JP2001228002A - Flowmeter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably measure a flow rate when measuring flow rate by detecting fluctuation information of a gas or a liquid having a flow rate fluctuation or a pressure fluctuation. SOLUTION: The sound wave transmitting / receiving device 1 is provided in a channel 24.
A pair of transmitting / receiving means 23 and 25, a repeating means 34 for repeatedly transmitting a signal from the transmitting / receiving means, and a timing means 27 for measuring a propagation time of a sound wave during repetition by the repeating means.
A flow rate detecting means 28 for detecting a flow rate based on the value of the time counting means 27, a pressure fluctuation detector 29 for detecting a fluid pressure fluctuation in the flow path, and a measurement control means 31 for controlling the respective means, Measurement monitoring means 35 for monitoring the abnormality of each means.
And As a result, the flow rate can be measured in accordance with the fluctuation and the abnormality can be quickly detected by the measurement monitoring means 35, so that the treatment at the time of the abnormality can be performed accurately, the measured value is stabilized, and the flow rate can be accurately measured. Reliability can be further improved.

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 of a liquid or a gas with high accuracy even when a flow rate fluctuation occurs.

[0002]

2. Description of the Related Art Conventionally, this type of flow meter is disclosed in
Japanese Patent Application Laid-Open No. 5006 and Japanese Patent Application Laid-Open No. 11-44563 have been known. Hereinafter, the configuration will be described with reference to FIGS.

As shown in FIG. 14, a sampling program 2 for reading a measured value from an analog flow sensor 1 for measuring a gas flow rate at every predetermined first sampling time,
A gas consumption calculation program 3 for calculating a gas consumption flow rate in a predetermined time, and an average value calculation for reading a measurement value of the analog flow sensor every second sampling time within the predetermined time during the first sampling time and calculating an average value thereof The program was composed of a program 4, a pressure fluctuation period estimation program 5 for estimating the period of pressure fluctuation from the output of the flow sensor, and a RAM 6 as a memory. Here, 7 is a ROM of a memory for storing the programs, and 8 is a CPU for executing the programs. With this configuration,
The measurement processing is performed so that the predetermined measurement time is at least one cycle of the oscillation cycle of the pump or a multiple of the cycle,
By averaging, even if a change occurs in the flow rate, the measured flow rate is hardly affected.

As shown in FIG. 15, a flow rate detecting means 9 for detecting a flow rate, a fluctuation detecting means 10 for detecting a fluctuation waveform of a fluid, and a measurement of the flow rate detecting means are performed near zero of an AC component of the fluctuation waveform. The configuration includes a pulsation measuring unit 11 to be started and a flow rate calculating unit 12 for processing a signal of the flow rate detecting unit. Here, 13 is a signal processing circuit, 14 is a clock circuit,
15 is a trigger circuit, 16 is a transmission circuit, 17 is a comparison circuit,
Reference numeral 18 denotes an amplification circuit, 19 denotes a switch, 20 denotes a measurement start signal circuit, 21 denotes a starting unit, and 22 denotes a flow path. With this configuration, the flow rate around the average of the fluctuation waveform is measured, and accurate flow rate measurement is performed in a short time.

[0005]

However, in the first reference of the prior art, the gas flow rate is measured using the average value, and a long time measurement is required to obtain a stable average value. There was a problem that instantaneous flow rate measurement was difficult.
Further, in the second reference, the method of measuring the flow rate is changed without pressure fluctuation, and there is a problem that two means of the pressure measuring means and the flow rate measuring means must be provided.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a pair of transmitting and receiving means provided in a flow path for transmitting and receiving a sound wave, and a repetitive means for repeating signal propagation of the transmitting and receiving means. A time measuring means for measuring a propagation time of a sound wave during repetition by the repeating means; a flow rate detecting means for detecting a flow rate based on a value of the time measuring means; and a fluctuation detecting means for detecting a fluid fluctuation in the flow path. And measurement control means for controlling each means, and measurement and monitoring means for monitoring an abnormality of each means.

According to the above invention, when there is a fluctuation in the flow in the flow path, the flow rate is measured in accordance with the fluctuation and the abnormality can be quickly detected by the measurement and monitoring means, so that the measure at the time of the abnormality can be accurately performed. The flow rate can be measured accurately, the flow rate can be measured accurately, and the reliability can be improved.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention provides a pair of transmitting and receiving means provided in a flow path for transmitting and receiving a sound wave, a repeating means for repeating the signal propagation of the transmitting and receiving means, and a circuit for repeating the transmission by the repeating means. Time measuring means for measuring the propagation time of the sound wave, a flow rate detecting means for detecting a flow rate based on the value of the time measuring means, a fluctuation detecting means for detecting a fluid fluctuation in the flow path, and a measurement for controlling the respective means. A control unit; and a measurement monitoring unit that monitors an abnormality of each of the units. If there is a change in the flow in the flow path, the flow rate is measured in accordance with the change, and the abnormality can be quickly detected by the measurement and monitoring means. The flow rate can be measured accurately and reliability can be improved.

A pair of transmission / reception means provided in the flow path for transmitting / receiving a sound wave, a repetition means for repeating signal propagation of the transmission / reception means, and a propagation time of the sound wave during the repetition by the repetition means. Time measuring means for measuring, flow rate detecting means for detecting a flow rate based on the value of the time measuring means, fluctuation detecting means for detecting fluid fluctuation in the flow path, measurement control means for controlling each of the means, After the instruction signal from the control means, a start signal instructing the start of sound wave transmission at the time of the first output signal of the fluctuation detecting means, and an end signal instructing the repetition of transmission and reception of sound waves at the time of the second output signal of the fluctuation detecting means. And a measuring and monitoring means for monitoring abnormalities of the start signal and the end signal. And when there is a fluctuation in the flow in the flow path,
Since the measurement can be performed in synchronization with the fluctuation cycle and the abnormality can be detected by the measurement monitoring means, the measurement value can be measured stably and the flow rate can be measured accurately. Reliability can be improved.

The fluctuation detecting means outputs a first output signal when the detection signal starts a cycle, and outputs a second output signal when the detection signal reaches one cycle. Then, the flow rate can be measured in units of one cycle by a signal in each cycle, and even in a state where the fluctuation occurs, the vertical fluctuation can be canceled, and the flow rate can be measured accurately.

[0011] Further, there is provided a measurement monitoring means for instructing the start of the transmission of the sound wave after a predetermined time when the start signal is not generated within a predetermined time after the instruction of the measurement control means. Then, even when there is no fluctuation and there is no start signal within a predetermined time, the flow rate can be measured at every predetermined time, and data loss can be prevented.

[0012] Further, when the start signal is not generated within a predetermined time after the instruction of the measurement control means, there is provided a measurement monitoring means for instructing the start of sound wave transmission after a predetermined time and performing measurement at a predetermined number of repetitions. Was. Then, even when there is no fluctuation and there is no start signal within a predetermined time, the flow rate can be measured at a predetermined number of repetitions every predetermined time and data loss can be prevented.

[0013] Further, a measurement monitoring means is provided which does not measure until the next instruction of the measurement control means when no start signal is generated within a predetermined time after the instruction of the measurement control means. Then, by waiting until the next measurement instruction, useless measurement can be stopped and power consumption can be reduced.

[0014] Further, there is provided a measurement monitoring means for terminating the reception of the sound wave when the end signal is not generated within a predetermined time after the start signal. Then, by forcibly terminating the measurement, the measurement does not stop waiting for the termination, and the process can proceed to the next process, and a stable measurement operation can be performed.

In addition, when no end signal is generated within a predetermined time after the start signal, a measurement monitoring means is provided for terminating the reception of the sound wave and outputting the start signal again. By forcibly terminating the measurement, the measurement is not stopped at the end of the measurement, and the measurement is performed again by outputting the start signal again, so that a stable measurement operation can be performed.

Further, the apparatus is provided with measurement monitoring means for terminating the reception of the sound wave and discarding the measurement data when no end signal is generated within a predetermined time after the start signal. If the measurement is not completed within the predetermined time, the data is determined as abnormal data, and the data is discarded, whereby the flow rate can be measured using only accurate data.

Further, a measurement monitoring means for terminating the reception of the sound wave and discarding the measurement data when the number of repetitions becomes equal to or more than a predetermined number is provided. When the number of repetitions is equal to or more than the predetermined number, the flow rate can be measured using only accurate data by discarding the data by determining that the data is abnormal.

Further, the apparatus is provided with a measurement monitoring means for discarding the measurement data when the number of repetitions is equal to or less than a predetermined number. When the number of repetitions is equal to or less than the predetermined number, discarding the data allows the flow rate to be measured using only accurate data.

When the number of repetitions is equal to or less than a predetermined number, the measurement data is discarded and a start signal is output again. When the number of repetitions is equal to or less than the predetermined number, by discarding the data, the flow rate can be measured using only the accurate data, and the re-measurement can be performed by outputting the start signal again, and the stable measurement can be performed. Measurement operation can be performed.

When the number of repetitions is equal to or less than a predetermined number, the measurement data is discarded and a start signal is output again, and the fluctuation detecting means outputs a second output signal when the second cycle is reached. Measurement monitoring means for continuing measurement until the end signal of the second cycle is provided. When the number of repetitions is equal to or less than a predetermined number, by discarding the data, the flow rate can be measured using only accurate data, and at the time of re-measurement, the cycle is doubled and the measurement is performed within the predetermined number of times. Can be performed and stable measurement can be performed.

Also, of the pair of transmitting / receiving means, the first number of repetitions at the time of measurement transmitted from one transmitting / receiving means and received by the other transmitting / receiving means, and the transmission / reception from the other transmitting / receiving means and one transmitting / receiving means Measurement monitoring means for comparing the second number of repetitions at the time of measurement to be received and outputting a start signal again when the difference between the two repetitions is a predetermined number or more is provided. And
When the number of repetitions is significantly different, remeasurement is performed, and measurement is performed in a state where the fluctuation period is stable, so that highly accurate flow rate measurement can be performed.

Also, of the pair of transmitting / receiving means, the first number of repetitions at the time of measurement transmitted from one transmitting / receiving means and received by the other transmitting / receiving means, and the transmission / reception from the other transmitting / receiving means and one transmitting / receiving means There is provided a repetition means for setting the second number of repetitions at the time of measurement to be received to be the same.
With the same number of repetitions, a predetermined flow rate measurement can be performed even when the fluctuation cycle is unstable.

Also, the number of times the start signal is output again is up to a predetermined number, and a measuring and monitoring means for monitoring such that the signal is not repeated forever is provided. By limiting the number of re-measurements, stable processing can be performed without infinite processing.

Also, the flow rate is measured from the reciprocal difference of the propagation time measured by repeating the transmission and reception of the ultrasonic wave a plurality of times. Then, by using ultrasonic waves, transmission and reception are possible without being affected by the fluctuation frequency in the flow path, and by measuring the flow rate from the reciprocal difference of the time when the propagation time is measured by repeating transmission and reception, the cycle of the cycle is obtained. Even a long fluctuation can be measured in one cycle unit, and a difference in propagation time due to the fluctuation can be canceled by the reciprocal difference.

[0025]

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

(Embodiment 1) FIG. 1 is a block diagram of a flow meter according to Embodiment 1 of the present invention. In FIG. 1, reference numeral 23 denotes a channel 2
4, a first piezoelectric vibrator as a first vibrating means of a transmitting / receiving means for transmitting and receiving ultrasonic waves; 25, a second piezoelectric vibrator as a second vibrating means of a transmitting / receiving means for transmitting and receiving ultrasonic waves; Is a changeover switch as a switching means for switching transmission and reception operations of the first piezoelectric vibrator and the second piezoelectric vibrator, and 27 is a propagation of a sound wave repeatedly transmitted and received by the first piezoelectric vibrator 23 and the second piezoelectric vibrator 25. A time measuring means for measuring time; 28, a flow rate detecting means for measuring a flow rate based on the value of the time measuring means; 29, a pressure fluctuation detector as a fluctuation detecting means for measuring a pressure fluctuation in the flow path 24; Synchronization pulse output means 31 as a fluctuation detecting means for converting the pressure signal of the detector 29 into a digital signal, and 31 is a measurement control means for instructing measurement in synchronization with the timing of the pressure fluctuation of the fluctuation detecting means. It is. Here, 32 is a transmitter of an ultrasonic signal transmitting / receiving means, 33 is a receiver of an ultrasonic signal transmitting / receiving means, 34 is a repeating means for repeatedly transmitting / receiving ultrasonic waves, and 35 is a monitor for abnormality of the measurement control means. It is a measurement monitoring means.

Next, the operation and operation will be described with reference to FIGS. In the flow path configured as shown in FIG.
When the time T1 for propagation from the piezoelectric vibrator 23 to the second piezoelectric vibrator 25 is measured, T1 = L / (C + Vcos)
θ). When the time T2 for propagation from the second piezoelectric vibrator 25 to the first piezoelectric vibrator 23 is measured,
2 = L / (C−Vcos θ). Here, V is the flow velocity in the flow channel, C is the speed of sound, and θ is the inclination angle. And T
By taking the reciprocal difference between 1 and T2 and transforming the equation, T1, T2
The flow velocity V is obtained from the following equation.

V = (L / 2 cos θ) · (1 / T1-1 / T2) Here, if there is a pressure fluctuation in the flow path, the flow velocity changes according to the pressure fluctuation. Therefore, assuming that the pressure fluctuating frequency f and the fluctuating flow velocity u are T1 and T2, T1 = L / (C + Vcos θ + u · sin (2πf)
t)) T2 = L / (C−Vcos θ−u · sin (2πft +
ψ)). Here, ψ is a time difference (phase difference) between the start of the T1 measurement and the start of the T2 measurement. Then, by taking the reciprocal difference between T1 and T2, 1 / T1-1 / T2 = (2Vcos θ + u · (sin
Since (2πft) + sin (2πft + ψ))) / L, when ψ = π, sin (2πft + ψ))
= −sin (2πft), and the influence of the fluctuation is cancelled. Therefore, assuming that V = (L / 2 cos θ) · (1 / T1-1 / T2), the flow velocity V can be measured even in the case of fluctuation, and the flow rate can be calculated in consideration of the cross-sectional area of the flow path and the like. . As described above, the measurement control unit that measures the flow rate while detecting the pressure fluctuation can accurately measure the flow rate without being affected by the pressure fluctuation by setting ψ = π. Although the above description has been given of one transmission / reception measurement, it is apparent that the integration time can be obtained in the same manner when the repeating time is measured by the repeating means 34 repeatedly.

Then, as shown in FIG. 3, the measurement control means 31 outputs a measurement start signal at a predetermined measurement time (for example, every two seconds), and sets a zero-cross point of the pressure fluctuation as a threshold value. Wait for a change in the output signal of the synchronization pulse output means. Then, when the output signal of the synchronizing pulse output means 30 outputs a falling signal of the output signal as the first output signal, measurement of the first clocking time T1 is started, and as the second output signal of the synchronizing pulse output means 30 The measurement of the propagation time is repeated until the rising signal of the output signal is output. In the next measurement, when the rising signal of the output signal as the first output signal of the synchronous pulse output means 30 is output, the measurement of the second time T2 is started, and as the second output signal of the synchronous pulse output means 30 The measurement of the propagation time is repeated until the falling signal of the output signal is output. Then, the flow rate detecting means 28 converts the time from the time T1, T2 of the time measuring means 27 to the flow rate and completes the flow rate measurement.

However, as shown in FIG. 4, the measurement control means 31 outputs a measurement start signal when a predetermined measurement time comes, but the measurement control means 31 waits for a predetermined time for a change in the output signal of the synchronous pulse output means. If no change occurs in the output signal of the synchronous pulse output means, a measurement start signal is automatically output and measurement is performed at a predetermined number of repetitions (for example, 256 times). For example,
When the measurement interval is 2 seconds and the frequency of pressure fluctuation occurs in the range of 10 Hz to 20 Hz, the predetermined time of the waiting time is
Although it can be set between 0.1 second and 2 seconds, it is desirable to set 1 second as the optimum value. The predetermined number of repetitions can be set from 2 to 512 times, and it is desirable to set an optimum value according to the frequency of pressure fluctuation.

As described above, even when the pressure does not fluctuate after the output of the measurement start signal, the measurement can be started after a predetermined time and the flow measurement can be performed whenever the flow measurement has to be performed. For example, a gas meter measures the presence or absence of a flow rate when an earthquake occurs.If a pressure fluctuation is awaited at that time, an automatic The flow rate can be measured appropriately, and an abnormal situation can be dealt with.

Although the fluctuation of the flow is explained by the fluctuation of the pressure in the flow passage, it is clear that the same effect can be obtained even when there is a fluctuation of the flow velocity by using the flow velocity fluctuation detecting means.

(Embodiment 2) FIG. 5 is a timing chart showing the operation of a flow meter according to Embodiment 2 of the present invention. Example 1
The difference from the first embodiment is that a measurement monitoring unit 35 that does not perform measurement until the next instruction from the measurement control unit when the start signal is not generated within a predetermined time after the instruction from the measurement control unit 31 is provided. The configuration is shown in FIG.

As shown in FIG. 5, the measurement control means 31
When a predetermined measurement time comes, a measurement start signal is output. If no change in the output signal of the synchronization pulse output unit appears even after waiting for a change in the output signal of the synchronization pulse output unit for a predetermined time, the measurement monitoring unit 35 performs measurement so that the standby of the synchronization pulse signal ends. The control unit is instructed to wait for the next measurement timing (for example, two seconds later). Here, when the measurement interval is 2 seconds and the frequency of the pressure fluctuation occurs in the range of 10 Hz to 20 Hz, the predetermined waiting time can be set from 0.1 second to 2 seconds.
It is desirable to set 1 second as the optimum value.

As described above, when the pressure does not change after the output of the measurement start signal, the standby is ended after a predetermined time and the flow rate measurement is not performed, so that the flow rate measurement with low accuracy can be avoided. FIG. 5 shows the timing at which the first propagation time T1 is measured. However, when the synchronization pulse is not generated when the second propagation time T2 is measured, T1 and T2 are measured.
Since the interval of the measurement time becomes abnormally long, the measurement accuracy decreases. It is possible to avoid such measurement in which the measurement accuracy is reduced. By waiting for the next measurement instruction, useless measurement can be stopped and power consumption can be reduced. For example, when a microcomputer that controls a security function is driven by a battery, such as a gas meter, the life can be extended by reducing the power consumption.

(Embodiment 3) FIG. 6 is a timing chart showing the operation of a flow meter according to Embodiment 3 of the present invention. Example 1
The difference is that when the end signal is not generated within a predetermined time after the start signal, the reception of the sound wave is ended, and when the end signal is not generated within the predetermined time, the reception of the sound wave is ended. Thus, the configuration is provided with the measurement monitoring means 35 for outputting the start signal again. The configuration is shown in FIG.

As shown in FIG. 6, the measurement control means 31
When a predetermined measurement time comes, a measurement start signal is output, and when the output signal of the synchronization pulse output means falls, the first output signal is detected and measurement is started. When the second output signal at which the output signal of the synchronous pulse output means falls does not appear even after waiting for a predetermined time, the standby for the synchronous pulse signal is terminated, and a start signal is output again to perform measurement. here,
When the measurement interval is 2 seconds and the frequency of pressure fluctuation occurs in the range of 10 Hz to 20 Hz, the predetermined time of the waiting time is
Although it can be set between 0.1 second and 2 seconds, it is desirable to set 1 second as the optimum value. This is because if it is 1 second, even if re-measurement is performed, the measurement can be completed by 2 seconds as the next measurement time. In this case, when the second output signal does not appear at the time of re-measurement, the process waits until the next measurement time.

As described above, when there is no change in the pressure after the start of the measurement, the standby is ended after a predetermined time and the flow measurement is not performed, so that an erroneous flow measurement can be avoided. Further, by supplementing the re-measurement, it is possible to prevent missing of data of the predetermined regular measurement, to smoothly perform the measurement processing such as averaging, and to improve the accuracy of the measured flow rate value. Furthermore, if the end of the measurement is not instructed, the time counting means and the like will make an erroneous measurement, and the measurement accuracy will decrease. It is possible to avoid such measurement in which the measurement accuracy is reduced.
Then, by forcibly terminating the measurement, the measurement does not stop waiting for the termination, and the process can proceed to the next process, and a stable measurement operation can be performed.

(Embodiment 4) FIG. 7 is a flowchart showing the operation of a flow meter according to Embodiment 4 of the present invention. The difference from the first embodiment is that, when the end signal is not generated within a predetermined time T after the start signal, the measurement is provided with the measurement monitoring means 35 which ends the reception of the sound wave and discards the measurement data. . The configuration is shown in FIG.

As shown in FIG. 7, after the first output signal is output, even if a predetermined time T (for example, 0.5 seconds) elapses, 1 is output.
When the second output signal indicating the end of the cycle is not generated, repetition of transmission / reception is ended and the measurement data up to that time is discarded. Then, after waiting for a predetermined time, the measurement is restarted.

As described above, when the measurement is not successfully performed, by discarding the data, only accurate data can be used, and a stable measurement operation can be performed. Further, there is no need to hold measurement data, and power consumption required for measurement can be reduced. Further, by managing the predetermined time T, it is possible to manage that a regular measurement cycle (for example, 2 seconds) is exceeded, and it is possible to perform measurement so that measurement timings do not overlap. Then, even when the propagation time of the ultrasonic wave changes due to a change in the temperature, it can be managed in the same predetermined time T.

(Embodiment 5) FIG. 8 is a flowchart showing the operation of a flow meter according to Embodiment 5 of the present invention. The difference from the first embodiment is that a configuration is provided in which a measurement monitoring unit 35 that terminates reception of a sound wave and discards measurement data when the number of repetitions becomes equal to or greater than a predetermined number N1. The configuration is shown in FIG.

As shown in FIG. 8, when the second output signal indicating the end of one cycle is not generated even after the first output signal is output and the number of times exceeds a predetermined number N1 (for example, 512 times), The repetition of transmission and reception was terminated, and the measurement data up to that point was discarded. Then, after waiting for a predetermined time, the measurement is restarted.

As described above, when the measurement is not successfully performed, by discarding the data, only accurate data can be used, and a stable measurement operation can be performed. Further, there is no need to hold measurement data, and power consumption required for measurement can be reduced. Further, by managing the number of repetitions, even when the propagation time of the ultrasonic wave changes due to a change in temperature, measurement can be performed regardless of the propagation time up to the limit of the number of repetitions.

(Embodiment 6) FIG. 9 is a flowchart showing the operation of a flow meter according to Embodiment 6 of the present invention. The difference from the first embodiment is that a measurement monitoring unit 35 for discarding measurement data when the number of repetitions is equal to or less than a predetermined number N2 is provided. The configuration provided with the measurement monitoring means 35 for outputting is provided. The configuration is shown in FIG.

As shown in FIG. 9, when the number of repetitions in a predetermined measurement performed based on the fluctuation cycle is equal to or less than a predetermined number N2 (for example, 100), the measurement data up to that time is discarded. Then, after waiting for a predetermined time, the measurement is restarted.

As described above, even if the measurement is performed normally, if the number of repetitions is equal to or less than the predetermined number, there is a possibility that the pressure fluctuation may not be accurately captured, and the measurement is not performed in one cycle. By discarding the data and performing the measurement again, a stable measurement operation can be performed. Further, there is no need to hold measurement data, and power consumption required for measurement can be reduced.

(Embodiment 7) FIG. 10 is a flowchart showing the operation of a flow meter according to Embodiment 7 of the present invention. The difference from the first embodiment is that when the number of repetitions is equal to or less than the predetermined number N2, the measurement data is discarded, the start signal is output again, and the synchronization pulse output means 30 as the fluctuation detection means is provided in the second cycle. A configuration is provided in which a second output signal is output when the signal has reached the current value, and the measurement monitoring means 35 continues the measurement until the end signal of the second cycle. The configuration is shown in FIG.

As shown in FIG. 10, in the predetermined measurement performed based on the fluctuation cycle, the number of repetitions is
At the time of (for example, 100 times) or less, the measurement data up to that time is discarded. Then, after waiting for a predetermined time,
When the signal of the synchronous pulse output means 30 reaches the second cycle, the second output signal is output, and the measurement that continues the measurement until the end signal of the second cycle is restarted.

As described above, even if the measurement is normally performed, if the number of repetitions is equal to or less than the predetermined number, there is a possibility that the pressure fluctuation may not be accurately captured, and the measurement is not performed in one cycle. By discarding the data and performing the measurement again, a stable measurement operation can be performed. Further, at the time of re-measurement, by performing measurement in two cycles, long-time measurement can be performed and measurement accuracy can be improved.

(Eighth Embodiment) FIG. 11 is a flowchart showing the operation of a flow meter according to an eighth embodiment of the present invention. The difference from the first embodiment is that, of the pair of transmitting and receiving means, the first number of repetitions N3 at the time of measurement, transmission from one of the transmitting and receiving means and reception by the other transmitting and receiving means, and transmission from the other transmitting and receiving means. The second repetition number N4 at the time of measurement received by the transmitting / receiving means is compared, and when the difference between the two repetition numbers is a predetermined number or more,
The configuration provided with the measurement monitoring means 35 for outputting the start signal again. The configuration is shown in FIG.

As shown in FIG. 11, when the difference between the first number of repetitions N3 and the second number of repetitions N4 is equal to or greater than a predetermined number M (for example, 10 times) in a predetermined measurement performed based on the fluctuation cycle, The measurement data up to is discarded and the measurement is restarted after waiting for a predetermined time.

As described above, even if the measurement is performed normally, when the difference between the first number of repetitions N3 and the second number of repetitions N4 is large, the pressure fluctuation is not accurately detected or the period of the pressure fluctuation fluctuates. Since the measurement has not been performed correctly, it is possible to perform a stable measurement operation by discarding the data and performing the measurement again.

(Embodiment 9) FIG. 12 is a flowchart showing the operation of a flow meter according to Embodiment 9 of the present invention. The difference from the first embodiment is that, of the pair of transmitting and receiving means, the first number of repetitions N3 at the time of measurement, transmission from one of the transmitting and receiving means and reception by the other transmitting and receiving means, and transmission from the other transmitting and receiving means. The second repetition number N4 at the time of measurement, which is received by the transmission / reception means, is provided with the repetition means 34 for setting the same number. The configuration is shown in FIG.

As shown in FIG. 12, in the predetermined measurement performed based on the fluctuation cycle, the second repetition number is performed at the same repetition number as the first repetition number N3. By performing the second measurement at the first repetition number N3, the difference from the true value can be measured without greatly differentiating.

As described above, the flow rate can be measured even when the periodic fluctuation of the pressure fluctuation is severe. For example, in the case of a gas meter, there is a time when the flow rate measurement for security is necessary.
By performing such a measurement, it can be instantaneously determined whether the flow rate is near the predetermined flow rate.

(Embodiment 10) FIG. 13 shows Embodiment 1 of the present invention.
5 is a flowchart showing the operation of a flow meter of zero. The difference from the first embodiment is that the number of times that the start signal is output again is up to the predetermined number C, and the configuration is provided with the measurement monitoring means 35 for monitoring so as not to repeat forever. The configuration is shown in FIG.

As shown in FIG. 13, when the measurement based on the pressure fluctuation fails and the measurement is performed again, the number C of the re-measurement is limited (for example, up to two times).
Stable flow measurement can be performed without the processing continuing indefinitely.

[0059]

As apparent from the above description, the flow meter according to the present invention has the following advantages.

A pair of transmission / reception means provided in the flow path for transmitting / receiving a sound wave, a repetition means for repeating the signal propagation of the transmission / reception means, and measuring a propagation time of the sound wave during the repetition by the repetition means. Time-measuring means, flow-rate detecting means for detecting a flow rate based on the value of the time-measuring means, fluctuation detecting means for detecting a fluid fluctuation in the flow path, measurement control means for controlling each of the means, By providing measurement and monitoring means for monitoring abnormalities, if there is a fluctuation in the flow in the flow path, the flow rate can be measured in accordance with the fluctuation, and the abnormality can be quickly detected by the measurement and monitoring means. Can be performed accurately, the measured value is stable, the flow rate can be measured accurately, and the reliability can be improved.

Also, a pair of transmitting / receiving means provided in the flow path for transmitting / receiving a sound wave, a repetition means for repeating the signal propagation of the transmission / reception means, and a propagation time of the sound wave during the repetition by the repetition means. Time measuring means for measuring, flow rate detecting means for detecting a flow rate based on the value of the time measuring means, fluctuation detecting means for detecting fluid fluctuation in the flow path, measurement control means for controlling each of the means, After the instruction signal from the control means, a start signal instructing the start of sound wave transmission at the time of the first output signal of the fluctuation detecting means, and an end signal instructing the repetition of transmission and reception of sound waves at the time of the second output signal of the fluctuation detecting means. And the measurement and monitoring means for monitoring the abnormality of the start signal and the end signal. When there is a change in the flow in the flow path, the flow is measured in synchronization with the fluctuation cycle, and the abnormality is measured by the measurement and monitoring means. detection Since it is Rukoto, the measured value can be measured stably and accurately the flow rate, and abnormal action to be precisely line, it is possible to improve the reliability of the measurement flow rate value.

Further, the fluctuation detecting means outputs the first output signal when the detection signal starts a cycle and outputs the second output signal when the detection signal reaches one cycle, so that the signal is output once every cycle. The flow rate can be measured in a cycle unit, and even in a state where the fluctuation occurs, the vertical fluctuation can be canceled, and the flow rate can be measured accurately.

Further, when the start signal is not generated within a predetermined time after the instruction of the measurement control means, the measurement monitoring means for instructing the start of the transmission of the sound wave after the predetermined time is provided. Even when there is no start signal, the flow rate can be measured at predetermined time intervals and data loss can be prevented.

Further, when the start signal is not generated within a predetermined time after the instruction of the measurement control means, a measurement monitoring means for instructing the start of transmission of a sound wave after a predetermined time and performing measurement at a predetermined number of repetitions is provided. Thus, even when there is no fluctuation and there is no start signal within a predetermined time, the flow rate can be measured at a predetermined number of repetitions every predetermined time and data loss can be prevented.

Further, when the start signal is not generated within a predetermined time after the instruction of the measurement control means, the measurement monitoring means which does not perform the measurement until the instruction of the next measurement control means is provided.
By waiting until the next measurement instruction, useless measurement can be stopped and power consumption can be reduced.

Further, when the end signal is not generated within a predetermined time after the start signal, the measurement monitoring means for terminating the reception of the sound wave is provided. The next process can be performed without performing, and a stable measurement operation can be performed.

When the end signal is not generated within a predetermined time after the start signal, the reception of the sound wave is terminated, and the measurement and monitoring means for outputting the start signal again is provided, thereby forcibly terminating the operation. As a result, the measurement does not stop at the end waiting, and the measurement is performed again by outputting the start signal again, so that a stable measurement operation can be performed.

When the end signal is not generated within a predetermined time after the start signal, the reception of the sound wave is terminated and the measurement monitoring means for discarding the measurement data is provided. When there is no such data, it is determined that the data is abnormal, and the data is discarded, whereby the flow rate can be measured using only accurate data.

Also, by providing measurement monitoring means for terminating the reception of the sound wave and discarding the measurement data when the number of repetitions becomes a predetermined number or more, when the number of repetitions is more than the predetermined number, abnormal data is generated. By judging and discarding the data, the flow rate can be measured using only accurate data.

When the number of repetitions is less than a predetermined number, measurement monitoring means for discarding measurement data is provided. When the number of repetitions is less than a predetermined number, data is discarded to use only accurate data. To measure the flow rate.

When the number of repetitions is equal to or less than a predetermined number, the measurement data is discarded and a start signal is output again,
When the number of repetitions is equal to or less than a predetermined number, discarding the data enables the flow rate measurement to be performed using only accurate data, and outputs a start signal again to perform re-measurement, thereby achieving stable measurement. The actions can be done.

When the number of repetitions is equal to or less than a predetermined number, the measurement data is discarded and a start signal is output again, and the fluctuation detecting means outputs a second output signal when the second cycle is reached. By providing a measurement monitoring unit that continues measurement until the end signal of the second cycle, when the number of repetitions is equal to or less than a predetermined number, the data can be discarded to perform flow measurement using only accurate data. At the same time, at the time of re-measurement, the cycle can be doubled so that the measurement can be performed within a predetermined number of times, so that stable measurement can be performed.

Also, of the pair of transmission / reception means, the first number of repetitions at the time of measurement transmitted from one transmission / reception means and received by the other transmission / reception means, and the transmission / reception from the other transmission / reception means is performed by one transmission / reception means. The second repetition number at the time of measurement to be received is compared, and when the difference between the two repetition numbers is equal to or more than a predetermined number, a measurement monitoring unit that outputs a start signal again is provided. Thus, the flow rate can be measured with high accuracy by performing the measurement in a state where the fluctuation period is stable.

Also, of the pair of transmitting / receiving means, the first number of repetitions at the time of measurement transmitted from one transmitting / receiving means and received by the other transmitting / receiving means, and the transmission / reception from the other transmitting / receiving means and one transmitting / receiving means By providing a repetition means for setting the second number of repetitions at the time of measurement to be received to be the same, it is possible to perform a predetermined flow rate measurement even when the fluctuation cycle is unstable by setting the same number of repetitions. it can.

Also, the number of times the start signal is output again is up to a predetermined number, and the measurement monitoring means for monitoring such that the signal is not repeated forever is provided. Stable flow measurement can be performed without any occurrence.

Further, by measuring the flow rate from the reciprocal difference of the propagation time measured by repeating the transmission and reception of the ultrasonic wave a plurality of times, transmission and reception can be performed without being affected by the fluctuation frequency in the flow path. By measuring the flow rate from the reciprocal difference of the time when the propagation time was measured, even a long-period fluctuation can be measured in one cycle unit, and the difference in the propagation time due to the fluctuation can be offset by the reciprocal difference.

[Brief description of the drawings]

FIG. 1 is a block diagram of a flow meter according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing the principle of the flow meter.

FIG. 3 is a timing chart showing the operation of the flow meter.

FIG. 4 is another timing chart showing the operation of the flow meter.

FIG. 5 is a timing chart showing the operation of the flow meter according to the second embodiment of the present invention.

FIG. 6 is a timing chart showing the operation of the flow meter according to the third embodiment of the present invention.

FIG. 7 is a flowchart showing the operation of the flow meter according to the fourth embodiment of the present invention.

FIG. 8 is a flowchart showing the operation of the flow meter according to the fifth embodiment of the present invention.

FIG. 9 is a flowchart showing the operation of the flow meter according to the sixth embodiment of the present invention.

FIG. 10 is a flowchart showing the operation of the flow meter according to the seventh embodiment of the present invention.

FIG. 11 is a flowchart showing the operation of the flow meter according to the eighth embodiment of the present invention.

FIG. 12 is a flowchart showing the operation of the flow meter according to the ninth embodiment of the present invention.

FIG. 13 is a flowchart showing the operation of the flow meter according to the tenth embodiment of the present invention.

FIG. 14 is a block diagram showing a conventional flow meter.

FIG. 15 is a block diagram showing another conventional flow meter.

[Explanation of symbols]

 23 first piezoelectric vibrator (transmitting / receiving means, first vibrating means) 24 flow path 25 second piezoelectric vibrator (transmitting / receiving means, second vibrating means) 26 switching means 27 clocking means 28 flow rate detecting means 29 pressure fluctuation detector (Fluctuation detecting means) 30 synchronization pulse output means (fluctuation detecting means) 31 measurement control means 34 repetition means 35 measurement monitoring means

Claims (17)

[Claims] 1. A pair of transmission / reception means provided in a flow path for transmitting and receiving a sound wave, a repetition means for repeating signal propagation of the transmission / reception means, and a propagation time of the sound wave during repetition by the repetition means. Time measuring means for measuring, flow rate detecting means for detecting a flow rate based on the value of the time measuring means, fluctuation detecting means for detecting fluid fluctuation in the flow path, measurement control means for controlling each of the means, A flow meter including a measurement monitoring means for monitoring an abnormality of the means. 2. A pair of transmitting / receiving means provided in a flow path for transmitting / receiving a sound wave, a repetition means for repeating signal propagation of the transmission / reception means, and a propagation time of the sound wave during repetition by the repetition means. Time measuring means for measuring, flow rate detecting means for detecting a flow rate based on the value of the time measuring means, fluctuation detecting means for detecting fluid fluctuation in the flow path, measurement control means for controlling each of the means, After the measurement instruction signal from the control means, a start signal for instructing the start of transmission of sound waves at the time of the first output signal of the fluctuation detection means, and an end for instructing repetition of transmission and reception of sound waves at the time of the second output signal of the fluctuation detection means. A flowmeter comprising: a signal; and a measurement monitoring unit that monitors an abnormality of the start signal and the end signal. 3. The fluctuation detecting means outputs a first output signal when the detection signal starts a cycle, and outputs a second output signal when the detection signal reaches one cycle.
3. The flow meter according to claim 1, which outputs an output signal. 4. The apparatus according to claim 1, further comprising a measurement monitoring means for instructing a start of transmission of a sound wave after a predetermined time when no start signal is generated within a predetermined time after the instruction from the measurement control means. The flowmeter according to claim 1. 5. A measurement monitoring means for instructing a start of transmission of a sound wave after a predetermined time when no start signal is generated within a predetermined time after an instruction from the measurement control means, and performing measurement at a predetermined number of repetitions. The flowmeter according to claim 4. 6. A method according to claim 1, further comprising the step of: when no start signal is generated within a predetermined time after the instruction from the measurement control means, does not perform measurement until the next instruction from the measurement control means.
The flowmeter according to any one of claims 1 to 4. 7. The flow meter according to claim 1, further comprising a measurement monitoring means for ending reception of the sound wave when no end signal is generated within a predetermined time after the start signal. 8. A measurement monitoring means for terminating reception of a sound wave and outputting a start signal again when no end signal is generated within a predetermined time after the start signal.
Flowmeter as described. 9. A measurement monitoring means for terminating the reception of sound waves and discarding measurement data when no end signal is generated within a predetermined time after the start signal. 7. The flow meter according to 7. 10. The flowmeter according to claim 1, further comprising a measurement monitoring means for terminating the reception of the sound wave and discarding the measurement data when the number of repetitions becomes equal to or more than a predetermined number. 11. The flowmeter according to claim 1, further comprising a measurement monitoring means for discarding measurement data when the number of repetitions is equal to or less than a predetermined number. 12. The flowmeter according to claim 1, further comprising a measurement monitoring means for discarding the measurement data and outputting a start signal again when the number of repetitions is equal to or less than a predetermined number. 13. When the number of repetitions is equal to or less than a predetermined number, the measurement data is discarded and a start signal is output again, and the fluctuation detecting means outputs a second output signal when the second cycle is reached. The flowmeter according to any one of claims 1 to 3, further comprising a measurement monitoring unit that continues measurement until an end signal of the second cycle. 14. A first number of repetitions at the time of measurement in which transmission is performed from one of the transmission / reception means and reception is performed by the other transmission / reception means of the pair of transmission / reception means, and transmission is performed by the other transmission / reception means and one of the transmission / reception means performs transmission. 4. A measurement monitoring means for comparing a second number of repetitions at the time of measurement to be received and outputting a start signal again when a difference between the two repetitions is a predetermined number or more.
The flowmeter according to any one of claims 1 to 4. 15. A first number of repetitions at the time of measurement transmitted from one transmitting / receiving means and received by the other transmitting / receiving means of the pair of transmitting / receiving means, and transmission from the other transmitting / receiving means and one transmitting / receiving means. The flowmeter according to any one of claims 1 to 3, further comprising a repetition unit that sets the second number of repetitions at the time of measurement to be received to be the same. 16. The flow meter according to claim 1, further comprising a measurement monitoring means for monitoring the number of times the start signal is output again up to a predetermined number of times and for preventing repetition. 17. A flow rate is measured from a reciprocal difference of a propagation time measured by repeating transmission and reception of ultrasonic waves a plurality of times.
7. The flow meter according to any one of 6 above.