sensors 1 and 2 are frequently switched due to pulsation. This is because it can be secured. It is desirable to set the upper and lower limits of the overlap region with a margin so that even if fluctuations occur in the pulsation and the flow rate fluctuation, the fluctuation width does not deviate and is included in the overlap region. . After setting as described above, the flow rate is measured based on the measurement control rule in the overlap region in the same manner as in the case where there is no pulsation or flow rate fluctuation. That is, the flow rate is measured in the overlap region at that time based on one of a hysteretic measurement control rule, a measurement control rule of taking an average value of measurement data of both sensors, and the like.

When the upper limit of the pulsation or the flow rate fluctuation exceeds the upper limit of the practical measurable area of the low flow sensor 1 in the pulsation generation state, or the lower limit of the pulsation or the flow rate fluctuation is high in the pulsation generation state. If it is less than the lower limit of the practical measurable area of the flow sensor 2, first, the upper limit of the overlap area is set as the upper limit of the measurable area of the low flow sensor 1,
The lower limit of the overlap area is changed to the lower limit of the measurable area of the high flow sensor 2. That is, the overlap region is maximized so as to cover the entire width of the region that can be measured practically in common by the high and low sensors 1 and 2.

More specifically, as shown in FIG. 4A, when the lower limit of the pulsation or the flow rate fluctuation is lower than the lower limit of the overlap region enlarged to the maximum for practical use, in other words, When the fluctuation of the pulsation or the flow fluctuation fluctuates above and below the lower limit of the overlap region, only the measurement data output from the low flow sensor 1 is used.
As the flow value calculation unit 5 calculates the flow value at that time,
Perform measurement control.

Further, as shown in FIG. 4B, when the upper limit of the pulsation or the flow rate fluctuation is higher than the upper limit of the overlap region enlarged to the maximum for practical use, in other words, the pulsation or the flow rate fluctuation In the case where the fluctuation is above and below the upper limit of the overlap region, the flow value calculation unit 5 calculates the flow value at that time using only the measurement data output from the high flow sensor 2. Measurement control is performed as described above.

Also, as shown in FIG. 4C, when the pulsation and the flow rate fluctuation are included in the overlap region enlarged to the maximum practically, the same as in the case shown in FIG. Then, the flow rate is measured based on the measurement control rule in the overlap region. That is, the flow rate is measured in the overlap region at that time based on a hysteretic measurement control rule, a measurement control rule of taking an average value of measurement data of both sensors, and the like.

As shown in FIG. 5 (A), when the region where the pulsation or flow fluctuation occurs becomes smaller than the previously set overlap region, the low flow sensor 1
Perform flow measurement only with Conversely, as shown in FIG. 5 (B), when the overlap area is exceeded, the flow rate is measured only by the high flow rate sensor 2.

The operation of the flow value calculating section 5 is controlled by the above-mentioned measurement control section 4, and the flow rate value v at that time is calculated based on the measurement data output from the low flow rate sensor 1 and the high flow rate sensor 2. Then, a flow coefficient k corresponding to the flow velocity value v is obtained, and an operation of multiplying the obtained flow coefficient k is performed to obtain an instantaneous flow value Q of the gas at the measurement duty at that time.

The flow rate integrating section 6 integrates the flow rate measured values Q obtained by the flow rate calculating section 5. That is, when the flow rate calculating section 5 newly calculates the flow rate measurement value Q and transmits the data, the flow rate integrating section 6 stores the data of the new flow rate measurement value Q until then. To the integrated flow rate 流量 Q. In this way, when the new flow measurement value Q is transmitted, the flow value integrating unit 6
The flow integrated value ΣQ is sequentially incremented.

The flow rate calculating section 5 and the flow value accumulating section 6 described above may be conventional hardware and control logic.

Next, an outline of the measuring operation by the gas meter will be described.

FIG. 6 is a flow chart showing the outline of the measurement operation mainly on the pulsation determination process by the gas meter. The pulsation / fluctuation detection unit 3 determines whether pulsation or frequent flow fluctuation has occurred (S
1). At this time, if it is not detected that pulsation or frequent flow fluctuation has occurred (N in S1), the overlap area is set to a predetermined area in consideration of the safety factor (S2). Then, a flow measurement routine as described later is executed (S3). Alternatively, at this time, if it is detected that pulsation or frequent flow fluctuation has occurred (S
1) Y), the setting of the overlap region is changed in accordance with the upper and lower limits of the pulsation and the fluctuation of the flow rate fluctuation (S).
4). Then, a flow rate measurement routine (S
5) is executed.

FIGS. 7, 8 and 9 are flowcharts showing the outline of the flow rate measurement routine. In the flow rate measurement routine, when pulsation or flow rate fluctuation occurs (FIGS. 7 and 8)
A different operation flow is executed depending on whether or not the error has occurred (FIG. 9).

When it is detected that pulsation or flow fluctuation has occurred (Y in S1 of FIG. 6), first, as shown in FIG. 7, the upper and lower limits of the pulsation or flow fluctuation are detected (FIG. 7). S21). The entire fluctuation of the pulsation and the flow rate fluctuation (that is, both the upper limit and the lower limit thereof)
If it is in the area below the lower limit of the practically measurable area (Y in S22), the flow rate is measured based only on the output of the low flow rate sensor 1 (S24). At this time, the overlap area does not need to be changed (S23).

When the lower limit and the upper limit of the pulsation and the flow rate fluctuation are above and below the lower limit of the practically measurable area of the high flow rate sensor 2 (Y in S25), only the output of the low flow rate sensor 1 is used. To measure the flow rate (S27). At this time, the lower limit of the overlap area is set to the lower limit of the practically measurable area of the high flow rate sensor 2, and the upper limit of the overlap area is set to the upper limit of the practical measurable area of the low flow rate sensor 1 (S26). .

When the lower limit and the upper limit of the pulsation and the flow rate fluctuation are within the range between the lower limit of the practically measurable area of the high flow rate sensor 2 and the upper limit of the practically measurable area of the low flow rate sensor 1. (Y in S28), the lower limit and the upper limit of the overlap region are set to the lower limit and the upper limit of the pulsation and the flow rate fluctuation, respectively (S29). Then, the flow rate at that time is measured based on the measurement control rule in the overlap region as described above (S30).

If the lower and upper limits of the pulsation and the flow rate fluctuation are above and below the upper limit of the practically measurable area of the low flow rate sensor 1 (Y in S31), as shown in FIG.
The flow rate at that time is measured based only on the output of the high flow rate sensor 2 (S33). At this time, the upper limit of the overlap area is set to the upper limit of the practically measurable area of the high flow rate sensor 2, and the lower limit of the overlap area is set to the lower limit of the practical measurable area of the low flow rate sensor 1 (S3).
2).

If the entire pulsation or the fluctuation of the flow rate fluctuation is in the area above the upper limit of the practically measurable area of the low flow rate sensor 1 (N in S31), the output is determined based only on the output of the high flow rate sensor 2. The flow rate is measured (S35). At this time, the setting of the overlap area does not need to be changed (S3
4).

On the other hand, when it is determined that no pulsation or flow fluctuation has occurred (N in S1 in FIG. 6), first, as shown in FIG. A predetermined overlap area is set (S41).

If the flow rate at that time is in a region below the lower limit of the predetermined overlap region (S4).
2), flow measurement is performed based only on the output of the low flow sensor 1 (S43).

If the flow rate is within the predetermined overlap area (Y in S44), the flow rate is measured based on the same rule as the flow rate measurement based on the measurement control rule in the overlap area (step S44). S45). That is, the flow rate is measured in the overlap region at that time based on a hysteretic measurement control rule, a measurement control rule of taking an average value of measurement data of both sensors, and the like.

When the flow rate is in the area above the upper limit of the predetermined overlap area (N in S44), the flow rate is measured only based on the output of the high flow rate sensor 2 (S4).
5). Here, in each of the above cases, as a method of obtaining information of the flow rate used for performing the determination of the flow rate region and the detection of the pulsation, for example, the flow rate value of the measurement result of a predetermined number of times in the past, such as the past 10 times, is used. It is preferable to calculate an average value. In this case, strictly speaking, there is a slight control delay in the control operation of the flow rate measurement, which is about the time required to obtain the measured value for at most several times and the time required to calculate the average value thereof. Therefore, there is no practical problem at all.

In the above embodiment, the case where the technology of the flow rate measuring device of the present invention is applied to a gas meter for city gas has been described, but the application of the present invention is not limited to such a gas meter. Needless to say. In addition, the present invention can be applied to, for example, a gas meter of propane gas, a flow rate meter for gas obtained by vaporizing fuel for automobiles and other various fuels, a flow meter for various gases used in a chemical plant and the like. Alternatively, the present invention can be applied to a water meter that measures the flow rate of a liquid such as tap water. For example, when the water flow supplied to the user side through a water meter has frequent fluctuations or the like, the technology of the present invention is effective also for eliminating measurement errors and noise caused by such fluctuations. .

[0064]

As described above, claims 1 to 4
According to the flow rate measuring device according to any one of the above, the flow rate measuring device according to the ninth aspect, or the gas meter according to the eleventh aspect, even when pulsation occurs in a fluid such as a gas to be measured, Thus, it is possible to eliminate the decrease in the measurement accuracy and the occurrence of mixing of noise and the like.

According to the flow rate measuring device as set forth in any one of claims 5 to 10 or the gas meter as set forth in claim 11, when frequent flow rate fluctuations or flow rate fluctuations occur in a fluid such as a gas to be measured. However, there is an effect that it is possible to eliminate the decrease in measurement accuracy and the occurrence of mixing of noise and the like due to the measurement.

Further, according to the flow rate measuring device according to the third or ninth aspect or the gas meter according to the eleventh aspect, the upper and lower limits of the swing width of the pulsating flow generated in the fluid are detected, and two measuring means are provided. By setting the overlap region to be wider than the pulsation swing width and completely encompassing it, no matter how the swing width of the generated pulsating flow or its upper and lower limits changes, It is possible to eliminate the decrease in measurement accuracy and the occurrence of noise and the like due to the pulsation.

According to the flow rate measuring device described in claim 7 or 10 or the gas meter described in claim 11, the upper limit and the lower limit of the fluctuation of the flow rate or the fluctuation of the flow rate generated in the fluid are detected, and at least By changing the overlap region of the two measuring means to be wider than the fluctuation range of the flow rate fluctuation or the flow rate fluctuation so as to completely cover the fluctuation range, the flow fluctuation such as waviness or fluctuation generated in the fluid or Regardless of how the upper and lower limits of the flow velocity fluctuations are changed, there is an effect that it is possible to eliminate the deterioration of the measurement accuracy and the occurrence of noise and the like caused by the flow rate fluctuations.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a schematic configuration of a gas meter according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating an example of measurement sensitivity characteristics of a low flow sensor and a high flow sensor.

FIG. 3 is a diagram illustrating an example of a state in which a pulsation or a fluctuation of a flow rate variation falls within an overlap region.

FIG. 4 is a diagram illustrating a relationship between a pulsation or a flow rate fluctuation and a maximum overlap region.

FIG. 5 is a diagram illustrating a relationship between a pulsation or a flow rate fluctuation and a maximum overlap region.

FIG. 6 is a flowchart illustrating an outline of a measurement operation centering on a process of determining a pulsation.

FIG. 7 is a flowchart illustrating an outline of an operation when it is detected that a pulsation or a flow rate fluctuation has occurred.

FIG. 8 is a flowchart illustrating an outline of an operation when it is detected that a pulsation or a flow rate fluctuation has occurred.

FIG. 9 is a flowchart illustrating an outline of an operation when it is detected that no pulsation or flow fluctuation has occurred.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Low flow sensor, 2 ... High flow sensor, 3 ... Pulsation / fluctuation detection part, 4 ... Measurement control part, 5 ... Flow value calculation part, 6 ... Flow value integration part

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Takeshi Ken 1-5-20 Kaigan, Minato-ku, Tokyo Tokyo Gas Co., Ltd. F-term (reference) 2F030 CA10 CB02 CB09 CC13 CD13 CE02 CE04 CF05 CF11

Claims (11)

[Claims] A plurality of measuring means having different measurement characteristics for measuring a flow rate or a flow rate of a fluid are provided, and the plurality of measuring means can switch a measuring operation in accordance with the flow rate or the flow rate, respectively. Is set as
And a flow measuring device in which at least two measuring means are set so as to be able to measure an overlap region of a partially common flow rate or flow velocity, wherein the overlap region includes a fluctuation width of a pulsation generated in the fluid. The flow measurement device is set to be wider than the swing width. 2. The method according to claim 1, wherein an upper limit of the overlap region is set to be equal to or more than an upper limit of the pulsation vibration, and a lower limit of the overlap region is set to be equal to or less than the lower limit of the pulsation vibration. The flow measurement device according to claim 1. 3. A pulsation detecting means for detecting an upper limit and a lower limit of the vibration of the pulsation, and an upper limit of the overlap region is set to be equal to or more than an upper limit of the vibration of the pulsation in response to the detected pulsation. The flow measurement device according to claim 1, further comprising a measurement control unit that sets a lower limit of the overlap region to a lower limit of the vibration of the pulsation. 4. A pulsation detection means for detecting whether or not the pulsation has occurred, and a measurement control means for controlling the measurement means so as to perform the measurement without switching the measurement operation when the pulsation occurs. The flow rate measuring device according to claim 1, further comprising: 5. A plurality of measurement means having different measurement characteristics for measuring a flow rate or a flow rate of a fluid, and the plurality of measurement means can switch a measurement operation in accordance with the flow rate or the flow rate, respectively. Is set as
And a flow measurement device in which at least two measurement means are set so as to be able to measure an overlap area of a partially common flow rate or flow velocity, wherein the overlap area has a flow rate variation or a flow rate variation generated in the fluid. A flow rate measuring device characterized by being set wider than the run-out width so as to include the run-out width. 6. An upper limit of the overlap region is set to be equal to or more than the upper limit of the flow rate variation or the flow rate variation, and a lower limit of the overlap area is set to be equal to or less than the lower limit of the flow rate variation or the flow rate variation. The flow rate measuring device according to claim 5, characterized in that: 7. A fluctuation detecting means for detecting an upper limit and a lower limit of the flow rate variation or the flow rate variation; and an upper limit of the overlap region in response to the detected flow rate variation or the flow rate variation. 6. The flow rate measuring device according to claim 5, further comprising: a measurement control unit that sets the lower limit of the overlap region to a value equal to or less than the lower limit of the flow rate variation or the flow rate variation. 8. A fluctuation detecting means for detecting the occurrence of the flow rate fluctuation or the flow velocity fluctuation, and the measuring means for performing the measurement without switching the measuring operation when the flow rate fluctuation or the flow velocity fluctuation occurs. 6. The flow measuring device according to claim 5, further comprising a measurement control unit for controlling the flow rate. 9. A plurality of measurement means having different measurement characteristics for measuring a flow rate or a flow rate of a fluid, and the plurality of measurement means switch the measurement operation in accordance with the flow rate or the flow rate, respectively. In a flow measurement device that is set so as to be able to measure, and at least two measurement means are set to be able to measure an overlap region of a partially common flow or flow velocity, A pulsation detection unit that detects an upper limit and a lower limit, and a measurement control unit that switches a measurement operation of the measurement unit, further comprising: a measurement control unit, wherein the pulsation vibrates in a region below a lower limit of the overlap region. If it is, and if it vibrates straddling the upper and lower sides of the lower limit of the overlap region, it corresponds to the flow rate or flow velocity below the lower limit. When the pulsation is oscillating between the lower limit and the upper limit of the overlap area, the flow rate in the overlap area is measured. Alternatively, the measurement is performed by a measuring unit that is set in advance to perform the measurement corresponding to the flow velocity, and when the pulsation is oscillating in an area above the upper limit of the overlap area and the upper limit of the overlap area When vibrating straddling the upper and lower sides of the measuring means, the measuring means is configured to perform the measurement by a measuring means which is set in advance to perform the measurement corresponding to the flow rate or the flow velocity on the measuring means. A flow rate measuring device for controlling the flow rate. 10. A plurality of measuring means having different measuring characteristics for measuring a flow rate or a flow rate of a fluid, and the plurality of measuring means switch the measuring operation corresponding to the flow rate or the flow rate, respectively. A flow rate measuring device, wherein at least two measuring means are set to be able to measure an overlap region of a partially common flow rate or flow rate, wherein a flow rate fluctuation or flow rate generated in the fluid Fluctuation detecting means for detecting the upper and lower limits of the fluctuation vibration, and a measurement control means for switching the measurement operation of the measuring means, further, the measurement control means, the flow rate fluctuation or flow velocity fluctuation of the overlap region When vibrating in a region below the lower limit, and when vibrating over the upper and lower sides of the lower limit of the overlap region. In this case, the measurement is performed by a measuring means that is set in advance to perform the measurement corresponding to the lower flow rate or flow velocity, and the flow rate fluctuation or the flow rate fluctuation is between the lower limit and the upper limit of the overlap region. In the case of oscillating within the range, the measurement is performed by a measuring unit that is set in advance to perform the measurement corresponding to the flow rate or the flow velocity in the overlap region, and the flow rate variation or the flow rate variation is caused by the overlap. When oscillating in an area above the upper limit of the area and when oscillating vertically above and below the upper limit of the overlap area, measurement corresponding to the flow rate or flow velocity above the area is performed. A flow meter for controlling the measuring means so as to perform the measurement by a measuring means which is set in advance. Apparatus. 11. A gas meter using the flow measurement device according to claim 1, wherein the fluid is a gas.