JP2004271490A - Flowmeter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a flowmeter for measuring the flow rate of a fluid such as air, gas or water by use of ultrasonic waves, which can attain both a low power consumption and a high precise measurement. <P>SOLUTION: This flowmeter comprises a high-precision flow measuring means, a low-power consumption flow measuring means, and a measurement switching means 29 for switching the flow measuring means depending on the measured flow rate of at least one of the high-precision flow measuring means and the low-power consumption flow measuring means. According to such a structure, a plurality of flow measuring means can be switchingly used, and a precise flow measurement and a flow measurement with low power consumption can be realized compatibly. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an ultrasonic flowmeter that measures the flow rate of a fluid such as air, gas, or water using ultrasonic waves.
[0002]
[Prior art]
Conventionally, an ultrasonic flow meter of this type includes an ultrasonic flow velocity measuring means 4 provided by providing a pair of acoustic transducers 2 and 3 provided in a flow path 1 as shown in FIG. A measurement interval changing unit 5 for changing a measurement interval of the measurement unit 4, a pressure detection unit 6 for detecting a pressure in the flow path, a pressure determination unit 7, a determination value adjustment unit 8, and a pulse wave detection unit 9 Be composed.
[0003]
Here, 10 is a random time generating means, 11 is a flow rate measuring means, 12 is a flow rate integrating means, 13 is a display means, 14 is a shutoff valve means, and 15 is a valve control means (for example, see Patent Document 1).
[0004]
In the above configuration, the pulse wave of the fluid in the flow path is monitored, and when a pulse wave larger than a predetermined determination value is detected, the measurement interval is shortened to increase the measurement accuracy and measure the flow velocity. Things.
[0005]
Further, as shown in FIG. 10, the one configured of a measured flow rate unit 16, a flow rate value integration unit 17, a first buffer 18, a second buffer 19, and a flow rate integration value storage unit 20 is also available. It is known (for example, see Patent Document 2).
[0006]
In the above configuration, the flow rate measurement error caused by the generation of the pulsation in the fluid is eliminated by using the first buffer 3 and the second buffer 4.
[0007]
That is, in the first buffer 3, the flow rate value sent from the flow rate measuring section 1 is integrated and the counter value is incremented. When the integrated value reaches a predetermined integration carry threshold or more, the flow rate integration is performed. The value is counted up by one unit, and the value of the remainder exceeding the accumulated carry threshold at that time is rounded down to reset the counter value to zero. The value of the truncated remainder is held by the second buffer 4 so that it can be integrated, and is reflected at a predetermined timing on the count-up of the integrated flow value and added.
[0008]
Therefore, even if a flow value is generated due to pulsation, the first buffer absorbs the flow value and does not immediately count up one unit amount, so that a flow measurement error at the time of pulsation can be absorbed.
[0009]
[Patent Document 1]
JP-A-11-258018
[Patent Document 2]
JP 2001-349752 A
[0010]
[Problems to be solved by the invention]
However, in the above-described conventional configuration, there is a problem that when the measurement is performed with the measurement interval shortened, power consumption used for the measurement increases, and when the battery is used, the device cannot withstand long-time use.
[0011]
In addition, in the buffer method, the problem that the counting up of the integrated flow rate is delayed and the value of the second buffer in which only the residual value remains are finally added, so errors due to pulsation are added. As a result, there is a problem that the accumulated error cannot be eliminated and the accuracy deteriorates.
[0012]
An object of the present invention is to solve such a conventional problem, and an object of the present invention is to provide a flowmeter with improved measurement accuracy and reduced power consumption.
[0013]
[Means for Solving the Problems]
The present invention, in order to solve the above problems, high-precision flow measurement means, low power consumption flow measurement means, the flow rate of at least one of the high-precision flow measurement means and the low power consumption flow measurement means flow measurement means And a measurement switching means for switching the flow measurement means.
[0014]
According to the above invention, it is possible to achieve both high-accuracy flow measurement and low-power-consumption flow measurement by switching and using a plurality of flow measurement units.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
The embodiment of the present invention is a high-precision flow rate measuring means, a low power consumption flow rate measuring means, the high-precision flow rate measuring means and the low power consumption flow rate measuring means at least one of the flow rate measurement means the flow rate. It is provided with a measurement switching means for switching the measurement means, and can be used by switching a plurality of flow measurement means, thereby realizing both high precision flow measurement and low power consumption flow measurement. .
[0016]
The high-precision flow rate measuring means is provided in a flow path, a pair of sound wave transmitting and receiving means for transmitting and receiving a sound wave, a repeating means for repeatedly transmitting and receiving the sound wave by the sound wave transmitting and receiving means, and a sound wave while being repeated by the repeating means. A time measuring means for measuring the propagation time, a flow rate detecting means for detecting a flow rate based on the value of the time measuring means, and a repetition number changing means for changing the repetition number of the repetition means, wherein the repetition number changing means , The number of repetitions is increased to perform high-precision flow measurement. By increasing the number of repetitions, the measurement time can be lengthened, so that measurement variation is reduced and measurement accuracy can be improved. .
[0017]
The low-power-consumption flow rate measuring means is provided in the flow path, and transmits and receives a sound wave. A pair of sound wave transmitting and receiving means, a repeating means for repeatedly transmitting and receiving sound waves by the sound wave transmitting and receiving means, A timer for measuring the propagation time of the sound wave; a flow rate detector for detecting a flow rate based on the value of the timer; and a repetition number changing means for changing the number of repetitions of the repetition means. The low power consumption flow rate measurement is performed by reducing the number of repetitions by means. By reducing the number of repetitions, the measurement time is shortened and the power consumption can be reduced.
[0018]
In addition, the first propagation time measurement when transmission and reception from the upstream side to the downstream side are repeatedly performed, and the second propagation time measurement when transmission and reception from the downstream side to the upstream side are repeatedly performed are one measurement unit. A repetition means, a measurement repetition means for repeating the measurement of the transmission / reception repetition means at least once or more, a total first propagation time and a total second propagation time when the transmission / reception repetition means and the measurement repetition means are repeated. A flow rate detection means for detecting a flow rate from a propagation time, and a high precision flow rate measurement means and a low power consumption flow rate measurement means are realized by changing the number of transmission / reception repetitions of the transmission / reception repetition means and the number of measurement repetitions of the measurement repetition means. By changing the number of repetitions of transmission and reception and the number of repetitions of measurement, it is possible to select and measure the accuracy and power consumption suitable for the measured flow rate, and to measure the flow rate fluctuation. Periodically occurs Also it is possible to realize a measurement cycle, or measurement with high accuracy can be timed to measure the measurement cycle matched removed from the pulse period during pulsations.
[0019]
A change detecting means for detecting a change in the flow rate from the measurement value of the low power consumption flow rate measuring means; and a measurement switch for switching the flow rate measuring means so as to measure by the high precision flow measuring means when the change detecting means detects the change. When the flow rate fluctuates, high-precision flow rate measurement can be stably performed by measuring the flow rate with the high-precision flow rate measurement means.
[0020]
Further, a flow rate determining means for determining a flow rate range from a measurement value of the high-precision flow rate measuring means, and when the flow rate determining means determines that the flow rate is small, the flow rate measurement by the high-precision flow rate measuring means is continued, and the flow rate determining means is When it is determined that the flow rate is large, the low power consumption flow rate measurement means is equipped with a measurement switching means for switching the flow rate measurement means. By measuring the measurement means by switching the flow rate range, the accuracy and power consumption suitable for the flow rate value are measured. , And wasteful power consumption can be suppressed.
[0021]
A flow rate integrating means for integrating the instantaneous flow rate value measured by the flow rate measuring means for a predetermined time; and a measurement switching means for switching to a high-precision flow rate measuring means when the integrated value of the flow rate integrating means becomes equal to or more than a predetermined flow rate value. When an integrated flow rate equal to or more than a predetermined flow rate value is generated, high-precision flow measurement means can measure whether the integrated value is a correct value, and update the correct integrated value. Therefore, a highly accurate flowmeter can be obtained.
[0022]
Further, it is provided with a flow rate abnormality determining means for determining whether or not the integrated flow value is normal based on the flow value measured by the high-precision flow measuring means, and can determine whether the integrated value is a correct value, Since the correct integrated value can be updated, a highly accurate flowmeter can be obtained.
[0023]
Also provided is a flow rate integrating means for clearing the integrated flow rate value when the integrated flow rate value does not exceed the predetermined flow rate even if the integrated flow value does not exceed the predetermined flow rate within a predetermined time. Since the value can be cleared and restarted, a high-accuracy flow rate measurement can be realized without accumulation of errors.
[0024]
Further, when the flow rate abnormality determination means determines that the flow rate is not normal, the flow rate abnormality determination means includes a flow rate integration means for clearing the integrated flow rate value and a flow rate storage means for storing the integrated flow rate value before clearing. By providing a flow rate storage unit that stores the flow rate values of the above, the accumulation of minute flow rates can be continued and accumulated for a long time. Thereby, highly accurate flow rate measurement can be realized.
[0025]
In addition, a flow rate display means for displaying the integrated flow rate is provided, and if the unit of the least significant digit of the flow rate display means is a predetermined flow rate, the least significant digit of the display means is set to the minimum unit, thereby temporarily causing an error. Since the measurement does not appear on the display even when the measurement is performed, erroneous recognition and erroneous recording can be prevented without being externally known.
[0026]
If the predetermined flow rate is one liter, a marginal flow rate of one liter can be provided, and temporary erroneous measurement can be absorbed.
[0027]
If the predetermined time is 1 minute or more and 12 minutes is optimal, the flow rate per hour can be provided with a surplus flow rate of 5 liters, and temporary erroneous measurement can be absorbed.
[0028]
In addition, if the measurement abnormality determination means for determining an abnormality based on the predetermined time, the integrated flow rate value, and the number of times the measurement method has been changed, and a warning display means for displaying an abnormality warning when the measurement abnormality determination means determines an abnormality, When the switching of the means frequently occurs, the abnormality can be notified by the measurement abnormality determining means and the warning means, and the abnormality such as the occurrence of pulsation can be found at an early stage.
[0029]
Since the battery is used as a power source, the battery can be used as a flowmeter used outdoors. Since the battery is provided with a low-power-consumption flow rate measuring means, a long life can be obtained even if a battery is used.
[0030]
【Example】
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0031]
(Example 1)
In FIG. 1, reference numeral 21 denotes a flow path for flowing a fluid, 22 denotes a sound wave transmitting / receiving means provided upstream of the flow path for transmitting / receiving ultrasonic waves, and 23 denotes a sound wave transmitting / receiving means provided downstream of the flow path for transmitting / receiving ultrasonic waves. Sound wave transmitting and receiving means, 24 is a repeating means for repeatedly transmitting and receiving sound waves, 25 is a time measuring means for measuring the propagation time of the sound wave repeatedly performed by the repeating means 24, and 26 is measured by the time measuring means 25 It is a flow rate detecting means for detecting a flow rate based on time information.
[0032]
Reference numeral 27 denotes a repetition number changing means for changing the number of repetitions of transmission and reception of sound waves, and reference numeral 28 denotes an ultrasonic flow rate measurement means for changing the number of repetitions each time according to predetermined conditions.
[0033]
The ultrasonic flow rate measuring means 28 realizes a high-precision flow rate measuring means by increasing the number of repetitions by the repetition number changing means 27, and realizes a low power consumption flow rate measuring means by decreasing the number of repetitions. The means for performing the measurement switching of the measuring means is the measurement switching means 29.
[0034]
Here, 30 is a fluctuation detecting means, 31 is a flow rate determining means, 32 is a flow rate integrating means, 33 is a flow rate abnormality determining means, 34 is a warning display means, 35 is a battery, 36 is a flow rate storage means, 37 is a flow rate display means, 38 is a measurement abnormality determining means.
[0035]
The measurement principle of the flowmeter having the above configuration will be described.
[0036]
When the propagation time T1 during which the sound wave propagates from the sound wave transmission / reception means 22 on the upstream side of the flow channel shown in FIG. 1 to the sound wave transmission / reception means 23 on the downstream side is measured, the propagation time T1 is represented by the equation (1).
[0037]
T1 = L / (C + Vcosθ) (1)
Also, when the propagation time T2 propagating from the downstream sound wave transmitting / receiving means 23 toward the upstream sound wave transmitting / receiving means 22 is measured, the propagation time T2 is as shown in Expression (2).
[0038]
T2 = L / (C−Vcos θ) (2)
Here, V is the flow velocity in the flow path, L is the distance between the sound wave transmitting / receiving means, θ is the angle of the sound wave transmitting / receiving means facing the flow path, and C is the sound speed.
[0039]
Then, by taking the difference between the reciprocals of T1 and T2 and transforming the equation, the flow velocity V can be obtained from T1 and T2 as in equation (3).
[0040]
V = (L / 2 cos θ) · (1 / T1-1 / T2) (3)
The flow rate Q can be calculated in consideration of the flow velocity V and the cross-sectional area of the flow path. Although the above description has been given of one transmission / reception measurement, it is apparent that the flow velocity V can be more accurately obtained by obtaining the integrated propagation time by a method of repeatedly measuring the propagation time by the repeating means 24. Will.
[0041]
However, this measurement is based on the condition that the flow velocity V1 at the time of transmission from the upstream side is the same as the flow velocity V2 at the time of transmission from the downstream side. Actually, there is a case where a flow rate fluctuation occurs like a pulsation. If there is a fluctuation in the flow velocity as shown in FIG. 2, if the measurement time is short, the average flow velocity V1 when measuring the propagation time from the upstream side measures the propagation time from the downstream side. Does not become the same as the average flow velocity V2, and a measurement error occurs.
[0042]
Therefore, as shown in FIG. 3, by increasing the number of repetitions and setting the measurement range to at least one cycle of fluctuation, the flow velocities are averaged and the propagation time is measured, so that the flow velocities V1 and V2 become similar. , Accuracy can be improved and maintained. A method using this principle is a high-accuracy flow rate measuring means realized by increasing the number of repetitions.
[0043]
Also, it is clear that the power consumption used for processing is reduced when the number of repetitions is small because the operation time is short. A measurement method for reducing the power consumption by reducing the number of repetitions is the low power consumption flow rate measurement unit.
[0044]
Next, the flow of the operation will be described with reference to the flowcharts shown in FIGS. As shown in FIG. 4, the flow measurement is usually performed in a low power consumption mode by a low power consumption flow measurement unit (STEP 10).
[0045]
Then, a fluctuation in flow rate is determined by the fluctuation detecting means 30 from the measured instantaneous flow rate value (STEP 11). If there is no fluctuation in the flow rate, the flow rate measurement is continuously performed in the low power consumption mode (STEP 10) through the flow rate integrating process (STEP 12).
[0046]
Here, the fluctuation detecting means 30 (STEP 11) will be described. For example, the fluctuation detecting means 30 obtains a difference (Qmax-Qmin) between the maximum flow rate value Qmax within a predetermined time and the minimum flow rate value Qmin within a predetermined time from the instantaneous flow rate value detected by the flow rate detecting means 26. Detect fluctuations.
[0047]
When the flow rate fluctuation (Qmax-Qmin) is 10 liters / hour or more as a predetermined flow rate, it is detected that there is fluctuation, and when the flow rate fluctuation is less than 10 liters / hour, the fluctuation detecting means 30 detects that there is no fluctuation. Detect it.
[0048]
Next, when the fluctuation is detected by the fluctuation detecting means 30, the flow rate is determined by the flow rate determining means 31 (STEP 13).
[0049]
When the flow rate determination unit 31 determines that the flow rate range is a large flow rate range (for example, 3000 liters / hour or more), the number of repetitions is reduced to an optimal minimum number (for example, from 8 to 128 times, and optimally 64 times) to reduce the number of repetitions. Measure in power consumption mode.
[0050]
When the flow rate determining means 31 determines that the flow rate range is a small flow rate range (for example, less than 3000 liters /), the number of repetitions is increased to an optimum number (for example, 64 to 512 times, and optimally 252 times), and the high precision flow rate is increased. Measurement can be continuously performed in the high-accuracy measurement mode as a measuring means (STEP 14).
[0051]
Even in the high-accuracy measurement mode, the fluctuation detection (STEP 11) is repeatedly performed. When the fluctuation stops, the flow returns to the low power consumption measurement mode (STEP 10) through the flow rate integration processing (STEP 12).
[0052]
In addition, when it is determined that the flow rate is in the large flow rate range and the measurement is performed in the low power consumption mode from the beginning, the number of repetitions is not changed.
[0053]
Then, the flow rate values measured in the respective measurement modes are integrated by the flow rate integrating means 32.
[0054]
FIG. 5 shows a flowchart of the integration process. The integration process determines whether or not the flow rate increase within a predetermined time period has reached a predetermined flow rate value (eg, a predetermined flow rate of 1 liter or more) within a predetermined time period (eg, a predetermined time period of 12 minutes) (STEP 20). The measurement is performed in the high-accuracy measurement mode (STEP 21).
[0055]
If it is less than the predetermined flow value, the integrated value within the predetermined time is cleared (STEP 22), it is determined whether there is any abnormality in the measurement (STEP 23), and the process returns to the measurement mode (STEP 24).
[0056]
As a result, it is possible to prevent the count-up of the integrated flow value due to the measurement error value at the time of flow fluctuation such as pulsation or the integration error of the minute flow value smaller than the measurement resolution.
[0057]
In addition, the accumulated integrated value and the instantaneous flow rate value newly measured in the high-accuracy measurement mode are converted and compared per the same predetermined time, and the flow rate abnormality determining means 33 determines whether or not the integrated value is correct. A determination is made (STEP 25).
[0058]
When it is determined that there is no abnormality, the integrated value is added (STEP 26), and the process returns to the measurement mode (STEP 24).
[0059]
However, when it is determined that there is an abnormality, the current flow value is stored in the storage means (STEP 27), and the flow value and the integrated value are cleared (STEP 28).
[0060]
The warning display means 34 of the flow meter displays a warning of abnormality (STEP 29), and returns to the high-accuracy measurement mode (STEP 30).
[0061]
That is, by storing the integrated value per predetermined time before clearing in the flow rate storage means 36, the flow rate value can be stored in the storage means while being added each time an abnormality is determined, It is possible to know the integrated flow rate at the time of abnormality.
[0062]
For example, if the integrated value of this storage means converges to zero, it is considered that the abnormal phenomenon has occurred at random and is considered to be an error due to the determination in a short time in processing. You can learn that there are few future problems.
[0063]
For example, if the measurement is performed once every two seconds, the flow rate exceeding one liter in one measurement is 1800 liters / hour.
[0064]
Normally, such a large flow rate does not flow at once, so that measurement is repeated twice or three times before exceeding the integrated flow rate of one liter. In the case of a random flow such as a pulsating flow, the flow rate on the positive side and the flow rate on the negative side are repeated, and converge to zero on average.
[0065]
Although the measurement timing is once every two seconds, since the timing is slightly randomized and measured, the flow rate on the plus side and the minus side is approximately repeated. Therefore, if the integration is continued, it should normally converge to zero.
[0066]
However, if the integrated value of the flow rate storage means 36 does not converge to zero, it is known that some improvement is necessary, and learning is performed from the integrated value integrated in the storage means (STEP 31). Environment can be addressed.
[0067]
For example, at a time when the integrated value of the storage means converges to zero, counting up can be prevented by increasing the predetermined time of 12 minutes. The count-up can be prevented by increasing the amount so as not to count up in a short time. By correcting the predetermined time and the predetermined flow rate while learning in this way, erroneous measurement can be prevented.
[0068]
By displaying whether there is an abnormality when there is no fluctuation or an abnormality when there is fluctuation, it is possible to grasp the abnormal state of the flow path, and after the abnormality is confirmed, take an early action to improve the abnormality. It is possible.
[0069]
When an abnormality is confirmed, the mode returns to the high-accuracy measurement mode for more accurate measurement, so that power consumption increases and the life of the battery 35 may be shortened. That is,
[0070]
Further, the measurement abnormality determination processing (STEP 23) of the measurement abnormality determination means 38 includes a predetermined time (for example, 12 minutes) for determining the count up of the flow rate, an integrated flow value (for example, 1 liter) within the predetermined time, and a measuring method. An abnormality is determined from the number of times of change.
[0071]
For example, the frequency frequently exceeds one liter of the predetermined integrated flow rate before the predetermined time, or the measurement method frequently changes (for example, 100 times or more per day) between the low power consumption mode and the high accuracy measurement mode. When the measurement is performed, since the measurement is obviously not normal, the measurement abnormality determination unit 38 determines that the measurement is abnormal, and displays an abnormality warning on the warning display unit 34.
[0072]
This makes it possible to detect a measurement mode switching abnormality at an early stage, realize stable flow measurement, and improve measurement accuracy.
[0073]
When the measurement processing is arranged, it can be shown in a hierarchical structure as shown in FIG. In addition, although the description has been made with reference to the ultrasonic flow rate measuring means, when a plurality of flow rate measuring methods are used using a flow meter such as a flow sensor, a fluid flow meter, or a mechanical flow meter such as a membrane meter, the mechanical It is easy to guess that it is possible to achieve both low power consumption and high accuracy by using a flow meter as a low power consumption flow measurement unit and a flow sensor as a high precision flow measurement unit.
[0074]
Although the above description has been made on the basis of two classifications of a large flow rate and a small flow rate, the accuracy can be further improved by finely dividing the flow rate into three or more classifications of a large flow rate, a medium flow rate and a small flow rate. Further, although the description has been made assuming that the integrated flow rate is equal to or more than the predetermined flow rate, the same applies to the detection before the predetermined flow rate is reached. And although it demonstrated as fluctuation, it is clear that it is effective for measurement of the pulsating flow generated in a gas pipe.
[0075]
In addition, in the case of gas meters that measure gas flow, security functions for grasping gas leaks and use conditions of gas appliances and managing safety are added, but high-precision flow measurement means are processed according to requests from these security functions. Could be done.
[0076]
When an abnormality is determined, it is easy to provide a gas shut-off means so as to perform not only a warning display but also gas shut-off.
[0077]
In addition, since the battery is used as the driving power source, it is conceivable that the life can be extended by switching to the low power consumption flow rate measuring means according to the battery consumption status. Can be used as a safety meter.
[0078]
(Example 2)
Example 2 will be described with reference to FIG. The difference from the first embodiment is that a transmission / reception repetition unit 39 for repeatedly transmitting and receiving ultrasonic waves and a measurement repetition unit 40 for repeating the measurement of the transmission / reception repetition unit 39 are further provided.
[0079]
That is, the first propagation time measurement T1 when transmission / reception from the upstream side to the downstream side of the flow path 21 is repeated and the second propagation time measurement T2 when transmission / reception from the downstream side to the upstream side are repeated are 1 The transmission / reception repetition means 39 as one measurement unit, the measurement repetition means 40 for repeating the measurement of the transmission / reception repetition means 39 at least once, and the transmission / reception repetition means 39 and the measurement repetition means 40 are repeated. The flow rate detecting means 41 for detecting the flow rate from the total first propagation time ΔT1 and the total second propagation time ΔT2 at the time; And an ultrasonic flow rate measuring means 42 for realizing a high-accuracy flow rate measuring means and a low power consumption flow rate measuring means by changing the number M of measurement repetitions.
[0080]
More specifically, the high-accuracy flow rate measuring means reduces the number N of transmission / reception repetitions by the repetition number changing means 27 (for example, 1 to 16 times, optimally 2 times) and conversely increases the number M of measurement repetitions. (For example, 16 to 1024 times, optimally 126 times), and set so that the total product N * M increases.
[0081]
With such a setting, a change in the pulsating flow velocity, which changes drastically over time, is measured finely, and high precision is realized by measuring the change over a long period of time.
[0082]
Further, the low power consumption flow rate measuring means increases the number N of transmission / reception repetitions (for example, 8 to 512 times, optimally 64 times) by the repetition number changing means 27, and decreases the number M of measurement repetitions (for example, 1 to 1). From eight times, optimally once) to complete the measurement in a short time. The means for performing the measurement switching of the measuring means is the measurement switching means 29.
[0083]
According to the configuration of the present embodiment, as shown in FIG. 8, by measuring with a reduced number of transmission / reception repetitions, the timing of measuring the propagation time from the upstream and the propagation time from the downstream can be close to each other, and the time change can be reduced. The measurement accuracy can be improved even in the case of a violent pulsation.
[0084]
Since the measurement unit for transmission and reception can be repeatedly performed by the measurement repetition means 40 and long-time measurement can be performed, the fluctuating propagation time can be averaged, and the accuracy can be further improved.
[0085]
Although the measurement unit is repeated continuously through the waiting time, the measurement accuracy can be improved by adjusting the waiting time to adjust the total measurement time.
[0086]
Obviously, the shorter the waiting time, the more precise the measurement and the more accurate the measurement. Then, by combining the number of transmission / reception repetitions N and the number of measurement repetitions M, an intermediate measurement mode between the low power consumption mode and the high-accuracy measurement mode can be created.
[0087]
For example, when the pulsation is large and the flow rate range is a small flow rate range, a number of intermediate measurement modes can be realized as measurement modes with slightly higher accuracy and reduced power consumption.
[0088]
Further, by changing the number of repetitions to match the cycle of the pulsation, the influence of the pulsation can be reduced as much as possible, and the flow measurement accuracy can be improved.
[0089]
【The invention's effect】
As is clear from the above description, the flow meter according to the present invention has the following advantages.
[0090]
A high-accuracy flow measurement unit, a low-power consumption flow measurement unit, and a measurement switching unit that switches the flow measurement unit according to the measurement flow of at least one of the high-precision flow measurement unit and the low-power consumption flow measurement unit. With this configuration, a plurality of flow rate measuring means can be switched and used, and both high-accuracy flow rate measurement and low power consumption flow rate measurement can be realized.
[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 diagram illustrating the principle of the flow meter.
FIG. 3 is a diagram illustrating the principle of the flowmeter.
FIG. 4 is a flowchart of the flow meter.
FIG. 5 is a flowchart of the flow meter.
FIG. 6 is a flowchart of the flow meter.
FIG. 7 is a block diagram showing a second embodiment of the present invention.
FIG. 8 is a diagram illustrating the principle of the flow meter.
FIG. 9 is a block diagram of a conventional flow meter.
FIG. 10 is a block diagram of another conventional flow meter.
[Explanation of symbols]
21 Channel
22, 23 sound wave transmitting / receiving means
24 Repeat means
25 Timekeeping means
26 Flow rate detection means
27 Number change means
28 Ultrasonic flow rate measuring means
29 Measurement switching means
30 Fluctuation detection means
31 Flow rate determination means
32 Flow rate integration means
33 Flow rate abnormality determination means
34 Warning display means
35 batteries
36 Flow rate storage means
37 Flow rate display means
38 Measurement abnormality determination means

Claims (16)

High-precision flow measurement means, low power consumption flow measurement means, measurement switching means for switching the flow measurement means by the measurement flow of at least one flow measurement means of the high-precision flow measurement means and the low power consumption flow measurement means, With a flow meter. The high-precision flow rate measuring means is provided in a flow path, a pair of sound wave transmitting and receiving means for transmitting and receiving a sound wave, a repeating means for repeatedly transmitting and receiving the sound wave by the sound wave transmitting and receiving means, and a sound wave while being repeated by the repeating means. A time measuring means for measuring the propagation time, a flow rate detecting means for detecting a flow rate based on the value of the time measuring means, and a repetition number changing means for changing the repetition number of the repetition means, wherein the repetition number changing means The flowmeter according to claim 1, wherein the number of repetitions is increased to perform high-accuracy flow measurement. The low-power-consumption flow rate measuring means is provided in the flow path, and transmits and receives a sound wave. A pair of sound wave transmitting and receiving means, a repeating means for repeatedly transmitting and receiving sound waves by the sound wave transmitting and receiving means, A timer for measuring the propagation time of the sound wave; a flow rate detector for detecting a flow rate based on the value of the timer; and a repetition number changing means for changing the number of repetitions of the repetition means. 2. The flowmeter according to claim 1, wherein the number of repetitions is reduced by the means to measure the low power consumption flow rate. Repetition of transmission and reception using one measurement unit as the first propagation time measurement when transmission and reception from the upstream side to the downstream side are repeatedly performed and the second propagation time measurement when transmission and reception from the downstream side to the upstream side are repeatedly performed. Means, a measurement repeating means for repeating the measurement of the transmission / reception repeating means at least once or more, a total first propagation time and a total second propagation time when the transmission / reception repeating means and the measurement repeating means repeat the measurement. A flow rate detecting means for detecting a flow rate from the apparatus, and an ultra-high-speed flow rate measuring means and a low power consumption flow rate measuring means by changing the number of transmission / reception repetitions of the transmission / reception repetition means and the number of measurement repetitions of the measurement repetition means. The flow meter according to claim 1, further comprising an acoustic flow rate measuring means. A fluctuation detecting means for detecting a flow fluctuation from a measurement value of the low power consumption flow measuring means, and a measurement switching means for switching the flow measuring means so as to measure by the high precision flow measuring means when the fluctuation detecting means detects the fluctuation. The flowmeter according to claim 1, further comprising: The flow rate determining means for determining the flow rate range from the measurement value of the high-precision flow rate measuring means, and when the flow rate determining means determines that the flow rate is small, the flow rate measurement by the high-precision flow rate measuring means is continued, and the flow rate determining means determines the large flow rate. 2. The flow meter according to claim 1, further comprising: a measurement switching unit that switches the flow measurement unit to the low power consumption flow measurement unit when the determination is made. A flow rate integrating means for integrating the instantaneous flow rate value measured by the flow rate measuring means for a predetermined time; and a measurement switching means for switching to a high-precision flow rate measuring means when the integrated value of the flow rate integrating means becomes equal to or more than a predetermined flow rate value. Item 7. The flow meter according to Item 1. 8. The flowmeter according to claim 7, further comprising a flow rate abnormality determining means for determining whether or not the integrated value of the flow rate is normal based on the flow rate value measured by the high precision flow rate measuring means. 8. The flowmeter according to claim 7, further comprising a flow rate integrating means for clearing the integrated flow rate value when the integrated flow rate value does not exceed the predetermined flow rate even after the predetermined time has elapsed. 9. The flowmeter according to claim 8, further comprising a flow integrating means for clearing the integrated flow value when the flow abnormality determining means determines that the flow rate is not normal. 11. A flow rate integrating means for clearing an integrated flow value when the flow rate abnormality determining means determines that it is not normal, and a flow rate storing means for storing an integrated flow value before clearing. Flow meter according to the item. The flow meter according to any one of claims 7 to 11, further comprising flow rate display means for displaying an integrated flow rate, wherein a unit of the least significant digit of the flow rate display means is a predetermined flow rate. The flow meter according to claim 12, wherein the predetermined flow rate is 1 liter. The flow meter according to claim 7, wherein the predetermined time is 1 minute or more, and 12 minutes is optimal. 8. The apparatus according to claim 7, further comprising: a measurement abnormality determination unit configured to determine an abnormality based on the predetermined time, the integrated flow rate value, and the number of times the measurement method has been changed, and a warning display unit configured to display an abnormality warning when the measurement abnormality determination unit determines the abnormality. Flowmeter. The flow meter according to any one of claims 1 to 15, wherein the battery is a power supply.

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