JP2004354398A - Flowmeter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flowmeter which is designed so as to indicate measurements in smooth variation depending on the actual working conditions. <P>SOLUTION: The flowmeter measures the flow rate of an intended fluid, for instance, in a given cycle T1 to sample it, and uses this sampled measurement Q1 to repeatedly integrate flow rate, up to the next sampling time point per elapse of time. To indicate this integrated value, the flowmeter converts the integrated amount, obtained from both each time sampled measurement Q1 and time T1 up to the next sampling time point, into an unit flow rate ΔQ per unit time Δt, partitioned up to the next sampling time point, and then increments the read amount of flow rate by indication unit, each time variation by an indication unit in total integrated amount ΣQ occurs, while integrating just amount of the unit flow rate ΔQ to the present total integrated amount ΣQ, each time the unit time Δt passes through the next sampling time point. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a flow meter, and is used for gas and tap water, for example.

  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, in a flow meter that is an electric device that has a power supply for driving and automatic management, The power supply voltage is extremely small, about 3 V, in consideration of gas flammability. For this reason, power saving is a major problem, and one measure is to measure the flow rate only at a predetermined cycle and integrate the actual usage. More specifically, the process repeats sampling the measured value of each time and integrating the measured value with the lapse of time until the next sampling time. The actual usage amount obtained in this way, that is, the total integrated amount, is increased and displayed every time there is a change of a predetermined display unit, and is used by the user to confirm the usage status and to manage the gas supplier.

  However, in such a measurement method, even in the state of use at the same flow rate, the integrated value displayed based on the measured value at the previous sampling point is replaced by the measured value measured at the next sampling point. In some cases, the integrated amount at the time when the integrated display based on the display is performed has a difference of a plurality of display units, and the actual usage increases at a constant rate in proportion to the time when the same flow rate is used. However, the display state of the integrated amount changes suddenly by jumping one or more steps in the display unit, and the display becomes unnatural. Such a phenomenon is more likely to occur as the sampling cycle is lengthened to save power, and the discontinuity of display increases. In particular, in the numerical display, intermediate numbers are skipped by that much, and it is easy for the user to feel uncomfortable or distrustful.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a flow meter capable of displaying a smooth change according to an actual use state.

  In order to achieve the above object, a flow meter according to the present invention includes a measuring unit that repeats a measurement and a sampling of a flow rate of a target fluid at a predetermined cycle, and a measurement value previously sampled by the measurement unit and a next measurement value. Integrating means for integrating the flow rate from the time up to the sampling time, and the integrated amount integrated by the integrating means into a unit flow per unit time obtained by dividing the time from the previous sampling time to the next sampling time. Conversion means for converting, every time a unit time set at each sampling time elapses, total integration means for obtaining a total integration amount by repeating integration of a unit flow rate corresponding to the unit time, and this total integration means Display means for increasing the display amount of the flow rate each time the integrated amount of the total changes by the display unit. Ring and, and said conversion means is for mainly characterized in that the conversion unit flow rate in unit time of uniformly to the period.

  In such a configuration, the measured value is sampled at the cycle corresponding to the flow rate, and the integration error is suppressed, while the integration of the flow rate at the unit time and the unit flow rate corresponding to the cycle enables the smooth integration display according to the actual flow rate Can be.

  According to the present invention, it is possible to shift to the next sampling point while displaying the display unit without skipping even one stage.

  According to a first aspect of the present invention, there is provided a measuring means for repeating a predetermined cycle of measuring and sampling a flow rate of a target fluid, and a measuring value previously sampled by the measuring means and a time up to a next sampling time. Integrating means for integrating the flow rate, converting means for converting the integrated amount integrated by the integrating means into a unit flow per unit time obtained by dividing the time from the previous sampling time to the next sampling time, and each sampling time Each time the unit time set in step elapses, a total integrating means for obtaining the total integrated amount by repeatedly integrating the unit flow rate corresponding to the unit time, and a display unit for the total amount integrated by the total integrating means. Display means for increasing the display amount of the flow rate every time the flow rate changes by minutes, wherein the measurement means samples at a cycle corresponding to the flow rate, and the conversion means By converting the unit flow rate in a uniform unit time with respect to the cycle, the measurement value is sampled in the cycle corresponding to the flow rate and the integration error is suppressed, while the flow rate in the unit time and the unit flow rate corresponding to the cycle is The integration enables a smooth integration display corresponding to the actual flow rate.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited by the embodiment.

(Embodiment 1)
As shown in FIG. 1, the present embodiment supplies gas to a user such as a household and supplies gas to a gas appliance such as a stove 1, a hot water supply unit 2, and a heating unit 3. This is an example of the case of a flow meter 4 for detecting the usage amount. However, the present invention is not limited to this, and is effective when applied to all cases where tap water and other fluids are supplied and used, and all of them are included in the scope of the present invention.

  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 and a shutoff valve 7 for shutting off the flow path 5 in a flow path 5 for supplying gas. The flow rate detecting means 8 measures the flow rate of the target fluid at a predetermined cycle by the measuring member 6 and samples the flow rate, and repeatedly integrates the flow rate up to the next sampling time with the lapse of time based on the sampled measurement value. The integrated value is displayed on the display unit 12 integrated with or separate from the measurement unit 11. At the same time or separately, the information is transmitted to the administrator through a line with the administrator or a wireless transmission / reception unit 13 for management. Although this management is not shown, it includes pressure information of the target fluid and the like, and the flow rate detection and the pressure detection are also performed according to the request from the manager side.

  The measuring member 6 has, for example, a pair of ultrasonic transducers 6a and 6b for transmitting and receiving ultrasonic waves with a target fluid interposed therebetween, and includes a flow rate detecting means 8, a transmitting unit 10a for driving, a receiving unit 10b for receiving amplified signals, and a transmitting and receiving unit. It is connected to the flow rate detecting means 8 via the switching means 10c for switching the direction, and the flow rate detecting means 8 causes the gas flow as the target fluid flowing in the direction indicated by the arrow 114 from the ultrasonic transducer 6a on the downstream side to the upstream side. And the arrival time when the ultrasonic wave is transmitted toward the ultrasonic vibrator 6b, and the arrival time when the ultrasonic wave is transmitted from the upstream ultrasonic vibrator 6b to the downstream ultrasonic vibrator 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 up the arrival times of the ultrasonic waves each time when they are transmitted a plurality of times, it is possible to cope with the fact that one arrival time is extremely short and it is difficult to handle. In addition, since the target fluid is gaseous and flammable, the power supply of the flowmeter 4 must be kept small, for example, about 3 V, to ensure safety, and to save power as much as possible to withstand maintenance-free use for about 10 years. Therefore, under conditions where the flow rate is small and the time difference between the upstream transmission and the downstream transmission is difficult to obtain and accurate measurement is difficult, the number of times of transmission and reception of ultrasonic waves during the measurement is increased to respond. Reduce the number of times. At the same time, the measurement of the flow rate is performed 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 point, thereby obtaining the used flow rate and the like. . In addition, the sampling period is shortened when the flow rate is large and an error is likely to occur in the integration, but is increased when the flow rate is small.

  FIG. 2 shows an example of the relationship between the flow rate Q and the number of times of transmission / reception of ultrasonic waves. The number of times of transmission / reception N1 set corresponding to the flow rate Q1 and the number of transmission / reception times N3 set corresponding to the flow rate Q3 are, for example, several times. To have an opening. The flow rate detecting means 8 alternately applies the driving signal S2 to the ultrasonic vibrators 6a and 6b by the set number N by the switching means 10c according to the measurement signal S1 shown in FIG. One of the ultrasonic vibrators 6a and 6b driven by the drive signal S2 repeatedly transmits an ultrasonic wave toward the other a set number of times N, and the other output receiving the ultrasonic wave is monitored by the measuring means 14. This monitored output is waveform data S3 as in the transmission / reception operation example shown in FIG.

  The figure shows an example in which the number of transmissions and receptions is set to three for simplicity of explanation. The data S3 of this transmission / reception operation example is schematically shown in an easy-to-understand manner with a time width expanded with respect to the transmission time width of the drive signal S2, but there is a noise waveform before and after the data S3 portion, and the data S3 portion. The noise waveform that follows is attenuated but remains for a relatively long time, that is, a so-called tailing state occurs. Therefore, the next measurement is performed at a point after the noise waveform has 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 attenuates to a predetermined state is set with respect to the measurement signal S1. Further, in the repetition of the transmission / reception operation a plurality of times in a short time, 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 point in time ts, which is the number of receptions from the zero-cross point te of the waveform at the final reception point when the reception waveform becomes large, is determined to be the reception start point, and the time between them is treated as the total reception time.

  FIG. 3 shows an example of a relationship between the flow rate Q and a cycle T for measuring and sampling the flow rate by the transmission / reception operation of the ultrasonic wave. The cycle T1 is set corresponding to the flow rate Q1 and the cycle T1 is set corresponding to the flow rate Q3. The period T3 has, for example, a difference of less than 10 times. Accordingly, the measuring means 14 sets the measurement signal S1 to a cycle according to the flow rate Q as shown in FIG.

  FIG. 4 shows a case where the flow rate Q simply changes to Q3, Q2, Q1, and Q2 for simplicity of description, and the sampling cycle T3 and the number of transmissions / receptions N3 for the flow rate Q3 are different from the sampling cycle T2 for the flow rate Q2. In addition, the number of transmissions / receptions N2, the sampling period T1 and the number of transmissions / receptions N1 for the flow rate Q1, and the sampling period T2 and the number of transmissions / receptions N2 for the flow rate Q2 are sequentially set in accordance with the change in the flow rate. Here, Q3> Q2> Q1, T3 <T2 <T1, and N3 <N2 <N1.

  Basically, the present invention does not particularly ask what kind of measuring member 6 is used as the flow rate detecting means 8 and what kind of detecting method is used. The present invention can be applied to any flow meter of a type that integrates the flow rate, and there is no particular limitation on the target fluid and its purpose of use and supply.

  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, and the like at a predetermined cycle T, and obtains the sampled measurement values Q1, Q2, Q3. The accumulated value is displayed while repeating the integration of the flow rate up to the next sampling time with the passage of time. In particular, the measured values Q1, Q2, and Q3 sampled at each time and the time until the next sampling time are displayed. Is converted into the unit flow rates ΔQ1, ΔQ2, and ΔQ3 per unit time Δt obtained by dividing the integrated flow amount obtained from to the next sampling time point. Each time the unit time Δt elapses until the next sampling time point, the unit flow rate ΔQ1 While integrating ΔQ2 and ΔQ3 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 displayed. For dividing up.

  In the example of the flow rate Q3 in FIG. 4, since the time of the sampling cycle 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, it is stepped by ΔQ3. In the next sampling, the integration of (T3 / Δt) × ΔQ3 can be performed smoothly, and the integration is continued while the flow rate Q3 continues. Similarly, in the sampling period T2 corresponding to the flow rate Q2, integration of (T2 / Δt) × ΔQ2 can be smoothly performed between the previous sampling time and the next sampling time. In the sampling period T1 corresponding thereto, the integration of (T3 / Δt) × ΔQ3 can be smoothly performed between the previous sampling time and the next sampling time.

  By simply measuring the flow rate of the target fluid at the predetermined cycle T in this manner, the flow rate up to the next sampling time point is repeatedly integrated with the measurement values Q1, Q2, and Q3 at the previous sampling time point over time. The total flow rate is integrated and displayed. This integrated amount is converted into unit flow rates ΔQ1, ΔQ2, and ΔQ3 per unit time obtained by dividing the time until the next sampling time. The flow rates ΔQ1, ΔQ2, and ΔQ3 can be equal to or smaller than the display unit, and can be set to a fractional integer. Each time the total integrated amount ΣQ changes by the display unit, the display amount of the flow rate is increased by the display unit, so that the display unit can be displayed without skipping even one stage. Then, it is possible to shift to the next sampling time. The display is the same whether it is a graph or a numerical value as long as the amount change can be shown. Taking a numerical value as an example, if the display unit is 1 cc, a unit flow rate of 1 cc which is equal to it, or a unit time Δt which is a fraction of 0.5 cc, 0.01 cc, 0.05 cc, etc., is selected. If the unit flow rates ΔQ3, ΔQ2, and ΔQ1 are obtained by the above, during the integration display at the same flow rate Q, the integrated flow rate ΣQ is integrated so that the integrated flow rate ΣQ changes continuously as shown in FIG. can do.

  Here, if both the unit time and Δt are selected so that the sampling period T is a fraction of an integer, the final time at which the integration for each unit time Δt at the same flow rate based on the measurement value at the previous sampling time is completed 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 is obtained in which the integrated display based on the measurement value obtained by the periodic sampling smoothly changes by the display unit with the lapse of time, and the numerical value jumps even if the numerical display is stepwise. Such a situation can be avoided, a smooth display without a sudden change as shown in FIG. 4 can be achieved, and the numerical value does not jump even in the numerical display.

  In order to achieve such a method, the flow rate detecting means 8 of the present embodiment measures the flow rate of the target fluid and performs sampling at a predetermined cycle, and the measuring means 14 Integrating means 15 for integrating the flow rate Q between the measured values Q3, Q2, Q1 and the like and the time until the next sampling time, that is, the cycle T3, T2, T1, etc., and the integrated amount integrated by the integrating means 15 Converting means 16 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 integrating means 17 for obtaining a total integrated amount ΣQ by repeating integration of a unit flow rate ΔQ corresponding to a 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 transmission / reception of ultrasonic waves, the unit time Δt, the unit flow rate ΔQ, and the like, which are set and handled in advance, are input from the input unit 18. These can be changed later. Thus, the above-described integration display method can be automatically and stably achieved for a long time with high accuracy.

  Further, the flow rate detecting means 8 operates in conjunction with the control means 21 so that the control means 21 responds to the measured flow rates Q 1, Q 2, Q 3, etc., according to the sampling periods T 1, T 2, T 3, etc. N1, N2, N3, etc. are automatically set. As described above, the cycle T is shortened in accordance with the increase of the flow rate Q, and the number of times of transmission / reception is increased so that the flow rate can be measured with high accuracy. I have.

  Even when the sampling period T is not constant according to the flow rate Q in this way, when the result of monitoring the measured value changes from the previously sampled measured value, it is a time point such as t3 or t5 in FIG. Thereafter, there is no problem because the unit flow rate is obtained from the changed measured value and integration is performed until the next sampling time. For example, taking the time point t3 as an example, it can be handled by switching from the integration of (T3 / Δt) × ΔQ3 to the integration of (T2 / Δt) × ΔQ2.

  In particular, if a plurality of sampling periods T1, T2, T3, etc. to be adopted are set to a time that is divisible by the unit time Δt, even if a uniform unit time Δt is adopted for various periods T, a unit obtained by the unit time is obtained. The continuity feature of the 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 take care that the relationship between the unit flow rate ΔQ and the display unit is not impaired. The same applies to the case where different unit times Δt are set for different periods T1, T2, and T3 on the condition that the unit flow rate ΔQ is equal to the display unit or a fractional integer smaller than the display unit. Said features are not impaired.

  When the sampling period T in the measuring unit 14 exceeds the minimum period by a predetermined time, the control unit 21 uses the period T2 or T1 with respect to the period T3 in the example of FIG. As shown by a broken line in FIG. 4 at a shorter cycle, for example, a cycle T3, the flow rate is measured and monitored for a change from the previously sampled measured values Q3 and Q2. When it changes from Q1, a sampling cycle corresponding to the changed measured value is set thereafter to obtain the unit flow rate ΔQ, and integration is performed until the next sampling time.

  Thereby, while the measurement value Q is sampled at the cycle T corresponding to the flow rate to suppress the integration error, the flow rate is integrated at the unit time Δt and the unit flow rate ΔQ corresponding to the cycle T, and the smoothness corresponding to the actual flow rate is obtained. Multiplication display is possible. In the example shown in FIG. 4, the flow rate Q is measured and sampled and monitored at the minimum cycle T1 as shown by the broken line, except for the sampling time at the cycles T2 and T1 set according to the flow rate. Thus, 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 cannot be measured until the next sampling time t9 in the cycle T2 corresponding to the flow rate Q2. However, it can be detected early by the monitor by sampling at the time t7, and the sampling cycle T2 and the number of transmissions / receptions N2 corresponding to the changed flow rate Q2 can be set so that correct integration can be started early. become.

  As described above, the flow meter according to the present invention can perform display with a smooth change according to the actual use state, and can be applied to a flow meter for gas, tap water, and the like.

It is a block diagram showing one example of a flow meter concerning an embodiment of the invention. 2 is a graph schematically illustrating a relationship between a flow rate and the number of times of transmission / reception adopted by the apparatus of FIG. 1. 2 is a graph schematically showing a relationship between a flow rate adopted by the apparatus of FIG. 1 and a cycle of measuring and sampling the flow rate. 2 is a time chart showing the flow rate measurement and integration operations performed by the apparatus of FIG. 1.

Explanation of reference numerals

Reference Signs List 4 flow meter 5 flow path 6 measuring member 8 flow rate detecting means 11 measuring unit 12 display unit 14 measuring unit 15 integrating unit 16 converting unit 17 total integrating unit 18 input unit 21 control unit

Claims (2)

Measuring means for repeating the measurement and sampling of the flow rate of the target fluid at a predetermined cycle, and integrating means for integrating the flow rate between the measured value previously sampled by the measuring means and the time until the next sampling time Converting means for converting the integrated amount integrated by the integrating means into a unit flow per unit time obtained by dividing the time from the previous sampling time to the next sampling time; and a unit time set at each sampling time. Each time elapses, a total integration means for repeatedly integrating the unit flow rate corresponding to the unit time to obtain a total integrated amount, and a flow rate every time the integrated amount integrated by the total integration means changes by a display unit. Display means to increase the display amount of the, the measuring means samples at a cycle according to the flow rate, and the conversion means with respect to the cycle Flowmeter and performing conversion unit flow rate in units of law time. When the sampling period of the measuring means exceeds the minimum period by a predetermined time, the flow rate is measured at a period shorter than the sampling period at that time, and it is monitored whether there is a change from the previously sampled measurement value and the sampling is performed first. 2. The flowmeter according to claim 1, wherein when the measured value changes from the measured value, a sampling cycle corresponding to the changed measured value is set, the unit flow rate is obtained, and integration is performed until the next sampling time.

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