JP2000009501A - Flowmeter and flow rate measuring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the precision of a presumption type flowmeter by reducing the error of a flow rate integrated value. SOLUTION: A flow rate measured value obtained by a flow rate measurement part 1 is stored in a flowmeter measured value storage part 14 of a process part 12, and a flow rate variation decision part 15 judges whether or not the difference between a last flowmeter measured value and a current flow rate measured value exceeds a set range value. A flow rate integration part 16 does not perform integration based upon the current flowmeter measured value when the flow rate variation exceeds the set range value and finds as a flow rate a passage quantity, based upon a flow rate measured value at the top of a flow rate integrating process and the flowmeter measured value at the last measurement time when the variation converges into the specific range, and integrates the passage quantity based upon the flowmeter measured value to the found flow rate to obtain a flow rate integrated value QS.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow meter for measuring a flow rate used in an electronic gas meter or the like, and more particularly, to an inferential flow meter for intermittently measuring a flow rate in a flow path and calculating an integrated flow rate. And a flow measurement method.

[0002]

2. Description of the Related Art Conventionally, as a flow meter used for flow measurement of an electronic gas meter or the like, an inferential flow meter such as an ultrasonic type, a fluidic type, a flow sensor type, etc. has been proposed and used. .

[0003] For example, a flow sensor type flow meter has a heater and a temperature sensor in a flow path as flow rate measuring means, and a temperature change in a temperature sensor located near a flow of a fluid or an upstream side of the heater. It is configured to include means for measuring a temperature difference from the downstream side or the like and calculating an instantaneous flow rate at predetermined time intervals. A configuration example of a flow sensor type flow meter is disclosed in Japanese Patent Publication No. 7-3354. Also, the ultrasonic type flow meter has two acoustic transducers operating at an ultrasonic frequency which are arranged at a fixed distance in the flow path as flow measuring means, and the flow rate of fluid between these transducers is controlled. The apparatus is provided with means for measuring a difference in ultrasonic propagation time between the forward direction and the reverse direction, and calculating an instantaneous flow rate at predetermined time intervals. A configuration example of an ultrasonic type flow meter is disclosed in Japanese Patent Application Laid-Open No. 9-21667 and the like.

[0004] In these speculative flow meters, the flow rate is calculated by multiplying the instantaneous flow rate measured by the flow rate measuring means by a sampling interval, which is a measurement time interval, to calculate the flow rate in that period, and integrating the total flow rate. A method is used.

[0005]

In the above-mentioned inferential flow meter, when used as a gas meter, the use of gas is stopped when the gas flow rate is gradually increasing or decreasing or immediately after measuring the instantaneous flow rate. In some cases, for example, there is a difference between the integrated flow rate value and the actual flow rate. Although the instantaneous difference at this time is small, since the integrated value is accumulated, there is a problem that the error is also accumulated and increased.

FIG. 6 shows a difference between the actual flow rate and the integrated flow rate when the flow rate is increasing. In the conventional accumulation method,
The instantaneous flow rate is Q1, Q at every sampling time of n seconds.
2 and Q3, the flow rate integrated value QS [L /
h (liter / hour)] is: QS = (Q1 x n / 3600) + (Q2 x n / 3600) + (Q
3 × n / 3600), which is a value corresponding to the area of the shaded portion in FIG. Therefore, an error occurs in the flow integrated value QS with respect to the actual flow. If the flow rate increase and decrease states (rise and fall) are almost the same, there will be no error in the total integrated value, but the actual use environment and use state will not necessarily result in the same increase and decrease states. Not limited to this, there is a high possibility that errors are integrated. For this reason, in the conventional flowmeter, a flow integrated value different from the actual flow value may be output, and further improvement in the accuracy of the flow integrated value is desired.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to improve the accuracy of a flow integrated value in a guess-type flow meter and to perform more accurate flow integration. It is an object of the present invention to provide a flowmeter and a flow measurement method capable of performing the measurement.

[0008]

In order to achieve the above-mentioned object, a flow meter according to the present invention calculates an integrated flow rate by intermittently measuring a flow rate in a flow path. A flow rate measuring means for obtaining an instantaneous flow rate measurement value at predetermined measurement time intervals, and a flow rate change of a current flow rate measurement value with respect to a previous flow rate measurement value for the obtained flow rate measurement value. If the flow rate change exceeds a predetermined range, the flow rate integration processing based on the current flow rate measurement value is not performed, and the flow rate change When the flow rate is within the predetermined range after exceeding the range, the flow rate integration processing is performed using the average value of the flow rate measurement values from the time when the flow rate integration processing was stopped to the immediately preceding measurement time as the flow rate measurement value during the flow rate change period. With said The flow integration processing based on the flow measurement values of the first time is performed, and when the state where the flow rate change is within the predetermined range continues, the flow integration processing based on the current flow measurement value is performed to obtain the flow integration value. Means.

Further, the flow meter according to claim 2 is the same as the claim 1.
In the flowmeter described in the above, the flow integration means, as an average value of the flow measurement value from the time when the integration process was stopped to the immediately preceding measurement time, the flow measurement value at the measurement time when the integration process was stopped, It is characterized in that the flow rate integration processing is performed using the arithmetic mean value with the flow rate measurement value in the immediately preceding measurement time.

[0010] The flow rate measuring method of the present invention is characterized by claim 3.
As described in the above, a flow measurement method in an inferential flow meter that intermittently measures a flow rate in a flow path to calculate an integrated flow rate, and obtains an instantaneous flow rate measurement value at predetermined measurement time intervals. A flow rate measurement step, a flow rate change determination step of determining a flow rate change of a current flow rate measurement value with respect to a previous flow rate measurement value with respect to the obtained flow rate measurement value, and a flow rate change rate based on the determination result in the flow rate change determination step. If the flow rate exceeds a predetermined range, the flow rate integration processing based on the current flow rate measurement value is not performed.If the flow rate change falls within the predetermined range after exceeding the predetermined range, the flow rate integration processing is stopped. The flow rate integration process is performed using the average value of the flow rate measurement values up to the immediately preceding measurement time as the flow rate measurement value during the flow rate change period, and the flow rate integration process based on the current flow rate measurement value is performed. If is the state is within a predetermined range is continued performs flow accumulation process based on the current flow rate measurement value, and having a flow rate integrating step for obtaining a flow rate integrated value.

According to a fourth aspect of the present invention, in the flow rate measuring method according to the third aspect, in the flow rate integrating step, the flow rate measurement value from the time when the integration process was stopped to the immediately preceding measurement time is measured. The flow rate integration processing is performed using an arithmetic average of the flow rate measurement value at the measurement time when the integration processing is stopped and the flow rate measurement value at the immediately preceding measurement time as an average value.

In the flow meter and the flow rate measuring method according to the present invention, when the flow rate change exceeds a predetermined range, the flow rate integrating process based on the current flow rate measurement value is stopped, and after the flow rate change exceeds the predetermined range. When the flow rate is within the predetermined range, the flow rate integration processing is performed using the average value of the flow rate measurement values from the time when the flow rate integration processing was stopped to the immediately preceding measurement time as the flow rate measurement value during the flow rate change period, and the current flow rate The flow rate integration processing based on the measured value is performed, and when the state where the flow rate change is within the predetermined range continues, by performing the flow rate integration processing based on the current flow rate measurement value, the flow rate increases or decreases during the flow rate measurement. Even in this case, a flow integrated value with a small error is obtained, and the accuracy of the flow integrated value is improved.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a flow meter and a flow measuring method according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is a configuration diagram showing a functional configuration of a main part of a flow meter according to an embodiment of the present invention.

The flow meter 10 has a flow rate measuring section 11 as a flow rate measuring means for measuring an instantaneous flow rate of a fluid such as a gas at predetermined measurement time intervals (sampling intervals), and performs a process of integrating the measured flow rate values. And a processing unit 12. In the example of FIG. 1, a flow sensor type flow rate measuring means is shown. The flow rate measuring unit 11 includes a heater 21 for heating.
Temperature sensors 22 and 23 disposed upstream and downstream of the heater 21;
And a measurement control unit 24 connected to the control units 2 and 23 for performing various controls of the flow rate measurement process.

The flow rate measuring means is not limited to the flow sensor type, and an ultrasonic type, a fluidic type or the like can be applied to the present invention.

The processing unit 12 receives the instantaneous flow measurement value output from the flow measurement unit 11 and performs various controls of the flow integration process, and stores the flow measurement value measured by the flow measurement unit 11. Based on the determination results of the flow rate measurement value storage unit 14, the flow rate change determination unit 15 as flow rate change determination means for determining whether the flow rate measurement value has changed beyond a predetermined range, and the flow rate change determination unit 14. A flow rate integrating section 16 as flow rate integrating means for integrating the flow rate, and a display section 17 for displaying the integrated value of the flow rate at the output end of the processing section 12
Is connected.

The processing unit 12 is realized by a microcomputer or the like, and more specifically, a CPU for performing various processes according to a software program,
The ROM has a built-in ROM that stores processing programs and the like performed by the U, a RAM that has a work area used in various processing steps in the CPU and a data storage area that stores various data, and the like, and these are connected by a bus. . Further, the measurement control unit 24 of the flow rate measurement unit 11 may be included in the processing unit 12.

Next, the operation of the flow meter according to the present embodiment will be described. In the flow rate measuring unit 11, under the control of the measurement control unit 24, the heater 21 heats gas and the like flowing on the surrounding flow path, and the temperature sensors 22 and 23 heat the heater 21.
The temperature of the upstream side and the downstream side is detected, and the instantaneous flow rate is calculated based on the temperature difference obtained from the outputs of these temperature sensors 22 and 23. The detected flow measurement value is sent to the processing unit 1
2 and the flow rate integrating process is executed.

FIG. 2 shows the details of the flow rate measurement and integration processing operation.
It will be described based on. In the integration processing operation in the processing section 12, the control section 13 controls the overall timing and the like. The input flow measurement value is stored in the flow measurement value storage unit 14 and held for a predetermined period.

First, as an initialization process, an initial flow rate Q0 =
0, a flow rate change flag DQ = 0 indicating a change state of the flow rate is set (step S1). Next, each time a predetermined measurement time (sampling time) is reached by the flow measurement unit 11, flow measurement is performed to obtain a flow measurement value (step S2: flow measurement step). And the previous flow measurement value is Qi
(Step S3) The current flow measurement value is set to Qj (Step S4).

In the present embodiment, when the flow rate measurement value integration process is performed, the flow rate change determination unit 15 determines whether the current flow rate measurement value Qj has changed from the previous flow rate measurement value Qi. . If the difference between the previous flow rate measurement value Qi and the current flow rate measurement value Qj is greater than a predetermined range setting value K, that is, if the flow rate change exceeds the range setting value K, the current flow rate measurement value Qj When the flow rate change falls within the range set value K without performing the integration, the flow rate integration unit 16 integrates the average flow value during the flow rate change. For example, when a flow measurement value as shown in FIG.
Since the flow rate difference is larger than the range setting value K from to Q4, the flow rate measurement value is not integrated. When the flow rate measurement value of Q5 is obtained and the flow rate difference falls within the range setting value K, the following formula is used. The flow amount up to this point is calculated and the flow measurement values are integrated.

The integrated flow value QS = (Q1 + Q4) / 2 × (n × 4) / 3600 + Q5 × n / 3600 (1) Here, the range setting value K is, for example, the current flow measurement value Qj
± m% (m = 1 to 5 or the like).

The above flow rate integrating process will be described in detail with reference to FIG. The absolute value | Qi of the difference between the previous measured flow rate Qi and the present measured flow rate Qj in the flow rate change determining unit 15
It is determined whether or not −Qj | is equal to or smaller than the range set value K (step S5: flow rate change determination step), and the following steps S6 to S6 are performed.
At S14, a flow rate integration step is executed.

If | Qi−Qj | is larger than the range set value K in step S5, the flow advances to step S6 to determine whether or not the flow rate change flag DQ is 0. When the flow rate change flag DQ is 0, the flow rate change flag DQ is set to 1 (step S7), and the accumulated time cnt is set to cnt = cnt + ts (step S8). Here, ts is one unit of the sampling interval (n seconds in the example of FIG. 3). If the flow rate change flag DQ is 1 in step S6, the process in step S8 is performed as it is. After that, the process waits for the sampling interval until the next measurement time (step S9), and returns to step S2
And the same processing is repeated.

On the other hand, in step S5, the previous measured flow rate Q
i | and the absolute value of the difference between the current flow measurement value Qj | Qi-Qj
Is less than or equal to the range set value K, the process proceeds to step S10, and it is determined whether or not the flow rate change flag DQ is 0. If the flow rate change flag DQ is 1, the flow rate integrating section 16
In step S11, the flow amount QT during the period from the start of the flow rate change to the current stabilization from the stable flow rate value up to the previous time is calculated by the following equation (step S11). Passage QT = ((Q0 + Qi) / 2) .times.cnt + Qj.times.ts (2)

Then, the initial flow rate Q0 and the flow rate change flag D
Q is set to Q0 = Qj and DQ = 0 (step S1).
2) The flow rate integrating section 16 integrates the passing amount QT by the following equation (step S13). Flow integrated value QS = QS + QT (3)

After the integration of the passing amount QT is completed, the process waits for the sampling interval until the next measurement time (step S9), returns to step S2, and repeats the same processing.

In step S10, the flow rate change flag DQ is set to 0.
In the case of (1), it is determined that there is no change in the flow rate of the current flow rate measurement value Qj with respect to the previous flow rate measurement value Qi, so the flow rate integration section 16 calculates the passing amount QT by the following equation (step S14). Passage QT = Qj × ts (4)

After the flow amount integrating section 16 integrates the passing amount QT in the same manner as described above to update the integrated flow amount QS (step S13), it waits for a sampling interval until the next measurement time (step S9). , Step S2
And the same processing is repeated.

An example of the result of the integration process of the flow measurement values is shown below, and a comparison with the case of the conventional method will be made. FIG. 4 is an explanatory view showing an example of the integration result by the conventional flow rate measuring method, and FIG. 5 is an explanatory view showing an example of the integration result by the flow rate measuring method of the present embodiment. This example shows a case where the actual flow measurement value fluctuates repeatedly due to the occurrence of a pulsating flow or the like.

In the conventional flow rate measuring method, the flow rate measured values Q1 to Q9, which are the instantaneous flow rates at that time, are added to the sampling interval n.
Since the value obtained by multiplying the second is sequentially accumulated, the integrated value of the flow rate (corresponding to the area indicated by oblique lines in FIG. 4)
QS is as follows: QS = Q1 × n / 3600 + Q2 × n / 3600 +... + Q8 × n / 3600 + Q9 × n / 3600 (5)

On the other hand, in the flow rate measuring method according to the present embodiment, the flow rate integrated value QS (corresponding to the area shown by oblique lines in FIG. 5) is QS = Q1 × n / 3600 + (Q1 + Q8) by the above flow rate integration processing. / 2 × (n × 7) / 3600 + Q9 × n / 3600 (6), and it is possible to obtain a flow integrated value with a smaller error with respect to the actual flow fluctuation.

The integrated flow value QS, which is the result of performing the integration process as described above, is output from the flow integration unit 16 and displayed on the display unit 17. Alternatively, the flow rate integrated value QS can be sent to an external device as numerical data.

When the average value during the change of the flow rate is integrated in the flow integration processing (step S11), the arithmetic mean of the flow measurement value Q0 which was stable up to the previous time and the flow measurement value Qi immediately before is integrated. Although the amount of passage is obtained by multiplying the value by the time of the period using the value, various modified examples such as using an average value of three or more flow rate measurement values in some cases are conceivable.

As described above, in the present embodiment, the integration process is not performed when the flow rate measurement value is increasing or decreasing beyond the predetermined range setting value, and when the flow rate change converges within the range setting value. The flow rate based on the average value of the flow rate measurement value at the start of the flow rate change (when the integration process is stopped) and the flow rate measurement value at the immediately preceding measurement time is calculated, integrated for the period, and added to the current flow rate measurement value. The passing amount based on the total is integrated. By performing the flow integration when the flow measurement value is stable without a change in the flow in this manner, the flow can be increased or decreased,
Even when a flow rate change such as a flow rate change due to a pulsating flow or the like occurs, an accurate flow rate integrated value with few errors can be obtained, and errors in the flow meter can be reduced and accuracy can be improved.

[0036]

As described above, according to the flow meter and the flow rate measuring method of the present invention, when the flow rate change of the current flow rate measurement value with respect to the previous flow rate measurement value exceeds a predetermined range, the flow rate integration is performed. If the flow rate change falls within the predetermined range after exceeding the predetermined range without performing the process, the average value of the flow rate measurement values from when the flow rate integration process was stopped until the immediately preceding measurement time is calculated as the flow rate change period. In addition to performing the flow integration process as the flow measurement value and performing the flow integration process based on the current flow measurement value, if the state where the flow rate change is within the predetermined range continues, the flow integration process based on the current flow measurement value is performed. Therefore, the accuracy of the flow integrated value can be improved in the guess-type flow meter, and more accurate flow integration can be performed.

[Brief description of the drawings]

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

FIG. 2 is a flowchart illustrating a procedure of a flow rate measurement and integration processing operation in the flow meter according to the embodiment.

FIG. 3 is an explanatory diagram illustrating an example of a flow rate measurement value in a flow rate integration process.

FIG. 4 is an explanatory diagram showing an example of an integration result by a conventional flow rate measuring method.

FIG. 5 is an explanatory diagram showing an example of an integration result by the flow rate measuring method of the embodiment.

FIG. 6 is an explanatory diagram showing a difference between an actual flow rate and a flow rate integrated value when a flow rate is in an increasing state in a conventional flow rate measuring method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Flow meter 11 Flow rate measurement part 12 Processing part 13 Control part 14 Flow rate measurement value storage part 15 Flow rate change judgment part 16 Flow rate integration part 17 Display part 21 Heater 22, 23 Temperature sensor 24 Measurement control part

Claims (4)

[Claims] 1. An inferential flow meter for intermittently measuring a flow rate in a flow path to calculate an integrated flow rate, comprising: a flow rate measuring means for obtaining an instantaneous flow rate measurement value at predetermined measurement time intervals; For the measured flow rate value, a flow rate change determining means for determining a flow rate change of the current flow rate measured value with respect to a previous flow rate measured value, and the flow rate change exceeds a predetermined range based on the determination result by the flow rate change determining means. In this case, the flow rate integration process based on the current flow rate measurement value is not performed, and if the flow rate change falls within the predetermined range after exceeding the predetermined range, the flow rate from when the flow rate integration process was stopped to the immediately preceding measurement time is measured. The flow rate integration process is performed based on the average value of the measured values as the flow rate measurement value in the flow rate change period, and the flow rate integration process based on the current flow rate measurement value is performed, and the state in which the flow rate change is within the predetermined range continues. And a flow rate integrating means for performing a flow rate integrating process based on the current flow rate measurement value to obtain a flow rate integrated value. 2. The flow rate integrating means calculates an average value of flow rate measurement values from the time when the integration processing is stopped to the immediately preceding measurement time as a flow rate measurement value at the measurement time when the integration processing is stopped and the immediately preceding flow rate measurement value. The flow meter according to claim 1, wherein the flow rate integration processing is performed using an arithmetic mean value with the flow rate measurement value at the measurement time. 3. A flow rate measuring method in an inferential flow meter for intermittently measuring a flow rate in a flow path to calculate an integrated flow rate, wherein an instantaneous flow rate measurement value is obtained at predetermined measurement time intervals. A measurement step, for the obtained flow rate measurement value, a flow rate change determination step of determining a flow rate change of a current flow rate measurement value with respect to a previous flow rate measurement value, based on the determination result in the flow rate change determination step,
When the flow rate change exceeds the predetermined range, the flow rate integration processing based on the current flow rate measurement value is not performed, and when the flow rate change falls within the predetermined range after exceeding the predetermined range, the flow rate integration processing is stopped. The flow rate integration process is performed based on the average value of the flow rate measurement values from time to the immediately preceding measurement time as the flow rate measurement value in the flow rate change period, and the flow rate integration process based on the current flow rate measurement value is performed. A flow rate integration step of performing a flow rate integration process based on the current flow rate measurement value to obtain a flow rate integration value if the state of being within is maintained. 4. In the flow rate integration step, an average value of the flow rate measurement values from the time when the integration processing is stopped to the immediately preceding measurement time is calculated as the average value of the flow rate measurement value during the measurement time when the integration processing is stopped. The flow rate measuring method according to claim 3, wherein the flow rate integrating process is performed using an arithmetic mean value with the flow rate measured value during the measuring time.