JP3621924B2 - Flowmeter - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a flow meter, is used for example gas or tap water.
[0002]
[Prior art]
For example, a flow meter that measures the actual amount of gas used is maintenance-free and has a service life of about 10 years. However, with a flow meter that is an electric device with a power source for driving and automatic management, The power supply voltage is suppressed to a very small value of about 3 V, and consideration is given to gas flammability. For this reason, power saving is a big problem, and as one measure, the flow rate is measured only in a predetermined period and the actual usage is integrated. Specifically, the measurement values of each time are sampled, and this measurement value is repeatedly integrated over time until the next sampling time point. The actual usage amount thus obtained, that is, the total integrated amount is displayed with an increase every time there is a change for a predetermined display unit, and is used for checking the usage status by the user and managing the gas supplier.
[0003]
[Problems to be solved by the invention]
However, in such a measurement method, even in the usage state at the same flow rate, the measured value measured at the next sampling time is compared to the integrated value displayed based on the measured value at the previous sampling time. The integrated amount at the time when the integrated display is performed may have a difference of multiple display units, and the actual usage increases at a constant rate in proportion to the time when the same flow rate is used. In this state, the display state of the integrated amount becomes a sudden change that jumps one or more steps of the display unit, and the display becomes unnatural. Such a situation is more likely to occur as the sampling period is made longer to save power, and the discontinuity of display becomes larger. In particular, in the numerical display, intermediate numbers are skipped by that amount, and the user is likely to feel discomfort and distrust.
[0004]
An object of the present invention is to provide a smooth Ru flowmeter which can be displayed by a change corresponding to the actual use state.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the flowmeter of the present invention includes a measuring unit that repeats measurement and sampling of the flow rate of a target fluid at a predetermined cycle, and a measurement value previously sampled by the measuring unit. The integration means for integrating the flow rate between the time until the sampling time and the integration amount integrated by the integration means into the unit flow rate per unit time obtained by dividing the time from the previous sampling time to the next sampling time. Conversion means for conversion, total integration means for obtaining a total integration amount by repeating integration of unit flow rates corresponding to the unit time each time a unit time set at each sampling time elapses, and this total integration means Display means for increasing the display amount of the flow rate each time the integrated amount accumulated by the display unit changes by the display unit, and Ring and, and said conversion means is for mainly characterized in that the have line conversion unit flow rate in unit time uniformly to cycle time divisible multiple sampling periods employed in a unit time setting .
[0006]
In such a configuration, the measured value is sampled at a cycle corresponding to the flow rate to suppress the integration error, and the smooth integration display according to the actual flow rate is performed by integrating the flow rate at the unit time and unit flow rate corresponding to the cycle. Can do.
[0007]
Further objects and features of the present invention will become apparent from the following detailed description and drawings. Each feature of the present invention can be used alone or in combination in various combinations as much as possible.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 3 for understanding of the present invention. The following description shows specific examples of the present invention and does not limit the description of the scope of claims.
[0009]
In the present embodiment, as shown in FIG. 1, gas is supplied to a user in each household and used for gas equipment such as a stove 1, hot water supply equipment 2, and heating equipment 3. It is an example in the case of the flowmeter 4 for detecting the usage-amount. However, the present invention is not limited to this, and is effective when applied to all cases of supplying and using tap water and other fluids, all of which belong to the category of the present invention.
[0010]
As shown in FIG. 1, the flow meter 4 of the present embodiment is provided with a measurement member 6 for indirectly detecting a flow rate in a flow path 5 for supplying a gas and a shutoff valve 7 for blocking the flow path 5. The flow rate detecting means 8 measures and samples the flow rate of the target fluid at a predetermined cycle by the measuring member 6 and repeats the integration of the flow rate up to the next sampling time with the sampled measurement value over time. The integrated value is displayed on the display unit 12 that is integral with or separate from the measurement unit 11. In addition to or separately from this, the data is transmitted to the administrator side through a line with the administrator side or a wireless transmission / reception unit 13 for management. Although this management is not shown, pressure information of the target fluid is also included, and flow rate detection and pressure detection according to a request from the manager side are also performed.
[0011]
The measurement member 6 includes, for example, a pair of ultrasonic transducers 6a and 6b that transmit and receive ultrasonic waves with a target fluid interposed therebetween, a flow rate detecting means 8, a driving transmission unit 10a, an amplification receiving unit 10b, and transmission / reception. It is connected to the flow rate detecting means 8 via the switching means 10c for switching the direction, and the upstream side from the ultrasonic transducer 6a on the downstream side with respect to the gas flow that is the target fluid flowing in the direction indicated by the arrow 114 by the flow rate detecting means 8. The arrival time when the ultrasonic wave is transmitted toward the ultrasonic transducer 6b and the arrival time when the ultrasonic wave is transmitted from the upstream ultrasonic transducer 6b toward the downstream ultrasonic transducer 6a Is measured, and the measured value is converted into a measured value of the flow rate of the gas flow to detect the flow rate. Actually, by summing the arrival times of each time when the ultrasonic waves are transmitted a plurality of times, it corresponds to the fact that the arrival time of one time is very small and difficult to handle. In addition, since the target fluid is gas and flammable, the power source of the flow meter 4 needs to be kept as low as about 3 V, for example, to ensure safety and to save power as much as possible to withstand maintenance-free use for about 10 years. Therefore, under the conditions where the flow rate is low and the time difference between upstream transmission and downstream transmission is difficult to obtain and accurate measurement is difficult, it is possible to respond by increasing the number of ultrasonic transmissions / receptions at the time of measurement. Reduce the number of times. In addition, the flow rate is measured at a predetermined cycle, the measured value is sampled, and the flow rate is integrated according to the elapsed time from this measured value to the next sampling time point to obtain the used flow rate. . Moreover, the sampling period is shortened when the flow rate is large and an error is likely to occur in the integration, but it is lengthened when the flow rate is small.
[0012]
FIG. 2 shows an example of the relationship between the flow rate Q and the number of ultrasonic transmissions / receptions. The number of transmissions / receptions N1 set corresponding to the flow rate Q1 and the number of transmissions / receptions N3 set corresponding to the flow rate Q3 are, for example, several times. Have an opening of. The flow rate detection means 8 alternately applies the drive signal S2 to the ultrasonic transducers 6a and 6b by the set number N in accordance with the measurement signal S1 shown in FIG. One driven by the drive signal S2 of the ultrasonic transducers 6a and 6b repeatedly transmits ultrasonic waves to the other for the set number of times N, and the other output for receiving the ultrasonic waves is monitored by the measuring means 14. The monitored output is waveform data S3 as in the example of the transmission / reception operation shown in FIG.
[0013]
In the figure, an example in which the number of times of transmission / reception is three is shown for simplicity of explanation. The data S3 in this transmission / reception operation example is schematically shown in an easy-to-understand manner with an expanded time width with respect to the transmission time width of the drive signal S2. However, there is a noise waveform before and after the data S3 portion, and the data S3 portion. Although the noise waveform that follows is attenuated, a so-called tailing state occurs, which remains for a relatively long time. Therefore, the next measurement is performed at the time after the noise waveform is attenuated for accurate measurement. Specifically, as shown in the transmission / reception operation example of FIG. 4, a waiting time tm until the tailing of the drive signal S2 is attenuated to a predetermined state is set for the measurement signal S1. In addition, when the transmission / reception operation is repeated a plurality of times, the partial reception waveform of the data S3 tends to gradually increase as shown in FIG. 4, and the reception start time is not clear due to the relationship with the noise waveform. Therefore, a time point ts that goes back the waveform for the number of times of reception from the zero-crossing time point te of the waveform at the final reception time when the reception waveform becomes large is determined as the reception start time point, and the time between them is handled as the total reception time.
[0014]
FIG. 3 shows an example of the relationship between the flow rate Q and the cycle T in which the flow rate is measured and sampled by an ultrasonic wave transmission / reception operation, and is set corresponding to the cycle T1 and the flow rate Q3 set corresponding to the flow rate Q1. For example, the period T3 has an opening of less than 10 times. Therefore, the measuring means 14 sets the measurement signal S1 to a cycle according to the flow rate Q as shown in FIG.
[0015]
FIG. 4 shows a case where the flow rate Q is simply changed to Q3, Q2, Q1, Q2 for the sake of simplicity of explanation. The sampling cycle T3 and the number of transmissions / receptions N3 with respect to the flow rate Q3, and the sampling cycle T2 with respect to the flow rate Q2. In addition, the sampling period T1 and the number of transmissions / receptions N1 are sequentially set for the flow rate Q1, and the sampling period T2 and the number of transmissions / receptions N2 are sequentially set for the flow rate Q2. Here, Q3>Q2> Q1, T3 <T2 <T1, and N3 <N2 <N1.
[0016]
Basically, the present invention does not specifically ask what measurement member 6 is used as the flow rate detection means 8 and what detection method is adopted, and the flow rate is determined based on the periodic flow rate measurement value. It can be applied to any flow meter that integrates the flow rate, and the target fluid and its intended use and supply purpose are not particularly questioned.
[0017]
The flow meter 4 of the present embodiment measures and samples the flow rate of the target fluid, that is, the flow rate at that time, for example, Q1, Q2, Q3, etc., at a predetermined period T, and sets the sampled measured values Q1, Q2, Q3 to The accumulated value is displayed while repeating the integration of the flow rate up to the next sampling point over time. In particular, the measured values Q1, Q2, and Q3 sampled each time and the time until the next sampling point are displayed. Is converted into unit flow rates ΔQ1, ΔQ2, and ΔQ3 per unit time Δt divided up to the next sampling time, and each time the unit time Δt elapses until the next sampling time, the unit flow ΔQ1 or Every time ΔQ2 and ΔQ3 are integrated into the current total integrated amount ΣQ, each time the total integrated amount ΣQ changes by the display unit, the display amount of the flow rate is simply displayed. For dividing up.
[0018]
In the example of the flow rate Q3 in FIG. 4, since the sampling period is T3 and the unit flow rate is ΔQ3, each time the unit time Δt elapses from the previous measurement time point to the next measurement time point, the step is ΔQ3. Accumulation is sequentially performed, and at the next sampling time, (T3 / Δt) × ΔQ3 can be accumulated smoothly, and this is continued while the flow rate Q3 continues. Similarly, during the flow rate Q2, the integration of (T2 / Δt) × ΔQ2 can be smoothly performed between the previous sampling time and the next sampling time in the sampling period T2 corresponding to the flow rate Q2, while the flow rate Q1. In the corresponding sampling cycle T1, integration of (T3 / Δt) × ΔQ3 can be smoothly performed between the previous sampling time and the next sampling time.
[0019]
In this way, by simply measuring the flow rate of the target fluid at a predetermined period T, the flow rate up to the next sampling time point is integrated over time with the measured values Q1, Q2, and Q3 at the previous sampling time point. The total flow is integrated and displayed, but this integrated amount is converted into unit flow rates ΔQ1, ΔQ2, and ΔQ3 per unit time divided up to the next sampling time point, so the unit depends on the number of divisions at that time The flow rates ΔQ1, ΔQ2, and ΔQ3 can be made equal to or less than an integer smaller than the display unit. Each time the unit time elapses, the unit flow rates ΔQ1, ΔQ2, and ΔQ3 are added to the current total accumulated amount ΣQ. Every time there is a change in the display unit in the total integrated amount ΣQ while accumulating, the display unit of the flow rate is increased by the display unit so that the display unit can be displayed without skipping even one level. However, it is possible to shift to the next sampling time. The display is the same for both graphs and numerical values as long as the change in quantity can be shown. Taking a numerical value as an example, if the display unit is 1 cc, select a unit flow 1 cc that is equal to it, or a unit time Δt that is 0.5 cc, 0.01 cc, 0.05 cc, etc. If the unit flow rates ΔQ3, ΔQ2, and ΔQ1 are obtained, the integrated flow rate ΣQ is integrated and displayed so as to continuously change as shown in FIG. 4 during the integrated display at the same flow rate Q. can do.
[0020]
Here, when the unit time and Δt are selected so that the sampling period T is 1 / integer, the final time point at which the integration for each unit time Δt at the same flow rate based on the measurement value at the previous sampling time point ends is As shown in FIG. 4, it coincides with the next sampling start time. Therefore, as long as there is no change in the flow rate Q, a display state in which the integrated display based on the measurement value obtained by periodic sampling smoothly changes in units of display over time can be obtained. Such a situation can be avoided, and a smooth display without a sudden change as shown in FIG. 4 can be achieved, and even in the numerical display, the numerical value does not skip.
[0021]
In order to achieve such a method, the flow rate detection means 8 of the present embodiment measures the flow rate of the target fluid and repeats sampling at a predetermined cycle, and the measurement means 14 performs sampling first. Integration means 15 that integrates the measured values Q3, Q2, Q1, etc. and the time until the next sampling time point, that is, the period T3, T2, T1, etc., and the integration amount 15 integrated by this integration means 15 Is converted into a unit flow rate ΔQ per unit time Δt obtained by dividing the time from the previous sampling time to the next sampling time, and each time the unit time Δt set at each sampling time elapses, A total integration unit 17 that obtains a total integration amount ΣQ by repeatedly integrating the unit flow rate ΔQ corresponding to the unit time Δt. There each time the total integrated amount ΣQ that integrated changes display unit of displays units one minute up to a flow rate display on the display unit 12. Note that the sampling period T, the number N of ultrasonic transmission / reception, the unit time Δt, the unit flow rate ΔQ, and the like that are set and handled in advance are input from the input unit 18. These can also be changed later. Thereby, the integrated display method as described above can be automatically achieved stably for a long period of time with high accuracy.
[0022]
Further, the flow rate detecting means 8 operates in conjunction with the control means 21, and for the measured flow rates Q1, Q2, Q3, etc., the control means 21 determines the sampling periods T1, T2, T3, etc. according to them and the number of times of transmission / reception. N1, N2, N3, etc. are automatically set. As described above, the cycle T is shortened according to the increase in the flow rate Q, and the flow rate can be measured with high accuracy by increasing the number of times of transmission and reception. Yes.
[0023]
In this way, even when the sampling period T is not constant according to the flow rate Q, when the result of monitoring the measured value changes from the previously sampled measured value, it is the time point t3, t5, etc. in FIG. Thereafter, there is no problem because the unit flow rate is obtained with the changed measurement value and integration is performed up to the next sampling time. For example, taking the time point t3 as an example, this can be handled by switching from integration at (T3 / Δt) × ΔQ3 minutes to integration at (T2 / Δt) × ΔQ2.
[0024]
In particular, if a plurality of sampling periods T1, T2, T3, etc. to be adopted are set so as to be divisible by the unit time Δt, the unit obtained by adopting a uniform unit time Δt for various periods T The continuity feature of integration with the flow rate ΔQ is not impaired. However, since the unit flow rate ΔQ varies depending on the difference between the periods T1, T2, and T3, it is necessary to consider so that the relationship of the unit flow rate ΔQ with respect to the display unit is not impaired. The same applies when different unit times Δt are set for different periods T1, T2 and T3 on condition that the unit flow rate ΔQ is equal to the display unit or is a smaller integer. The features are not impaired.
[0025]
When the sampling period T in the measuring means 14 exceeds the minimum period for a predetermined time, the control means 21 is the period T2 or T1 with respect to the period T3 in the example of FIG. 4, but the sampling period T2 or T1 at that time As shown by a broken line in FIG. 4 at a shorter cycle, for example, cycle T3, the flow rate is measured to monitor whether it has changed from the previously sampled measured values Q3 and Q2, and the previously sampled measured value Q2 and When changing from Q1, a sampling period corresponding to the changed measurement value is set to obtain the unit flow rate ΔQ, and integration up to the next sampling time is performed.
[0026]
As a result, the measured value Q is sampled at a period T corresponding to the flow rate to suppress an integration error, and the smoothness corresponding to the actual flow rate is obtained by integrating the flow rates at the unit time Δt and the unit flow rate ΔQ corresponding to the cycle T. Accumulated display is possible. In the example shown in FIG. 4, at a time other than the sampling time in the periods T2 and T1 set according to the flow rate, the flow rate Q is measured and sampled and monitored at the minimum cycle T1, as shown by a broken line. Accordingly, in the example shown in FIG. 4, when the operation is performed only by normal sampling, the change from the flow rate Q1 to the flow rate Q2 at t6 can be measured only at the next sampling time t9 in the cycle T2 corresponding to the flow rate Q2. However, it can be detected early by the sampling monitor at the time t7, and the correct integration can be started early by setting the sampling period T2 corresponding to the changed flow rate Q2 and the number N2 of transmission / reception. become.
[0027]
【The invention's effect】
According to the present invention, only by measuring the flow rate of the target fluid at a predetermined cycle, the flow rate up to the next sampling time point is integrated with the measured value at the previous sampling time point, and the total flow rate is calculated. It is integrated and displayed, but this integrated amount is converted to a unit flow rate per unit time divided up to the next sampling time, so the unit flow rate is equal to or less than the display unit depending on the number of divisions Each time the unit time elapses, the unit flow rate is integrated into the current total integrated amount. Whenever the total integrated amount changes for the display unit, the display amount of the flow rate is changed. By increasing the display unit, it is possible to shift to the next sampling point while displaying the display unit without skipping even one stage.
[Brief description of the drawings]
FIG. 1 is a block diagram showing one example of a flow meter according to an embodiment of the present invention.
FIG. 2 is a graph schematically showing the relationship between the flow rate and the number of transmission / reception employed by the apparatus of FIG.
FIG. 3 is a graph schematically showing the relationship between the flow rate employed by the apparatus of FIG. 1 and the sampling period when the flow rate is measured.
FIG. 4 is a time chart showing flow rate measurement and integration operations performed by the apparatus of FIG. 1;
[Explanation of symbols]
4 Flow meter 5 Flow path 6 Measuring member 8 Flow rate detecting means 11 Measuring part 12 Display part 14 Measuring means 15 Accumulating means 16 Conversion means 17 Total integrating means 18 Input part 21 Control means

Claims (4)

Measuring means for measuring and sampling the flow rate of the target fluid in a predetermined cycle, and integrating means for integrating the flow rate between the measured value sampled earlier by this measuring means and the time until the next sampling time Conversion means for converting the integrated amount integrated by the integration means into a unit flow rate per unit time obtained by dividing the time from the previous sampling time point to the next sampling time point, and a unit time set at each sampling time point Whenever the elapses, the total integration unit that obtains the total integrated amount by repeating the integration of the unit flow rate corresponding to the unit time, and the flow rate every time the integrated amount integrated by this total integration unit changes by the display unit Display means for increasing the display amount, the measurement means samples at a cycle according to the flow rate, and the conversion means is for the cycle There line conversion unit flow rate in units of law time, flow meter for the divisible time setting a plurality of sampling periods employed in a unit time. Measuring means for measuring and sampling the flow rate of the target fluid in a predetermined cycle, and integrating means for integrating the flow rate between the measured value sampled earlier by this measuring means and the time until the next sampling time Conversion means for converting the integrated amount integrated by the integration means into a unit flow rate per unit time obtained by dividing the time from the previous sampling time point to the next sampling time point, and a unit time set at each sampling time point Whenever the elapses, the total integration unit that obtains the total integrated amount by repeating the integration of the unit flow rate corresponding to the unit time, and the flow rate every time the integrated amount integrated by this total integration unit changes by the display unit Display means for increasing the display amount, the measurement means samples at a cycle according to the flow rate, and the conversion means is for the cycle Performs conversion unit flow rate in units of law time, flow meter unit of time, chosen to be as one in which the unit flow rate divided by an integer equal unit flow rate or the display unit as the display unit. Measuring means for measuring and sampling the flow rate of the target fluid in a predetermined cycle, and integrating means for integrating the flow rate between the measured value sampled earlier by this measuring means and the time until the next sampling time Conversion means for converting the integrated amount integrated by the integration means into a unit flow rate per unit time obtained by dividing the time from the previous sampling time point to the next sampling time point, and a unit time set at each sampling time point Whenever the elapses, the total integration unit that obtains the total integrated amount by repeating the integration of the unit flow rate corresponding to the unit time, and the flow rate every time the integrated amount integrated by this total integration unit changes by the display unit Display means for increasing the display amount, the measurement means samples at a cycle according to the flow rate, and the conversion means is for the cycle Performs conversion unit flow rate in units of law time, as well as the time divisible multiple sampling periods employed in a unit time setting, time unit, is one of the integer fraction of units equal flow or the display unit as the display unit It selected to be a unit flow flowmeter. When the sampling cycle of the measuring means exceeds the minimum cycle for a predetermined time, the flow rate is measured at a cycle shorter than the sampling cycle at that time, monitoring whether it has changed from the previously sampled measurement value, and sampling first 4. When changing from the measured value, the sampling rate corresponding to the changed measured value is set to obtain the unit flow rate, and integration up to the next sampling time is performed. The flow meter described in 1.

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