JP2011174788A - Flow rate measuring device and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure accurately, from the outside, based on sound or vibration, a flow rate of fluid flowing through a fluid circulation passage having a mechanism generating sound or vibration at every time when a fixed quantity of fluid passes. <P>SOLUTION: This flow rate measuring device 2 includes: a microphone 21 for detecting sound generated by a gas meter 1; and a device body 22 for performing operation processing for determining a gas flow rate by using a sound wave signal extracted by the microphone 21. An operation processing device 25 of the device body 22 is equipped with: a correlation detection part 273 for calculating autocorrelation of waveform data originated in the sound wave signal, and determining periodicity inherent in the waveform data; and a flow rate calculation part 28 for calculating the flow rate of gas passing through the gas meter 1 by estimating a generation period of sound generated by the gas meter 1 from the periodicity. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention provides a flow rate of a fluid flowing through a fluid flow path having a mechanism for generating sound or vibration every time a certain amount of fluid passes, such as a gas meter, without inserting a meter or the like in the flow path. The present invention relates to a flow rate measuring apparatus and method capable of measuring from the outside.

  Gas consumers, such as general houses, business establishments such as shops and factories, and buildings, are equipped with gas meters for measuring their gas consumption. This gas meter is generally an integrated flow meter, and its main purpose is to measure gas consumption in units of one month. For this reason, the resolution of a meter is low and it is unsuitable for the gas flow rate measurement in a short time (for example, about 1 minute-1 hour) unit. In the first place, since this type of gas meter is based on visual measurement, it is not suitable for use in controlling the device based on the gas flow rate per unit time. In order to perform such gas flow measurement, it may be possible to incorporate a new gas flow meter into the gas piping. However, it is difficult for consumers to obtain an understanding, and people other than the gas supplier are required to install such piping. Is virtually impossible to do.

  Patent Document 1 discloses a technique for solving such a problem. That is, focusing on the fact that a dry flow meter such as a gas meter generates sound or vibration every time a certain amount of fluid passes, the flow measurement system of Patent Document 1 measures the sound or vibration. And the flow volume of the fluid which passes a dry-type flow meter is measured by counting the sound or vibration exceeding a predetermined threshold level. The threshold level is set in order to distinguish the sound or vibration generated by the dry flow meter from noise.

JP 2007-17325 A

  However, the sound or vibration actually generated by the dry flow meter varies depending on the flow rate of the fluid passing through the dry flow meter. According to the inventor's experiment, for example, in a gas meter that is currently widely used, a relatively loud sound is generated when the amount of gas used is large, and a relatively small sound is generated when the amount of gas used is small. Therefore, in the method of Patent Document 1, unless the threshold level is sequentially set according to the gas usage status, the sound generated from the gas meter cannot be distinguished from the noise, that is, the sound generation cycle is accurately grasped. Therefore, accurate gas flow rate measurement cannot be performed. Such fluidization at the threshold level is actually difficult, and there is a limit to the threshold method.

  The present invention has been made in view of the above problems, and based on the sound or vibration, the flow rate of the fluid flowing through the fluid flow path provided with a mechanism that generates sound or vibration every time a certain amount of fluid passes, An object of the present invention is to provide a flow rate measuring apparatus and method capable of more accurately measuring from the outside.

  A flow rate measuring device according to one aspect of the present invention is a flow rate measuring device attached to the outside of a fluid flow path including a mechanism that generates sound or vibration every time a certain amount of fluid passes, and the mechanism is generated. Detecting means for detecting a sound or vibration to be performed and outputting the sound or vibration as waveform data; a period detecting means for calculating an autocorrelation of the waveform data to obtain a periodicity inherent in the waveform data; and the periodicity And a flow rate calculating means for calculating the flow rate of the fluid in the fluid flow passage by estimating the generation period of the sound or vibration from the flow rate (Claim 1).

  Further, the flow rate measuring method according to another aspect of the present invention detects sound or vibration generated by the mechanism outside a fluid flow path including a mechanism that generates sound or vibration every time a certain amount of fluid passes. A step of generating waveform data from the detected sound or vibration, calculating an autocorrelation of the waveform data, obtaining a periodicity inherent in the waveform data, and calculating the sound or vibration from the periodicity. The flow rate of the fluid in the fluid flow path is estimated from the step of estimating the generation cycle of vibration, the unit flow rate of the fluid required to generate one sound or vibration in the mechanism, and the estimated generation cycle. And a step of obtaining. (Claim 6).

  According to these configurations, the generation period of the sound or vibration is not obtained depending on the generation level of the sound or vibration, but the periodicity of the waveform data based on the sound or vibration is detected by autocorrelation calculation. The generation period of the sound or vibration is obtained. Such periodicity can be grasped regardless of the flow rate of the fluid as long as it is a mechanism that generates sound or vibration every time a certain amount of fluid passes. Therefore, even if the intensity or frequency of the sound or vibration generated by the mechanism changes, the generation period of the sound or vibration can be accurately detected, and the flow rate of the fluid can be accurately calculated.

  In the above configuration, it is preferable that the fluid is a gas and the mechanism that generates the sound or vibration is a dry flow meter that detects an integrated flow rate of the gas. According to this configuration, for example, the flow rate of the fluid passing through a dry flow meter such as a gas meter can be measured from the outside without particularly performing piping work or the like.

  In the above configuration, the detection means outputs first waveform data generated at a first sampling period in which the sound or vibration can be detected, and the period detection means converts the first waveform data into a predetermined time unit. It is desirable to include a waveform compression unit that generates second waveform data whose sampling period is lower than that of the first sampling period by determining the average value for each section.

  In general, the sound or vibration generated by the mechanism is about 1 to 3 kHz, and in order to detect this, the detection means needs to sample the sound or vibration at a shorter cycle (for example, 8 kHz). . The first waveform data acquired at such a sampling period may have a problem that the amount of data is too large and a heavy load is imposed on the arithmetic processing, and it is difficult to obtain autocorrelation. Therefore, by generating the second waveform data obtained by compressing the first waveform data by the waveform compression unit, it is possible to simplify the subsequent autocorrelation calculation process.

  In this case, the period detection unit sequentially shifts the template waveform on the second waveform data in a reference time unit, a template setting unit for setting a template waveform having a predetermined time width on the second waveform data, It is desirable to provide a correlation detection unit that obtains a correlation with the template waveform and detects a correlation peak. According to this configuration, the autocorrelation calculation process can be performed efficiently.

  The template setting unit preferably updates the template waveform based on the latest second waveform data for each predetermined period. According to this configuration, it is possible to sequentially set an appropriate template corresponding to a change in flow rate.

  According to the present invention, a flow rate measurement capable of accurately measuring the flow rate of a fluid flowing through a fluid flow path having a mechanism for generating sound or vibration every time a certain amount of fluid passes based on the sound or vibration. Apparatus and methods can be provided. Therefore, for example, it is possible to perform control operations of other devices based on the fluid flow rate per unit time.

It is a schematic diagram which shows the installation condition with respect to the gas meter of the flow measuring device which concerns on embodiment of this invention. It is a block diagram which shows the structure of a flow measuring device. It is a graph which shows an example of the waveform data of a sound. It is a graph which shows the waveform data which compressed the waveform data of FIG. It is a graph which shows an example of a template waveform. It is a schematic diagram for demonstrating the process which calculates | requires an autocorrelation. It is a graph which shows the calculation result of an autocorrelation. It is a flowchart which shows operation | movement of a flow measuring device.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing an installation state of a flow meter 2 according to an embodiment of the present invention with respect to a gas meter 1. The gas meter 1 is installed in units of gas customers such as general houses, business establishments such as shops and factories, buildings, and the like, and measures an integrated value of gas usage in the gas customers.

  A gas meter 1 (a fluid flow passage having a mechanism that generates sound or vibration every time a certain amount of fluid passes) is a dry flow meter that detects an integrated flow rate of gas (fluid), and performs a gas flow measurement operation. A gas to which a main body 11 provided with a mechanism for performing the operation, a display unit 12 including a counter meter for displaying a measurement result of a gas flow rate as a numerical value, and a terminal of an inlet pipe 101 connected to a commercial gas supply pipe An inflow port 13 and a gas outflow port 14 to which a terminal of a consumer's indoor gas pipeline 102 is connected are provided.

  The main body 11 includes a measuring chamber for performing gas intake and exhaust operations for measuring the gas flow rate. The metering chamber is divided into four by a diaphragm that reciprocates by gas pressure, and the gas sucked from the gas inlet 13 is sequentially passed through the four metering sections by the operation of a slide valve that switches between exhaust and intake. It is discharged from the outlet 14. The reciprocating motion of the diaphragm caused by such gas suction / discharge is transmitted to the integrating mechanism via the crankshaft, and the integrated flow rate value is measured based on the reciprocating motion number of the diaphragm.

  As described above, the gas meter 1 measures the gas flow rate based on the mechanical operation of the components such as the diaphragm and the crankshaft, and thus generates a sound (or vibration) due to the operation cycle. This operation sound is a periodic sound that is generated each time a certain amount of gas passes. In the present embodiment, based on the operation sound generated by the gas meter 1, the flow rate of the gas flowing from the inlet pipe 101 into the indoor gas pipeline 102, that is, the flow rate for measuring the gas usage amount in the consumer separately from the gas meter 1. A measuring device 2 is attached to the gas meter 1.

  The flow rate measuring device 2 includes a microphone 21 (detection means) and a device main body 22. The microphone 21 detects sound (or vibration) generated by the gas meter 1 and is installed on or in close proximity to the outer surface of the main body 11 of the gas meter 1. The apparatus main body 22 is electrically connected to the microphone 21 and performs arithmetic processing for obtaining a gas flow rate using the sound wave signal extracted by the microphone 21.

  FIG. 2 is a block diagram showing a detailed configuration of the flow rate measuring device 2. The flow rate measuring device 2 includes an amplification circuit (AMP) 23, a sound wave detection circuit 24, an arithmetic processing unit (CPU) 25, and an interface circuit (I / F) 26.

  The amplifier circuit 23 receives an electrical sound wave signal detected by the microphone 21 and amplifies the sound wave signal. The sound wave detection circuit 24 detects the sound wave signal output from the amplification circuit 23 at a sampling period (first sampling period) of 8 kHz, for example, and generates original waveform data (first waveform data). The sampling frequency of 8 kHz is selected because the operation sound generated by the gas meter 1 is about 1 to 3 kHz. In order to detect sound in this band, it is necessary to sample at a shorter period than this. Because there is.

  The arithmetic processing unit 25 performs various arithmetic processes for calculating a gas flow rate, and includes a cycle detection unit 27 (cycle detection unit) and a flow rate calculation unit 28 (flow rate calculation unit). The period detection unit 27 calculates the autocorrelation of the sound wave waveform data and obtains the periodicity inherent in the sound wave waveform data, and includes a waveform compression unit 271, a template setting unit 272, and a correlation detection unit 273.

  The waveform compression unit 271 divides the original waveform data in predetermined time units and obtains an average value for each division, thereby obtaining compressed waveform data (second waveform data) whose sampling period is lower than the sampling period of 8 kHz. Generate. The original waveform data acquired at a sampling period of about 8 kHz has a problem that the amount of data is too large and a heavy load is imposed on the arithmetic processing, and it is difficult to obtain autocorrelation. Therefore, the waveform compressing unit 271 simplifies the subsequent autocorrelation calculation process by compressing the original waveform data and generating compressed waveform data of about several Hz to 100 Hz, for example.

  FIG. 3 is a graph showing an example of the original waveform data 41 output from the sound wave detection circuit 24. The original waveform data 41 in FIG. 3 has two large peak values, a first peak value 41P1 and a second peak value 41P2. These peak values correspond to sounds generated due to the operation cycle of the gas meter 1. Here, the interval between the first peak value 41P1 and the second peak value 41P2 is about 2 seconds. Therefore, in the situation in which the original waveform data 41 is detected, the main body 11 of the gas meter 1 performs measurement of one measurement unit in about 2 seconds, so that the measurement unit is known. Gas flow rate can be obtained.

  Thus, since the first and second peak values 41P1 and 41P2 can be observed from the original waveform data 41, it is possible to grasp the operation state of the gas meter 1 from the original waveform data 41 itself. However, the original waveform data 41 includes some sub-peaks 41S in addition to the first and second peak values 41P1 and 41P2. In order to distinguish between the sub-peak 41S and the first and second peak values 41P1 and 41P2, it is necessary to set a predetermined threshold value and extract only the true peak value. In the example of FIG. 3, for example, if the threshold value is set to amplitude value = 20000, the two peak values can be distinguished.

  However, the sound actually generated by the gas meter 1 varies depending on the flow rate of the fluid passing through the gas meter 1. In gas meters that are currently widely used, a relatively loud sound is generated when the amount of gas used is large, and a relatively small sound is generated when the amount of gas used is small. Therefore, for example, when the threshold value is fixedly set to amplitude value = 20000, the sub-peak 41S may not be distinguished from the first and second peak values 41P1 and 41P2. That is, accurate gas flow measurement cannot be performed.

  Therefore, in the present embodiment, paying attention to the fact that the gas usage state generally does not change abruptly at the consumer, the autocorrelation of the original waveform data 41 is examined, and the periodicity is obtained. Find the unit of measure (ie, the frequency of sound generation). However, the original waveform data 41 shown in FIG. 3 has data of 8000 samples per second, and there is too much data to extract a cycle of several seconds. That is, even if autocorrelation processing is performed based on the original waveform data 41, periodicity cannot be observed. In view of this point, the waveform compression unit 271 compresses the original waveform data 41.

  As an example, the waveform compression unit 271 partitions the original waveform data 41 in units of time of 1000 samples (0.125 seconds), and obtains an average value of the amplitude values of the 1000 samples, so that one amplitude data for each partition Create As a result, as shown in FIG. 4, compressed waveform data 42 having a sampling period of 8 Hz is generated. In the compressed waveform data 42, a first peak value 42P1 and a second peak value 42P2 corresponding to the first peak value 41P1 and the second peak value 41P2 of the original waveform data 41 appear.

  The template setting unit 272 sets a template waveform having a predetermined time width on the compressed waveform data 42. The template waveform is a reference waveform for obtaining the periodicity of the compressed waveform data 42, and the template setting unit 272 sets a reference time on the compressed waveform data 42, and before, after, or before and after the reference time. The data existing in a certain time width is set in the template waveform. The time width of the template waveform is about several seconds, and the time width may be fixed or variable. FIG. 5 is a graph showing an example of the template waveform 43 set by the template setting unit 272.

  The correlation detection unit 273 sequentially shifts the template waveform 43 as shown in FIG. 5 on the compressed waveform data 42 in units of reference time to obtain an autocorrelation with the template waveform 43 and detect a correlation peak. Specifically, the correlation detection unit 273 slides the template waveform 43 on the compressed waveform data 42 from the reference time on the basis of the reference time (0.125 seconds), and correlates the template waveform 43 with the compressed waveform data 42. Ask for.

  FIG. 6 is a diagram schematically showing this slide process. The template waveform 43 has a plurality of data at times before and after the data of the reference time Zt. Such a template waveform 43 is slid in units of reference time, and autocorrelation values C1, C2, C3... Are obtained for each slide. When the compressed waveform data 42 has a certain periodicity, when the template waveform 43 is slid, a correlation peak between the template waveform 43 and the compressed waveform data 42 appears at the certain period. Then, by determining the interval at which the correlation peak appears, the periodicity of the compressed waveform data 42, that is, the operating sound generation cycle of the gas meter 1 is determined.

The autocorrelation function _{r k} is a sequence of _{C 0} of the template waveform, the sequence of examining the symmetry When _{C k,} can be expressed by r _{k =} C k / _{C 0.} However, C _k is expressed by the following equation.

FIG. 7 is a graph illustrating an example of the calculation result of the autocorrelation data 44 by the correlation detection unit 273. In the autocorrelation data 44, four peaks of first to fourth correlation peaks 44P1 to 44P4 appear. The first correlation peak 44P1 appearing at the reference time (= 0s) is “1” because C _k = C ₀ . Hereinafter, second, third, and fourth correlation peaks 44P2, 44P3, and 44P4 appear at times t1, t2, and t3, respectively. These three peaks occur at a slide position on the compressed waveform data 42 that has a high similarity to the template waveform 43. The intervals between the first to fourth correlation peaks 44P1 to 44P4, that is, the times t1, t2, and t3 are about 2 seconds, and the periodicity can be confirmed.

  As described above, after detecting the autocorrelation of the compressed waveform data 42 using the template waveform 43, the correlation detection unit 273 extracts a correlation peak and obtains the generation interval of these correlation peaks. This generation interval is the generation interval of the operation sound of the gas meter 1. According to such a method, even if the operation sound of the gas meter 1 varies depending on the gas flow rate, or even if the microphone 21 picks up noise, the operation sound can be accurately extracted without any particular problem.

  Here, although the usage condition of the gas does not change rapidly, it changes with the passage of time. That is, the operation sound generation interval of the gas meter 1 changes. As is apparent from FIG. 7, it can be seen that the fourth correlation peak 44P4 that is farthest in time from the reference time has a lower correlation peak value than the second and third correlation peaks 44P2 and 44P3. Therefore, the template waveform 43 is sequentially updated based on the compressed waveform data 42 every predetermined period. The template waveform 43 is updated, for example, at regular intervals (for example, every 5 to 10 seconds), at regular intervals (for example, every 3 to 5 cycles), or the correlation peak value is a predetermined threshold value. It is possible to adopt a method of updating when the value falls below.

  The flow rate calculation unit 28 estimates that the period of the correlation peak detected by the correlation detection unit 273 is the generation period of the operation sound of the gas meter 1, and calculates the flow rate of the gas flowing through the gas meter 1 (indoor gas pipeline 102). To do. Specifically, the flow rate calculation unit 28 calculates the number of operation sounds generated as a period of the correlation peak in one unit of measurement in the main body 11 of the gas meter 1, that is, the amount of gas per operation sound generated once. By multiplying, the gas flow rate is calculated.

  The interface circuit 26 is provided to connect the external device 30 and the flow rate measuring device 2 so that they can communicate with each other. The external device 30 is a device that uses gas as fuel, and is a device that uses gas consumption per unit time or the like as one of its control elements, such as a fuel cell device.

  Next, the operation of the flow rate measuring device 2 will be described based on the flowchart shown in FIG. The arithmetic processing unit 25 acquires the original waveform data 41 (see FIG. 3) of the sound wave signal detected by the microphone 21 from the sound wave detection circuit 24 at a predetermined timing for a predetermined period (step S1). Then, the waveform compression unit 271 performs an averaging process, compresses the original waveform data 41, and creates compressed waveform data 42 (see FIG. 4) (step S2).

  Thereafter, the template setting unit 272 confirms whether or not the template waveform is set to be valid (step S3). That is, it is confirmed whether or not the template waveform is set and whether or not the set template waveform has expired. If the template waveform is not valid (NO in step S3), the template setting unit 272 sets the reference time on the compressed waveform data 42, and the waveform data existing within a certain time width based on the reference time is used as the template waveform 43. (See FIG. 5) (step S4). On the other hand, if the template waveform is valid (YES in step S3), this step S4 is skipped and the already set template waveform is utilized.

  Subsequently, the correlation detection unit 273 performs processing for obtaining autocorrelation of the compressed waveform data 42 using the template waveform 43 (step S5). By this process, a correlation peak is obtained, and further, a time between correlation peaks is obtained to obtain a generation period of the correlation peak (step S6). This generation period corresponds to the generation interval of the operation sound of the gas meter 1.

  Thereafter, the flow rate calculation unit 28 converts the generation period of the correlation peak obtained in step S6 into the gas flow rate, and obtains the gas flow rate per unit time (step S7). The gas flow rate data is output to the external device 30 via the interface circuit 26 (step S8). Thereafter, whether or not to continue the process is confirmed (step S9). If the process is to be continued (YES in step S9), the process returns to step S1 and is repeated. On the other hand, if the process is not continued (NO in step S9), the process ends.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to this, For example, the following modified embodiment can be taken.

  (1) In the said embodiment, the gas meter 1 of city gas was illustrated as an example of the fluid flow path provided with the mechanism which generate | occur | produces a sound or a vibration. Instead of this, a metering device that measures other gases such as air or oxygen, or a liquid such as water or oil, and that generates sound or vibration every time a certain amount of fluid passes, The invention can be applied. In addition, a device other than the metering device may be used as long as it includes a device that generates sound or vibration every time a certain amount of fluid passes.

  (2) In the above embodiment, the microphone 21 is exemplified as the detection means, and the example in which the gas flow rate is obtained using the sound wave signal detected by the microphone 21 has been described. Instead of this, a vibration sensor may be used as detection means, and may be brought into close contact with the main body 11 of the gas meter 1 to detect vibration caused by an operation occurring in the main body 11.

  (3) In the above embodiment, the example in which the gas flow rate data obtained by the flow rate measuring device 2 is output to the external device 30 via the interface circuit 26 has been described. Instead of this, the function of the flow rate measuring device 2 may be built in the external device 30.

1 Gas meter (dry flow meter)
DESCRIPTION OF SYMBOLS 11 Main-body part 12 Display part 2 Flow volume measuring apparatus 21 Microphone (detection means)
DESCRIPTION OF SYMBOLS 22 Apparatus main body 23 Amplification circuit 24 Sound wave detection circuit 25 Arithmetic processor 26 Interface circuit 27 Period detection part (period detection means)
271 Waveform compression unit 272 Template setting unit 273 Correlation detection unit 28 Flow rate calculation unit (flow rate calculation means)
30 External equipment

Claims (6)

A flow rate measuring device attached to the outside of a fluid flow path having a mechanism for generating sound or vibration every time a certain amount of fluid passes,
Detecting means for detecting sound or vibration generated by the mechanism and outputting the sound or vibration as waveform data;
A period detection means for calculating the autocorrelation of the waveform data and obtaining periodicity inherent in the waveform data;
A flow rate calculating means for estimating the generation period of the sound or vibration from the periodicity and calculating the flow rate of the fluid in the fluid flow path;
A flow rate measuring device comprising: The fluid is a gas;
The flow rate measuring apparatus according to claim 1, wherein the sound or vibration generating mechanism is a dry flow meter that detects an integrated flow rate of the gas. The detection means outputs first waveform data generated at a first sampling period in which the sound or vibration can be detected,
The period detecting means divides the first waveform data in a predetermined time unit, and obtains an average value for each section, thereby generating second waveform data whose sampling period is lower than the first sampling period. The flow rate measuring device according to claim 1, further comprising a waveform compression unit. The period detecting means includes
A template setting unit for setting a template waveform having a predetermined time width on the second waveform data;
A correlation detector that sequentially shifts the template waveform on the second waveform data in a reference time unit to obtain a correlation with the template waveform and detect a correlation peak;
The flow rate measuring device according to claim 3, comprising:   The flow rate measuring device according to claim 4, wherein the template setting unit updates the template waveform based on the latest second waveform data for each predetermined period. Detecting the sound or vibration generated by the mechanism outside the fluid flow path comprising a mechanism for generating sound or vibration each time a certain amount of fluid passes;
Generating waveform data from the detected sound or vibration;
Calculating the autocorrelation of the waveform data and determining the periodicity inherent in the waveform data;
Estimating the generation period of the sound or vibration from the periodicity;
Obtaining the flow rate of the fluid in the fluid flow path from the unit flow rate of the fluid required for generating one sound or vibration in the mechanism and the estimated generation period. The flow measurement method.

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